ok, so I cleaned the PCV valve...
alan
rattling noise when shaken. If you blow gently from the intake side,
air will pass through, but if you blow slightly harder, it stops.
I then cleaned it out with throttle body cleaner. Now it rattles more
loudly, and I have to blow harder before the valve closes. Does this
sound about right?
Caroline
you pinch the PCV hose and listen for a click?
Might not be good for all cars. Post your year and model, and I might be able to
tell you.
"alan" <no-long...@yahoo.com> wrote
Tegger®
news:ca059r$iqf$1...@news.Stanford.EDU:
Yes.
--
TeGGeR®
How to find anything on the Internet or in Usenet Groups:
www.google.com
www.groups.google.com
alan
> Did you do the little PCV vavle test where, with the valve properly installed,
> you pinch the PCV hose and listen for a click?
No. It's tucked under the intake manifold, so I can't reach it unless I
start taking off hoses.
>
> Might not be good for all cars. Post your year and model, and I might be able to
> tell you.
97 Integra GSR
JM
No. replacing it for $5 sounds about right.
JM
Caroline
> Caroline wrote:
>
> > Did you do the little PCV valve test where, with the valve properly
installed,
> > you pinch the PCV hose and listen for a click?
>
> No. It's tucked under the intake manifold, so I can't reach it unless I
> start taking off hoses.
>
> > Might not be good for all cars. Post your year and model, and I might be
able to
> > tell you.
>
> 97 Integra GSR
I haven't seen any easy-to-retrieve online manuals for this. (A couple of online
manual resources exist for pre-1996 or so Honda models.)
The following has drawings and a description of this little test for 1995-1997
Civics, for what it's worth.
http://www.honda.co.uk/owner/CivicManual/pdf/11-109.pdf
If you're very concerned, just buy a new valve. They're not very expensive.
If you're not so concerned, and have no symptoms of a malfunctioning PCV valve
(e.g. reduced fuel mileage; oil seals leaking oil), then trust that your cleanup
of the valve went fine and put it back in.
y_p_w
Caroline wrote:
> "alan" <no-long...@yahoo.com> wrote
>
>>Caroline wrote:
>>
>>
>>>Did you do the little PCV valve test where, with the valve properly
>
> installed,
>
>>>you pinch the PCV hose and listen for a click?
>>
>>No. It's tucked under the intake manifold, so I can't reach it unless I
>>start taking off hoses.
>>
>>
>>>Might not be good for all cars. Post your year and model, and I might be
>
> able to
>
>>>tell you.
>>
>>97 Integra GSR
>
>
> I haven't seen any easy-to-retrieve online manuals for this. (A couple of online
> manual resources exist for pre-1996 or so Honda models.)
>
> The following has drawings and a description of this little test for 1995-1997
> Civics, for what it's worth.
>
> http://www.honda.co.uk/owner/CivicManual/pdf/11-109.pdf
From my "Integra Service Manual 1995":
"2. At idle, make sure there is a clicking sound from the PCV valve,
when the hose between PCV valve and intake manifold in [sic] lightly
pinched with your fingers or pliers."
I'll just say that the PCV valve of my '95 GS-R is a PITA to reach
without taking out stuff. I can't even fit a pair of pliers in
there to do the test. My '89 Integra had an easy to reach PCV valve
location. BTW - anyone knows what needs to be taken out?
> If you're very concerned, just buy a new valve. They're not very expensive.
OEM at the dealer is going to be way more. However - it's not something
that's replaced all that ofter.
> If you're not so concerned, and have no symptoms of a malfunctioning PCV valve
> (e.g. reduced fuel mileage; oil seals leaking oil), then trust that your cleanup
> of the valve went fine and put it back in.
I might be desperate enough to take it to a mechanic to do. PCV valves
are easy to replace in most cars, but the location in a GS-R is just
ridiculous.
alan
I unplugged the hose that connects the valve cover to the intake before
the throttle body, and the coolant line that runs to the throttle body.
Then, you can barely fit your hand in there to pull the PCV valve out
from the engine. Then you can barely fit some pliers in there to remove
the hose clamp that holds the PCV valve on.
>
>> If you're very concerned, just buy a new valve. They're not very
>> expensive.
>
>
> OEM at the dealer is going to be way more. However - it's not something
> that's replaced all that ofter.
yeah, it's like $20 around here
Tegger®
news:1aSwc.4712$uX2...@newsread2.news.pas.earthlink.net:
> If you're not so concerned, and have no symptoms of a malfunctioning
> PCV valve (e.g. reduced fuel mileage; oil seals leaking oil),
Those are not symptoms of a plugged PCV valve. Stop misleading people.
--
TeGGeR®
The Unofficial Honda FAQ
http://www3.telus.net/public/johnings/faq.html
Caroline
Caroline wrote
> > If you're very concerned, just buy a new valve. They're not very expensive.
>
> OEM at the dealer is going to be way more.
Sure. But $20 still isn't a lot every 60k miles or so.
> However - it's not something that's replaced all that ofter.
Autozone online sells two makes of PCV valve for the 97 Integra:
Deutsch: $3
Beck-Arnley: $11.56
Add $3 or so to replace the grommet.
Online parts sites say their prices are discounted from a retail cost of about
$20.
Caroline
> "Caroline" <caroline1...@earthlink.net> spake
> > If you're not so concerned, and have no symptoms of a malfunctioning
> > PCV valve (e.g. reduced fuel mileage; oil seals leaking oil),
>
> Those are not symptoms of a plugged PCV valve. Stop misleading people.
The latest (of many) citations on this:
Autozone: *** REPLACING YOUR "PCV VALVE" CAN IMPROVE YOUR ENGINE IDLE AND FUEL
ECONOMY.*** http://tinyurl.com/yqbra
"P.C.V. malfunctions lower fuel economy since it is a vacuum device."
http://www.leeric.lsu.edu/bgbb/7/ecep/auto/n/n.htm
Citations from our past discussion:
http://www.inct.net/~autotips/mpg.htm
http://www.autoshop101.com/forms/h63.pdf
http://www.thecarconnection.com/index.asp?n=158,277&sid=277&article=4681
http://www.interro.com/techgas.html
http://www.womanmotorist.com/index.php/news/main/2522/event=view
http://www.is-it-a-lemon.com/fuel/pcv_valve.htm
http://www.courier-tribune.com/guide/gasmileage.html
Googling will turn up more. Try {"PCV valve" "fuel economy"}
On plugged PCV valves causing oil leaks:
"A restricted PCV valve can cause this excess pressure to find new avenues to
vent, and an oil gasket or seal is usually "blown out" to let this pressure
escape." http://www.trustmymechanic.com/valve_cover_leak.htm
"Engine is using more oil than normal. Oil puddles under the car when parked...
The PCV system is not working properly: Replace PCV valve."
http://autorepair.about.com/cs/troubleshooting/a/bl303a_3.htm
These are merely the very first two hits of a Google search for {"PCV Valve"
"oil leak"}.
The my personal experience: Replacing my 91 Civic's PCV valve late last winter
increased fuel economy over 10%. I was getting below 40 mpg, probably around 35
mpg. Spring-Fall, 2003, I got over 40 mpg consistently. This dipped under 40 mpg
during the winter, but then around March I checked my PCV valve and it was again
somewhat fouled.
Last three tanks of gas: 42, 43, and 41 mpg.
The reader can make his/her own decision on this.
Tegger®
> "Tegger®" <teggerati...@changetheobvious.invalid> wrote
>> "Caroline" <caroline1...@earthlink.net> spake
>> > If you're not so concerned, and have no symptoms of a
>> > malfunctioning PCV valve (e.g. reduced fuel mileage; oil seals
>> > leaking oil),
>>
>> Those are not symptoms of a plugged PCV valve. Stop misleading
>> people.
>
> The latest (of many) citations on this:
<snip>
> Googling will turn up more. Try {"PCV valve" "fuel economy"}
So if the same nonsense gets repeated often enough, it becomes true?
This is what is known as "Internet wisdom". Do a Google for some famous
quotes that come to mind and see how many pages attribute the quote to the
wrong person, or get the quote wrong entirely.
This PCV thing is one of those nonsense "facts".
A plugged PCV valve does not affect gas mileage. End of story.
>
> On plugged PCV valves causing oil leaks:
> "A restricted PCV valve can cause this excess pressure to find new
> avenues to vent, and an oil gasket or seal is usually "blown out" to
> let this pressure escape."
> http://www.trustmymechanic.com/valve_cover_leak.htm
It is necessary that BOTH the crankcase breather AND the PCV valve get
plugged.
And even then it would pump itself out the path of least resistance first,
usually the oil dipstick tube or something like a failing oil pan gasket.
>
> The my personal experience: Replacing my 91 Civic's PCV valve late
> last winter increased fuel economy over 10%. I was getting below 40
> mpg, probably around 35 mpg. Spring-Fall, 2003, I got over 40 mpg
> consistently. This dipped under 40 mpg during the winter, but then
> around March I checked my PCV valve and it was again somewhat fouled.
>
> Last three tanks of gas: 42, 43, and 41 mpg.
I am convinced your numbers are in error. You have stated previously that
you never drive more than 5 or 10 minutes at a time, in suburban driving.
Your car is running COLD, and slowly, for most its running time. By the
time it goes to closed-loop, you have shut it off.
The EPA, normally quite optimistc when it comes to gas mileage figures,
lists 37mpg for your car at highway speed, much less than that for city
driving.
Sorry, but your claim of 40mpg is just not at all credible.
Tegger®
> "y_p_w" <y_...@hotmail.com> wrote
> Caroline wrote
>> > If you're very concerned, just buy a new valve. They're not very
>> > expensive.
>>
>> OEM at the dealer is going to be way more.
>
> Sure. But $20 still isn't a lot every 60k miles or so.
And if you take care of your car and change the oil properly, the valve
will last the life of the car without cleaning.
y_p_w
Well - I may just end up doing that. It sounds like you're talking about
the breather tube and the coolant line running to the idle control valve.
It shouldn't leak too much coolant, especially since it's higher than
the top of the radiator.
I also need to clean off the area around the PCV valve. It's collected
a lot of grime in 132K miles. It's also losing a lot more oil than it
used to, and I'm thinking it might have something to do with the
original PCV valve.
> >> If you're very concerned, just buy a new valve. They're not very
> >> expensive.
> >
> >
> > OEM at the dealer is going to be way more. However - it's not something
> > that's replaced all that ofter.
>
> yeah, it's like $20 around here
I remember something like $13 a few years back for a PCV valve for my
'89 Integra. I didn't really need a new one, since the old one passed
the pinch and click test, as well as the shake the thing around test.
Caroline
snip non-rebuttal
> It is necessary that BOTH the crankcase breather AND the PCV valve get
> plugged.
We've been over this. If the PCV valve plugs, that's one less path for the
crankcase gases to escape. Steady state crankcase pressure thus will be higher
with a plugged PCV valve. This places more pressure on various oil seals. Thus
they may fail sooner.
> And even then it would pump itself out the path of least resistance first,
> usually the oil dipstick tube or something like a failing oil pan gasket.
An oil pan gasket is one of the seals that can fail, correct.
snip
Caroline wrote:
> > Last three tanks of gas: 42, 43, and 41 mpg.
>
> I am convinced your numbers are in error. You have stated previously that
> you never drive more than 5 or 10 minutes at a time, in suburban driving.
No, Tegger. You should have googled. I wrote on May 3:
"I for one do very little highway driving apart from vacations. My trips have
always tended more towards 10-20 minute runs to work or the grocery, etc."
Right now I typically drive 20 minutes to the grocery or hardware store, each
way.
> Your car is running COLD, and slowly, for most its running time. By the
> time it goes to closed-loop, you have shut it off.
I live in a climate that is pretty warm 3/4 of the year. The car is warmed up in
five minutes during these nine, warm weather months.
> The EPA, normally quite optimistc when it comes to gas mileage figures,
I don't know that the EPA is normally optimistic or not. I have seen other
non-Honda reports of people getting mileage better than the government site.
> lists 37mpg for your car at highway speed, much less than that for city
> driving.
Wrong again, Tegger. The site says my car is supposed to get 35 mpg at highway
speeds.
> Sorry, but your claim of 40mpg is just not at all credible.
For the rational among us, further proof that 40 mpg or more on a circa 1991
Civic is not unusual:
Sean Dinh, 1998/09/05:
"Same maintenance schedule as 91 Civic. It's handling doesn't even come close to
the 91 Civic sedan. Get 40+ mpg on highway. 50+ if I drive at legal
speed(Warning: Dangerous to your health). 40's
around town."
Stew King, 1997/03/19:
"... my '92 Civic 4dr 5sp regular gets better than 40 mpg (17km/l?) highway. I
don't do very much city driving so i can't help you there."
(dcornel...@cinternet.net), 1998/01/09:
"91 civic HB DX 5-speed (No AC)
Best: 44 mpg HWY (5-10mph over legal typically)
Ave: 39 mpg hwy 35 city"
Priyantha Mathupala, 2001-02-15:
"I got my 91' Civic timing belt and water pump replaced @ 100,000 miles. The car
was doing 40 mpg and running very smoothly up to that point."
Mathu, 2004-05-21:
"I know exactly what you mean by this "ticking" sound. I have a
91 Civic, and I have been living with this ticking/clicking sound for
almost 5 years. But the car runs fine, gives about 40-41 mpg."
Natural Born Cynic, 1999/09/12:
"I had a Honda Civic Dx that would regularly get 40-44 mpg on long trips, this
was with a lead foot. However, one time on a long trip I stayed at 55 mph, and
slowed down up
hills by not increasing pressure on the gas pedal, and got 55 miles /gallon."
Richard J. Dudley, 1996/05/09:
"I get approx. 40 mpg with 87 octane Chevron in my 91 Civic DC 5-speed on the
highway, and about 33-35 in the city."
Scott Ramoly, 2000-09-15:
"I don't know the differences between your 89 Civic and my 88 Civic DX (manual);
but with 225,000 miles I am still getting about 35 MPG. Used to get as high as
42 MPG on the road."
Timothy Lee, 1998/01/20:
"But old Civic wagons got up to 40 mpg (though the 4wd version was probably
somewhat lower)."
Zero, 2000/04/29:
"I had a 91' DX 5-speed. I got 30-35 driving hard (the car was slow as hell so
I made up for it by accelerating AFAP all the time). I'd get 35-40 on the
highway. My mom had a 89 civic waqon 5-speed (same drivtrain) and she got 40-45
when it was new. It has 300,000 on it and still gets over 35."
All quotations above are in the Usenet archive. Specifically, see
http://tinyurl.com/25dqt , the results of an advanced www.groups.google.com
search using
{ 91 Civic (40 OR 41 OR 42 OR 43 OR 44) mpg group:alt.autos.honda, OR
group:rec.autos.makers.honda }.
Many others on Usenet have attested to 40+ mpg on their 91 Civics, but I have
omitted those who are trying to sell their car.
Jafir Elkurd
(86-89 accord.) The valve has even been superseded now because it was such
a problem.
"Tegger®" <teggerati...@changetheobvious.invalid> wrote in message
news:Xns95018CDB2A6...@207.14.113.17...
Tegger®
in news:10c9ppa...@corp.supernews.com:
> Until the inside breaks out,
What? The spring and plunger BREAKING? Proof please. And not Google results
either.
y_p_w
> "Caroline" <caroline1...@earthlink.net> spake unto the masses in
> news:7y%wc.24848$Tn6....@newsread1.news.pas.earthlink.net:
>
> > "Tegger®" <teggerati...@changetheobvious.invalid> wrote
> >> "Caroline" <caroline1...@earthlink.net> spake
> >> > If you're not so concerned, and have no symptoms of a
> >> > malfunctioning PCV valve (e.g. reduced fuel mileage; oil seals
> >> > leaking oil),
> >>
> >> Those are not symptoms of a plugged PCV valve. Stop misleading
> >> people.
> >
> > The latest (of many) citations on this:
>
>
> <snip>
>
>
> > Googling will turn up more. Try {"PCV valve" "fuel economy"}
>
>
>
> So if the same nonsense gets repeated often enough, it becomes true?
>
> This is what is known as "Internet wisdom". Do a Google for some famous
> quotes that come to mind and see how many pages attribute the quote to the
> wrong person, or get the quote wrong entirely.
>
> This PCV thing is one of those nonsense "facts".
>
> A plugged PCV valve does not affect gas mileage. End of story.
Dude - I read it and saw who the source was:
"A malfunctioning P.C.V. may result in a hard starting engine, surge
at cruise, and hesitation on acceleration. P.C.V. malfunctions lower
fuel economy since it is a vacuum device."
and the source (at least the guy who cross-checked the info).....
CURRICULUM WRITER & PROGRAM CONSULTANT
Joseph H. Pons, III.
Associate Professor
Industrial Technology
University of Southwestern Louisiana
He seems to have either retired or moved on from Southeastern Louisiana
University. I did find his CV in a cached archive:
"Joe Pons has 23 years university teaching. Prior to joining the
ITEC faculty, he worked for Ford Motor Co. as a zone technical
manager and district parts and service management consultant. He
has also taught two years at a secondary school and one year at a
post-secondary technical institute. Technical interests lie in
mechanical and fluid power technologies, and he serves as the
coordinator for these courses. Upper level courses include these
aspects of automation and robotics.
He earned a BS degree in Industrial Arts Education from louisiana
and a MS from LSU in Adult Vocational and Technical Education with
a minor in Management. While at Ford, prior to receiving his MS, he
acquired extensive management training."
Jafir Elkurd
to prove it to me. A bad PCV valve causing rough running and high oil
consumption was quite common on 86-89 accords. Not so common anymore
because many of them have had the PCV valve replaced.
"Tegger®" <teggerati...@changetheobvious.invalid> wrote in message
news:Xns9501C68329F...@207.14.113.17...
Jafir Elkurd
"Jafir Elkurd" <ja...@nospam.no.spam.hotpop.com> wrote in message
news:10cabv6...@corp.supernews.com...
George Macdonald
<teggerati...@changetheobvious.invalid> wrote:
>"Caroline" <caroline1...@earthlink.net> spake unto the masses in
>news:1aSwc.4712$uX2...@newsread2.news.pas.earthlink.net:
>
>> If you're not so concerned, and have no symptoms of a malfunctioning
>> PCV valve (e.g. reduced fuel mileage; oil seals leaking oil),
>
>
>
>Those are not symptoms of a plugged PCV valve. Stop misleading people.
We've been through all this before - I guess it just got left dangling.:-)
I know (think ?) we agreed that the PCV is a metered air leak. How can it
not affect engine efficiency and therefore fuel mileage? BTW I'm quite
sure that a PCV can fail in more ways than getting plugged up - e.g. the
spring can get gunked up and bind. The PCV lives an environment which is
not kind to metal or even plastics.
I'm quite sure that the reason the rubber plug at the end of the exhaust
camshaft of an Integra, next to the distributor, gets pushed out is because
of crankcase pressure increase. It seems to happen more in Winter when the
PCV can get frozen up.
Rgds, George Macdonald
"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??
SoCalMike
> I'm quite sure that the reason the rubber plug at the end of the exhaust
> camshaft of an Integra, next to the distributor, gets pushed out is because
> of crankcase pressure increase. It seems to happen more in Winter when the
> PCV can get frozen up.
if you wanna be safe and not necessarily "ecologically correct", im sure
you could get a second oil cap and put some kind of foam filter or valve
tapped into it for good measure :)
swap it back for the biennual smog check tho!
Tegger®
masses in news:oufac0t3919lbv113...@4ax.com:
>
> I know (think ?) we agreed that the PCV is a metered air leak. How
> can it not affect engine efficiency and therefore fuel mileage?
Because the air and blowby is coming from, and going to, the SAME PLACE AT
ALL TIMES.
Go take a good hard look at your own PCV system. See where the crankcase
takes in air. See where the PCV valve dumps its air. Notice that BOTH are
located in the INTAKE tract, mere inches from each other?
There is NO "air leak".
The valve does NOT introduce new air into the system.
It simply meters the existing air so as to ensure that there is POSITIVE
flow through the crankcase, resulting in a constant changeover of the air
in the crankcase, with any blowby gases routed back through the combustion
chamber again.
A blocked PCV Valve but a free breather will cause the gases to cavitate
inside the crankcase. Since the breather will be under slight depression
from the intake tract, pressure will be higher in the crankcase than the
intake, so excess gases will get pushed into the intake and recycled
through the combustion chamber again, just as if they went through the PCV
properly, but there will be be no positive flow.
The main purpose of the PCV valve is to ensure that one end of the breather
system always has a lower pressure than the other, so that one end will
always be an intake, and one will always be an outlet. That is why it has a
variable orifice.
> BTW
> I'm quite sure that a PCV can fail in more ways than getting plugged
> up - e.g. the spring can get gunked up and bind.
How is this different from being "plugged up"?
The PCV plunger is surrounded by the spring. The metered orifice is the
SPACE around the coils of the spring. If the spring gets gunked up, then
the orifice is reduced, becuase the orifice IS around the spring.
> The PCV lives an
> environment which is not kind to metal or even plastics.
And it is made of metal and oil-compatible plastics. You don't think they
would think of doing that?
>
> I'm quite sure that the reason the rubber plug at the end of the
> exhaust camshaft of an Integra, next to the distributor, gets pushed
> out is because of crankcase pressure increase. It seems to happen
> more in Winter when the PCV can get frozen up.
It happens because the rubber gets old and has reduced holding power,
especially when cold. It is only really clamped in place by the two little
ridges on it anyway. This explained to me by my Japanese mechanic. I
replaced my leaky old one a few years ago. It has not leaked since.
In order for pressure to build to the point where it could possibly "push
the plug out", BOTH the PCV AND the breather MUST be blocked.
Tegger®
news:591da479.04060...@posting.google.com:
> "Tegger®" <teggerati...@changetheobvious.invalid> wrote in
>>
>> A plugged PCV valve does not affect gas mileage. End of story.
>
> Dude - I read it and saw who the source was:
>
> "A malfunctioning P.C.V. may result in a hard starting engine, surge
> at cruise, and hesitation on acceleration. P.C.V. malfunctions lower
> fuel economy since it is a vacuum device."
The PCV *SYSTEM*, or the PCV *VALVE*?
Your quote does not say.
If the PCV *system* is malfunctioning, then definitely those symptoms may
be caused. Such as if the breather hose is cracked or disconnected. Such as
if the PCV valve grommet has perished and is letting air in around the
valve stem.
I am starting to suspect that posters here are thinking that the "system"
consists of the valve alone.
Tegger®
> Tegger wrote:
> snip non-rebuttal
>> It is necessary that BOTH the crankcase breather AND the PCV valve
>> get plugged.
>
> We've been over this. If the PCV valve plugs, that's one less path for
> the crankcase gases to escape. Steady state crankcase pressure thus
> will be higher with a plugged PCV valve. This places more pressure on
> various oil seals. Thus they may fail sooner.
Wrong. Totally incorrect understanding of the PCV system.
And even if plugged, a PCV valve will NOT affect mileage.
Tegger®
masses in news:oufac0t3919lbv113...@4ax.com:
> I know (think ?) we agreed that the PCV is a metered air leak. How
> can it not affect engine efficiency and therefore fuel mileage?
I just asked my mechanic, who has specialized in Japanese cars for 40 years
and has run his own shop for the last twenty (no, from 1980, so 24 years).
He does everything up to and including rebuilding engines and
troubleshooting electronics problems.
He says a plugged PCV valve will definitely NOT affect gas mileage. End of
story. The computer would compensate for any metering incorrectness
resulting therefrom.
That makes three *actual working mechanics*, all with many years of
experience, who have told me that a plugged PCV valve WILL NOT affect gas
mileage.
Caroline's many instances of Google results are WRONG. Plain and simple
WRONG. "Internet legends" is what they are. WRONG. Misleading.
w_tom
bothered with PCV valves because minor dirt in PCV valves
would cause major problems with air mixture in carburetion.
In fact I am surprised Honda has even gone to PCV valves.
1980s Hondas never used PCV valves. Hondas has a superior
alternative design. But then with fuel injection, changes in
air bypass do not adversely affect air mixture. Throttle is
just another source of air leakage in a fuel injected system.
IOW that text is probably correct when PCV valves were
connected to carburetors. It does not apply to fuel injected
system.
Alan - don't worry about the PCV valve. The valve does
exactly as you have described. If a valve is so clogged as to
cause crankcase ventilation problems, then the engine has far
more serious problems than a clogged PCV valve.
Matthew Hunt
George Macdonald <fammacd=!SPAM^noth...@tellurian.com> wrote:
> I know (think ?) we agreed that the PCV is a metered air leak. How can it
> not affect engine efficiency and therefore fuel mileage? BTW I'm quite
> sure that a PCV can fail in more ways than getting plugged up - e.g. the
> spring can get gunked up and bind.
Yes, mine failed "open" (94 del Sol Si). When I pinched the hose
at idle, there was no click and the idle changed. If it had been
plugged, there would also have been no click, but the idle would not
have changed.
George Macdonald
> What year was this written? Years ago, Honda never even
>bothered with PCV valves because minor dirt in PCV valves
>would cause major problems with air mixture in carburetion.
>In fact I am surprised Honda has even gone to PCV valves.
>1980s Hondas never used PCV valves. Hondas has a superior
>alternative design. But then with fuel injection, changes in
>air bypass do not adversely affect air mixture. Throttle is
>just another source of air leakage in a fuel injected system.
>
> IOW that text is probably correct when PCV valves were
>connected to carburetors. It does not apply to fuel injected
>system.
Of course it does. A fuel injection system has to know the mass of air
being sucked into the combustion chambers to meter the fuel accurately.
Compensation has to be built into the ECU rules for the metered air leak of
a PCV valve.
> Alan - don't worry about the PCV valve. The valve does
>exactly as you have described. If a valve is so clogged as to
>cause crankcase ventilation problems, then the engine has far
>more serious problems than a clogged PCV valve.
There are lots of ways things can go wrong and several variables. Have
ever taken a PCV valve off and looked down the tube coming from the
breather box? Try it in Winter and you'll see a coating or clog of
emulsified oil down there depending on whether the valve is functioning
properly.
Rgds, George Macdonald
George Macdonald
<teggerati...@changetheobvious.invalid> wrote:
>George Macdonald <fammacd=!SPAM^noth...@tellurian.com> spake unto the
>masses in news:oufac0t3919lbv113...@4ax.com:
>
>> I know (think ?) we agreed that the PCV is a metered air leak. How
>> can it not affect engine efficiency and therefore fuel mileage?
>
>
>
>I just asked my mechanic, who has specialized in Japanese cars for 40 years
>and has run his own shop for the last twenty (no, from 1980, so 24 years).
>He does everything up to and including rebuilding engines and
>troubleshooting electronics problems.
Look I don't really care what your mechanic says. I've been told enough
guff by mechanics over the years to fill an encyclopaedia.
>He says a plugged PCV valve will definitely NOT affect gas mileage. End of
>story. The computer would compensate for any metering incorrectness
>resulting therefrom.
The computer hasn't measured the mass of leaked air - it doesn't know about
it other than some fixed compensation curve built into the engine parameter
profile... based on a properly functioning PCV valve.
>That makes three *actual working mechanics*, all with many years of
>experience, who have told me that a plugged PCV valve WILL NOT affect gas
>mileage.
>
>
>Caroline's many instances of Google results are WRONG. Plain and simple
>WRONG. "Internet legends" is what they are. WRONG. Misleading.
So your mechanics are right and the auto mfrs and engine designers are all
wrong.<shrug>
Caroline
> "Caroline" <caroline1...@earthlink.net> spake
> > snip non-rebuttal
> >> It is necessary that BOTH the crankcase breather AND the PCV valve
> >> get plugged.
> >
> > We've been over this. If the PCV valve plugs, that's one less path for
> > the crankcase gases to escape. Steady state crankcase pressure thus
> > will be higher with a plugged PCV valve. This places more pressure on
> > various oil seals. Thus they may fail sooner.
>
> Wrong. Totally incorrect understanding of the PCV system.
Nope; dead-on correct.
For the rational among us trying to learn about pressure: Think of the crankcase
as a bucket of water being fed with a hose but also having two holes in the
bottom of it. The rate of water flow and the hole sizes are such that 4 inches
of water are maintained in the bucket with this setup. If one suddenly plugs one
of the holes, what happens to the water level in the bucket?
It goes up. Just like the pressure in the crankcase will be higher, on average,
with a plugged PCV valve.
> And even if plugged, a PCV valve will NOT affect mileage.
Forgot to add that various Chilton's manuals also comment on how a
malfunctioning PCV valve may affect mileage. E.g. from the Ford Taurus/Mercury
Sable 1986-1992 Chilton Manual:
"Do not remove the PCV valve system from the engine, as doing so will adversely
affect fuel economy and engine ventilation with resultant shortening of engine
life." -- Emissions Controls, Page 4-6
Re your internet myth "theory":
Guess folks should ignore all the "internet wisdom" that says change your car's
oil every so often, too.
Tegger®
> Look I don't really care what your mechanic says. I've been told enough
> guff by mechanics over the years to fill an encyclopaedia.
So you throw the baby out with the bathwater. They're ALL bad, right?
>
> The computer hasn't measured the mass of leaked air
It's NOT "leaked air". It's the very same air that has already passed by
the throttle plate and the air flow meter.
All the PCV valve does is make sure that flow is always present, and always
in one direction.
This is the part nobody in this group seems to understand. Of course,
nobody in this group is a working mechanic, either (me included). And some
of them aren't even willing to listen to what working mechanics have to
say.
>
> So your mechanics are right and the auto mfrs and engine designers are
> all wrong.<shrug>
Show me ANYWHERE where ANY auto mfr and engine designer says HOW MUCH the
engine will "run rich" with a plugged PCV valve.
I think you guys are all misunderstanding what those auto mfrs and engine
designers are saying. Web pages don't count here.
Tegger®
> "Tegger®" <teggerati...@changetheobvious.invalid> wrote
>
> For the rational among us trying to learn about pressure: Think of the
> crankcase as a bucket of water being fed with a hose but also having
> two holes in the bottom of it. The rate of water flow and the hole
> sizes are such that 4 inches of water are maintained in the bucket
> with this setup. If one suddenly plugs one of the holes, what happens
> to the water level in the bucket?
Bad analogy. Water is not air. Water cannot change density. That's why
hydraulics work the way they do.
You're wrong, Caroline. So completely wrong you have no idea how wrong you
are. Even George is clueless here.
>
> Forgot to add that various Chilton's manuals also comment on how a
> malfunctioning PCV valve may affect mileage. E.g. from the Ford
> Taurus/Mercury Sable 1986-1992 Chilton Manual:
>
> "Do not remove the PCV valve system from the engine,
You should learn to read. It says not to remove the SYSTEM, which is
definitely bad for the motor. The valve is only one part of that system.
Tegger®
> For the rational among us trying to learn about pressure: Think of the
> crankcase as a bucket of water being fed with a hose but also having
> two holes in the bottom of it. The rate of water flow and the hole
> sizes are such that 4 inches of water are maintained in the bucket
> with this setup. If one suddenly plugs one of the holes, what happens
> to the water level in the bucket?
A much more accurate analogy:
Imagine a bucket with ONE hole in the bottom (NEVER plugged). Now make two
holes in the SIDE, one above the other, but both always submerged. Connect
a hose between the two side holes.
THAT's your PCV system, minus the valve itself.
alan
> "Caroline" <caroline1...@earthlink.net> spake unto the masses in
> news:mSNxc.8304$uX2....@newsread2.news.pas.earthlink.net:
>
>
>>"Tegger" <teggerati...@changetheobvious.invalid> wrote
>
>
>>For the rational among us trying to learn about pressure: Think of the
>>crankcase as a bucket of water being fed with a hose but also having
>>two holes in the bottom of it. The rate of water flow and the hole
>>sizes are such that 4 inches of water are maintained in the bucket
>>with this setup. If one suddenly plugs one of the holes, what happens
>>to the water level in the bucket?
>
>
>
>
> Bad analogy. Water is not air. Water cannot change density. That's why
> hydraulics work the way they do.
>
> You're wrong, Caroline. So completely wrong you have no idea how wrong you
> are. Even George is clueless here.
Maybe you guys should crosspost your discussion to rec.autos.tech and
see what some of the guys there say.
Steve G
submerged or below any oil line. The PCV valve is simply a device that
meters the amount of air(crankcase vapour) the intake is allowed to suck
out of the crankcase, all well away from any pool of oil, and the other
hose is a supply of fresh filtered air being drawn into the crankcase ,
again above the oil, to replace the air that the PCV has drawn out.
"TeggerŽ" <teggerati...@changetheobvious.invalid> wrote in message
news:Xns9503EB8F64E...@207.14.113.17...
> "Caroline" <caroline1...@earthlink.net> spake unto the masses in
> news:mSNxc.8304$uX2....@newsread2.news.pas.earthlink.net:
>
>
> > For the rational among us trying to learn about pressure: Think of the
> > crankcase as a bucket of water being fed with a hose but also having
> > two holes in the bottom of it. The rate of water flow and the hole
> > sizes are such that 4 inches of water are maintained in the bucket
> > with this setup. If one suddenly plugs one of the holes, what happens
> > to the water level in the bucket?
>
>
>
> A much more accurate analogy:
>
> Imagine a bucket with ONE hole in the bottom (NEVER plugged). Now make two
> holes in the SIDE, one above the other, but both always submerged. Connect
> a hose between the two side holes.
>
> THAT's your PCV system, minus the valve itself.
>
>
> --
> TeGGeRŽ
Caroline
> "Caroline" <caroline1...@earthlink.net> spake
> > crankcase as a bucket of water being fed with a hose but also having
> > two holes in the bottom of it. The rate of water flow and the hole
> > sizes are such that 4 inches of water are maintained in the bucket
> > with this setup. If one suddenly plugs one of the holes, what happens
> > to the water level in the bucket?
>
> Bad analogy. Water is not air. Water cannot change density.
The analogy has nothing to do with density. It has everything to do with mass
accumulation in a dynamic, fluid system.
BTW, water can change density. Indeed, in liquid pump calculations, the change
in density when moving a liquid such as water may have to be considered during
design.
non-rebuttal snipped
I have no problem with your unfounded opinion. But every time you spout here
that a malfunctioning PCV valve will never affect fuel economy, plan on facing a
rational explanation of why it may, along with a dozen or more citations of
greater repute than you, backing it up.
I too do not think much of putting out misinformation on Usenet.
Caroline
> "Caroline" <caroline1...@earthlink.net> spake
> > crankcase as a bucket of water being fed with a hose but also having
> > two holes in the bottom of it. The rate of water flow and the hole
> > sizes are such that 4 inches of water are maintained in the bucket
> > with this setup. If one suddenly plugs one of the holes, what happens
> > to the water level in the bucket?
> A much more accurate analogy:
Nope.
> Imagine a bucket with ONE hole in the bottom (NEVER plugged).
= the breather hose (which is far far less likely to become plugged than the PCV
valve)
> Now make two
> holes in the SIDE, one above the other, but both always submerged. Connect
> a hose between the two side holes.
>
> THAT's your PCV system, minus the valve itself.
Presumably the level of water denotes the pressure of the gases in the
crankcase. (It does with my analogy.) Presumably in your version, the PCV valve
line is the hose connecting the two side holes.
Then you've got a PCV valve line whose intake is from the crankcase and whose
discharge is to the crankcase.
This is not the case for an actual PCV valve system. The PCV valve intake is
from the crankcase. Its discharge is to the air intake, very close to the
cylinders.
Your pressure relationships do not mimic those in an actual PCV system.
(PCV valve system here = the PCV valve and the hose from the breather chamber to
the PCV valve. This is the way many or all Hondas' PCV systems are set up. Other
cars' PCV hoses come off the valve cover.)
If you're going to consider this carefully, watch your mass flows, their phase
(liquid or gas), and when a chemical reaction (combustion) takes place to affect
pressure. Also, the fact that mass (air and fuel) enters the cylinders via the
intake valves but exits the cylinders via the exhaust valves *and* via blowby
past the pistons.
And since you loathe "Internet wisdom," here's Tom and Ray Magliozzi (yes, the
Car Talk guys), backing up what I have said:
-----
RAY: Blow-by occurs when combustion gasses slip by old, worn-out piston rings
and end up in the crankcase, where they don't belong. Actually, a small amount
of blow-by is normal and is easily expunged by the crankcase ventilation system.
But on old heaps (i.e., yours), worn-out rings can let so much stuff into the
crankcase that the ventilation system just can't handle it.
TOM: So the pressure in the crankcase builds up until gasses and oil try to
escape any way they can. And we often see air-filter housings full of oil, seals
blown out or leaking, and the occasional dribbling dipstick.
RAY: The solution is an engine rebuild, which would include a ring job. But
before you consider that route, or ditch the truck, I've got two other things
for you to try.
TOM: If you've lived a really good, clean life, your problem might just be a
plugged crankcase ventilation system. So have your mechanic check out your PCV
valve and the hose it's attached to. ...
-----
http://lang.motorway.com/home/articles/qandaoilydip.asp
Go ahead and knock two MIT graduates, both of whom worked in their own car
repair shop, and one of whom (Ray) has worked as an auto technician for some 30
years (and is still employed full time as such).
Tegger®
>
> Nope.
--
Tegger®
Note to Caroline: This time, please do not remove the cross-posting. I want
as many minds involved in this debate as possible.
> "Tegger®" <teggerati...@changetheobvious.invalid> wrote
>> "Caroline" <caroline1...@earthlink.net> spake
>> > For the rational among us trying to learn about pressure: Think of
>> > the crankcase as a bucket of water being fed with a hose but also
>> > having two holes in the bottom of it. The rate of water flow and
>> > the hole sizes are such that 4 inches of water are maintained in
>> > the bucket with this setup. If one suddenly plugs one of the holes,
>> > what happens to the water level in the bucket?
>
>
>> A much more accurate analogy:
>> Imagine a bucket with ONE hole in the bottom (NEVER plugged).
>
> = the breather hose (which is far far less likely to become plugged
> than the PCV valve)
You've got it backwards.
If our analogy is to be the bucket with a hole in the bottom, then the top
of the bucket is the throttle inlet and the bottom of the bucket is the
intake valve.
The PCV system has nothing to do with either the throttle or the intake
valve. It simply redirects some of the clean intake gas to the crankcase,
where it picks up blowby, and then directs it back to the intake again.
My anology (countering your erroneous one) has two holes in the side of the
bucket, both in the water, but one above the other with a hose connecting
the two. Absent the blowby, that IS a PCV system. It's just a redirector.
The PCV system does not go to a second intake valve, which is what you
conceptually imply with YOUR analogy of a bucket with two holes in the
bottom.
<snip>
>
> Your pressure relationships do not mimic those in an actual PCV
> system.
Neither do yours. Your bucket analogy consists of a non-compressible fluid
(water) being PUSHED into a container (bucket). The actual intake system of
a car uses a compressible fluid which is SUCKED into the engine.
The intake tract pressure is ALWAYS less than ambient with the engine
running. Hence, in a normal engine, there is ordinarily SUCTION at BOTH
ends of the PCV system. It is necessary to use a restrictor valve to lower
pressure at one end to make sure the flow is always in one direction.
That's the PCV valve.
Are you familiar with the venturi principle? That's all the PCV valve does.
>
> (PCV valve system here = the PCV valve and the hose from the breather
> chamber to the PCV valve. This is the way many or all Hondas' PCV
> systems are set up. Other cars' PCV hoses come off the valve cover.)
It doesn't matter. The principle is identical, even on carbureted cars:
Hose from intake to from crankcase -> Hose from crankcase to PCV valve ->
PCV valve back to intake tract again.
<snip>
>
> And since you loathe "Internet wisdom," here's Tom and Ray Magliozzi
> (yes, the Car Talk guys), backing up what I have said:
<snip quotes from TV personalities saying that heavy blowby will overwhelm
the PCV system>
Well, yes, all undoubtedly true. But this has never been part of the
discussion. What has any of that got to do with your contention of
reduction in gas mileage from a plugged PCV valve? The Car Talk guys
haven't said that at all.
George Macdonald
<teggerati...@changetheobvious.invalid> wrote:
>George Macdonald <fammacd=!SPAM^noth...@tellurian.com> spake unto the
>masses in news:oufac0t3919lbv113...@4ax.com:
>
>>
>> I know (think ?) we agreed that the PCV is a metered air leak. How
>> can it not affect engine efficiency and therefore fuel mileage?
>
>
>
>Because the air and blowby is coming from, and going to, the SAME PLACE AT
>ALL TIMES.
The valve "orifice" varies considerably according to the relative pressure
of manifold and crankcase
>Go take a good hard look at your own PCV system. See where the crankcase
>takes in air. See where the PCV valve dumps its air. Notice that BOTH are
>located in the INTAKE tract, mere inches from each other?
Go take a *good* look at the path the air, then air+blow-by gas takes in a
Honda system with breather box: air comes in from upstream of the throttle
butterfly through a tube to the valve cover, gets mixed with blow by gas,
sucked into the breather box mounted low on the block and up through the
PCV valve into the manifold. Later models just have the PCV valve mounted
on the valve cover.
>There is NO "air leak".
Yes - it's a metered air leak according to the variable orifice of the PCV.
>The valve does NOT introduce new air into the system.
The air comes from upstream of the throttle - within the operating
parameters of the engine that's atmospheric pressure, minus a little for
the air filter restriction. I dunno what you mean by "new air" but that's
air that the ECU has not measured - it has bypassed the primary device for
signalling mass air flow to the ECU: the throttle and its position sensor.
I'd doubt it has any effect on the IAT or MAP sensors either.
>It simply meters the existing air so as to ensure that there is POSITIVE
>flow through the crankcase, resulting in a constant changeover of the air
>in the crankcase, with any blowby gases routed back through the combustion
>chamber again.
>
>A blocked PCV Valve but a free breather will cause the gases to cavitate
>inside the crankcase. Since the breather will be under slight depression
>from the intake tract, pressure will be higher in the crankcase than the
>intake, so excess gases will get pushed into the intake and recycled
>through the combustion chamber again, just as if they went through the PCV
>properly, but there will be be no positive flow.
The pressure at the air intake end of the breather is highly dependent on
the throttle opening - when closed it's essentially atmospheric as
mentioned above. That is also now a different path to the induction
system... past the throttle valve and there's no air mixed with the blow-by
gas. IOW you've lost the metered air-leak.
You will not be able to operate an engine in that condition for long before
you have serious problems with the intake manifold and its various
precision components, chambers and narrow tubes. Your throttle butterfly
is going to get in a helluva mess and the rubber intake tube is not oil
resistant rubber - it'll rot.
>The main purpose of the PCV valve is to ensure that one end of the breather
>system always has a lower pressure than the other, so that one end will
>always be an intake, and one will always be an outlet. That is why it has a
>variable orifice.
>
>
>
>> BTW
>> I'm quite sure that a PCV can fail in more ways than getting plugged
>> up - e.g. the spring can get gunked up and bind.
>
>
>
>How is this different from being "plugged up"?
>
>The PCV plunger is surrounded by the spring. The metered orifice is the
>SPACE around the coils of the spring. If the spring gets gunked up, then
>the orifice is reduced, becuase the orifice IS around the spring.
If the spring binds, the valve may not be able to float and jam in the
fully open or fully closed position... or anything in between. Most likely
it will float and stick intermittently initially.
>> The PCV lives an
>> environment which is not kind to metal or even plastics.
>
>
>
>And it is made of metal and oil-compatible plastics. You don't think they
>would think of doing that?
Take a look at a used one - there's oil emulsion (acids), lacquering and
even fine particulates in there. Combustion gases mixed with oil mist and
water vapor takes more than "oil compatible" materials to stand up.
>>
>> I'm quite sure that the reason the rubber plug at the end of the
>> exhaust camshaft of an Integra, next to the distributor, gets pushed
>> out is because of crankcase pressure increase. It seems to happen
>> more in Winter when the PCV can get frozen up.
>
>
>
>It happens because the rubber gets old and has reduced holding power,
>especially when cold. It is only really clamped in place by the two little
>ridges on it anyway. This explained to me by my Japanese mechanic. I
>replaced my leaky old one a few years ago. It has not leaked since.
Absolutely not. You can put a new plug in, in say October, and it'll be
pushed out slightly by end of Winter. The rubber is not old or perished in
any way. I do not need some mechanic to explain to me how this works -
I've replaced the plug twice myself and seen the condition of the rubber on
two different cars. In fact I suspect that just cleaning up the old plug
would work as well as a new one - once the oil has worked its way past the
ribs on the plug, which is BTW only encouraged by pushing it back in, it
has established a path to escape.
>In order for pressure to build to the point where it could possibly "push
>the plug out", BOTH the PCV AND the breather MUST be blocked.
Take your oil filler cap off with the engine running and feel the pulsing
of err, pressure. It is not a static even pressure. Note that pulsing is
there even if you had no blow-by at all and in all engines except for a
very few V configurations; add in blow-by and reduced capacity to extract
it and the pressure oscillation is increased as well as the max crankcase
pressure.
If both breather and PCV were blocked you'd blow out seals in a very short
space of time.
Philip®
> "Caroline" <caroline1...@earthlink.net> spake unto the
> masses in
> news:BmSxc.8651$uX2....@newsread2.news.pas.earthlink.net:
>
>
>
> Note to Caroline: This time, please do not remove the
> cross-posting. I want as many minds involved in this debate as
> possible.
Fer Pete's Sake, TeGGeR, let it die. Crossposting is classic
trolling.
--
- Philip @ Maximum Torque RPM
Caroline
> "Caroline" <caroline1...@earthlink.net> spake
> Note to Caroline: This time, please do not remove the cross-posting. I want
> as many minds involved in this debate as possible.
I want misinformation (yours) spread as little as possible.
I'll try to respond to those who join us here at rec.autos.makers who seem to be
in the know, rational, open-minded, and who haven't had a response from others.
You can quote away in the other newsgroups. At some point, it's likely I'll
provide all the citations I provided earlier to help persuade people of the
truth that a malfunctioning PCV valve may (1) affect fuel economy and (2) may
cause excessive crankcase pressures, causing certain oil seals to fail
prematurely.
> > "Tegger®" <teggerati...@changetheobvious.invalid> wrote
> >> "Caroline" <caroline1...@earthlink.net> spake
> >> > For the rational among us trying to learn about pressure: Think of
> >> > the crankcase as a bucket of water being fed with a hose but also
> >> > having two holes in the bottom of it. The rate of water flow and
> >> > the hole sizes are such that 4 inches of water are maintained in
> >> > the bucket with this setup. If one suddenly plugs one of the holes,
> >> > what happens to the water level in the bucket?
>
> >> A much more accurate analogy:
> >> Imagine a bucket with ONE hole in the bottom (NEVER plugged).
> >
> > = the breather hose (which is far far less likely to become plugged
> > than the PCV valve)
snip junk
> If our analogy is to be the bucket with a hole in the bottom, then the top
> of the bucket is the throttle inlet and the bottom of the bucket is the
> intake valve.
This does not work, as it does nothing to explain what is happening in the
crankcase.
> The PCV system has nothing to do with either the throttle or the intake
> valve.
If one is going to consider in detail the relative pressures involved, yes it
does.
> It simply redirects some of the clean intake gas to the crankcase,
... at low load on 91 Honda Civics (among other models) via the breather hose.
Agreed.
> where it picks up blowby, and then directs it back to the intake again
... via a PCV valve which meters the flow according to intake manifold vacuum.
At low load and with a PCV valve that has failed shut (for whatever reasons),
you're assuming that the flow described above reverses. But you can't assume the
breather hose can accomodate the blow by the way the PCV valve can.
Just because the pressure in the crankcase is now higher than where the breather
hose connects to the air intake does not at all mean the crankcase will be
purged to the same extent it is with a correctly functioning PCV valve.
> My anology (countering your erroneous one) has two holes in the side of the
> bucket, both in the water, but one above the other with a hose connecting
> the two. Absent the blowby, that IS a PCV system. It's just a redirector.
I still have no idea what denotes crankcase pressure in your system.
> The PCV system does not go to a second intake valve, which is what you
> conceptually imply with YOUR analogy of a bucket with two holes in the
> bottom.
My analogy illustrates flow directions and relative pressures correctly for a
1991 Honda Civic (and no doubt other Hondas) at WOT (wide open throttle). Yours
doesn't illustrate it at any load, from what I can tell.
> > Your pressure relationships do not mimic those in an actual PCV
> > system.
>
> Neither do yours. Your bucket analogy consists of a non-compressible fluid
> (water) being PUSHED into a container (bucket).
Again, my model assumes the level of the water denotes crankcase pressure.
Note: My model is only for the purposes of illustrating why crankcase pressure
may rise with a plugged PCV valve. It does not capture all the nuances of a PCV
system.
> The actual intake system of
> a car uses a compressible fluid which is SUCKED into the engine.
>
> The intake tract pressure is ALWAYS less than ambient with the engine
> running. Hence, in a normal engine, there is ordinarily SUCTION at BOTH
> ends of the PCV system.
Nope. On a 1991 fuel injected Civic (as well as other cars):
At low throttle:
--breather hose flow is from air intake (near the air filter) to the crankcase.
-- PCV hose flow is from crankcase to air intake (near the cylinders' air
intake valves)
At wide open throttle:
-- breather hose flow is from crankcase to the air intake (near the air filter)
-- PCV hose flow is zero, because the PCV valve is shut.
http://tinyurl.com/yrq9s (Autozone repair guide) says this, too. It reproduces
exactly what is said in my Chilton's manual for 1991 Civics. Note: Figure 1 at
this site is also for 1991 1.5 Liter FI Civics.
> It is necessary to use a restrictor valve to lower
> pressure at one end to make sure the flow is always in one direction.
>
> That's the PCV valve.
>
> Are you familiar with the venturi principle? That's all the PCV valve does.
Wrong.
The PCV valve does not employ the Venturi principle. Flow through the valve is
due merely to (1) the appropriate pressure differential that causes the valve's
control mechanism to open it; and (2) a pressure difference from crankcase to
PCV valve outlet (which would cause fluid flow through any hose/pipe/whatever).
Practical application of the Venturi principle generally involves two different
flows of fluids. Fluid 1 will pass through an orifice (a.k.a. Venturi channel)
of some kind. The orifice increases Fluid 1's velocity but reduces the pressure
(conservation of energy; Bernoulli principle). Near the discharge of the
orifice, Fluid 2 enters via a connected pipe (or hose, or whatever). Fluid 1
draws Fluid 2 into its flow, and they now mix together.
Parts of carburetors, for one, use the Venturi principle to draw gasoline flow
(Fluid 2) into the flow of fresh air (Fluid 1).
There is no such setup in the PCV system.
> <snip quotes from TV personalities saying that heavy blowby will overwhelm
> the PCV system>
>
> Well, yes, all undoubtedly true. But this has never been part of the
> discussion.
In this part of the thread, we were only discussing how crankcase pressure may
rise above normal (on average) with a plugged PCV valve.
I see you are now conceding this point.
> What has any of that got to do with your contention of
> reduction in gas mileage from a plugged PCV valve?
That's another part of the thread. I have not joined this, as we did in fact
discuss this to some extent a few weeks ago. My citations and summary
explanations speak for themselves. But you want to re-engage, so...
You are convinced the ECU's proper functioning in open and closed loop has no
dependence on how the correct operation of the PCV valve.
I on the other hand am convinced that in either open loop, closed loop, or both,
the ECU's proper functioning depends on a certain design flow through the PCV
valve. For example, with a failed shut PCV valve, the ECU has planned for a
certain response to (intake) manifold air pressure changes *assuming* a certain
flow through the PCV valve is occurring.
You seem to be rebutting, "But in closed loop (O2 sensor in play, providing
feedback), if the response is 'wrong,' the O2 sensor will see the wrong level of
O2 in the exhaust and send a (too rich) feedback signal to the ECU. The ECU will
adjust the air/fuel ratio for optimal economy."
But how does the ECU do this? In my 1991 fuel injected Civic, the ECU uses
signals from the MAP (manifold air pressure) sensor and crank angle sensor to
control fuel injector "basic discharge duration." The ECU's memory has pre-set,
fixed fuel injector "basic discharge durations" depending on these two inputs.
The fact that these basic discharge durations are pre-set and fixed means they
assume a certain flow from the PCV valve is present.
The O2 sensor's signal (among other sensors' signals) will modify the basic
discharge duration somewhat, but the engine is still stuck with a particular,
basic discharge duration. The pre-set values are not appropriate for a no-flow
condition through a malfunctioning PCV valve.
http://tinyurl.com/22d46 describes the general setup of a 91 Civic LX Programmed
Fuel Injection system. The remarks above about "basic discharge duration," etc.
derive from it and my own engineering experience.
The above is one explanation of why in closed loop fuel economy may be bad with
a malfunctioning PCV valve.
Caroline
snip
> If the spring binds, the valve may not be able to float and jam in the
> fully open or fully closed position... or anything in between. Most likely
> it will float and stick intermittently initially.
I concur with this analysis of what may happen when a PCV valve gets gunk in it.
"Clogging" may result in either a fail open, fail shut, or fail "intermediate"
condition.
The rest of George's analysis looks fine to me as a general description. I do
note that, for one, the 1991 Civic does not, from what I can tell, have a mass
air flow sensor. The car (like many cars) has other minor idiosynchrasies that
distinguish it from George's description.
I hope we all agree that there is some variation from one car model's PCV system
to another and so are somewhat generous when reviewing descriptions of flow
directions, among other features.
Caroline
> My analogy illustrates flow directions and relative pressures correctly for a
> 1991 Honda Civic (and no doubt other Hondas) at WOT (wide open throttle).
Oops. Not.
At WOT, on the 91 Civic by design the PCV valve is shut, and crankcase gases by
design exit through the breather hose.
At non-WOT, on the 91 Civic by design the PCV valve is generally open at least
partly.
My model is simply illustrating that pressure will rise in the crankcase when an
ordinarily open escape path (the PCV valve or its hose) is blocked.
This is the same as blocking off one or more exit holes in the bottom of a
bucket of water previously being filled such that the rate of water entry = the
rate of water exit, and such that the system maintains a certain level of water
in the bucket. Goes ins = goes outs, as we used to say in the nuclear navy. But
block off an exit hole, and the level of water rises, just as average crankcase
pressure rises when blocking off the PCV line.
Tegger can argue that at WOT, the PCV valve is supposed to be fully shut, and
crankcase gases exit via the breather hose, by design. So a blocked PCV valve on
a 91 Civic has no effect at WOT.
But how often is a car at WOT?
Certainly not all the time.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
>snip
>> If the spring binds, the valve may not be able to float and jam in the
>> fully open or fully closed position... or anything in between. Most likely
>> it will float and stick intermittently initially.
>
>I concur with this analysis of what may happen when a PCV valve gets gunk in it.
>"Clogging" may result in either a fail open, fail shut, or fail "intermediate"
>condition.
>
>The rest of George's analysis looks fine to me as a general description. I do
>note that, for one, the 1991 Civic does not, from what I can tell, have a mass
>air flow sensor. The car (like many cars) has other minor idiosynchrasies that
>distinguish it from George's description.
Some mfrs, notably those with Bosch FI systems, use a mass airflow sensor -
often a hot-wire thermistor AFAIK. Honda derives mass flow, I assume in
the ECU programming, from throttle position, intake air temp and manifold
absolute pressure. Note that those actual measurements can also be used
for other programmable parameters of the ECU.
>I hope we all agree that there is some variation from one car model's PCV system
>to another and so are somewhat generous when reviewing descriptions of flow
>directions, among other features.
I think there are some which just have to be wrong though - possibly
outdated? IMO the Toyota doc (h63.pdf) looks the best explanation.
George Macdonald
<teggerati...@changetheobvious.invalid> wrote:
>George Macdonald <fammacd=!SPAM^noth...@tellurian.com> spake unto the
>masses in news:bc8fc0dfrepdi5jr1...@4ax.com:
>
>
>> Look I don't really care what your mechanic says. I've been told enough
>> guff by mechanics over the years to fill an encyclopaedia.
>
>
>
>So you throw the baby out with the bathwater. They're ALL bad, right?
They're not *all* bad - good ones who are honest with the customer are
rare... IME.
>> The computer hasn't measured the mass of leaked air
>
>
>
>It's NOT "leaked air". It's the very same air that has already passed by
>the throttle plate and the air flow meter.
No it has *not*. As already mentioned umpteen times, the breather tube
intake is *upstream* of the throttle plate; geez you told me to look at my
car but you haven't even done as much yourself! BTW there is no air flow
meter in the Honda systems that I've seen.
>All the PCV valve does is make sure that flow is always present, and always
>in one direction.
>
>This is the part nobody in this group seems to understand. Of course,
>nobody in this group is a working mechanic, either (me included). And some
>of them aren't even willing to listen to what working mechanics have to
>say.
I guess we just know better.:-) See above.
>> So your mechanics are right and the auto mfrs and engine designers are
>> all wrong.<shrug>
>
>
>
>Show me ANYWHERE where ANY auto mfr and engine designer says HOW MUCH the
>engine will "run rich" with a plugged PCV valve.
Not exactly but in the h63.pdf, a Toyota doc, it states quite plainly: "The
installation of an incorrect valve may cause engine stalling, rough idle
and other driveability complaints". It's not a big hop to conclude that a
malfunctioning PCV is an err, incorrect valve.
>I think you guys are all misunderstanding what those auto mfrs and engine
>designers are saying. Web pages don't count here.
Just RTFM... the service manual and apply a bit of scientifically informed
interpretation.
Caroline
> <caroline1...@earthlink.net> wrote:
> > I do
> >note that, for one, the 1991 Civic does not, from what I can tell, have a
mass
> >air flow sensor. The car (like many cars) has other minor idiosynchrasies
that
> >distinguish it from George's description.
>
> Some mfrs, notably those with Bosch FI systems, use a mass airflow sensor -
> often a hot-wire thermistor AFAIK. Honda derives mass flow, I assume in
> the ECU programming, from throttle position, intake air temp and manifold
> absolute pressure. Note that those actual measurements can also be used
> for other programmable parameters of the ECU.
Yes. Perhaps you're also getting at the fact that fuel/air ratio is not the only
closed loop controlled engine parameter. A certain Ford service manual I was
reading the other day noted that engine RPM control is also closed loop: The
actual RPM is fed back to the computer and compared to the desired RPM, and the
computer responds to adjust the RPM.
The overlap of these closed loop engine control systems is inevitable of course.
The modeling is sophisticated and probably proprietary. The latter comment is
based in part on having known a few PhD'd Ford control systems engineers who
work on emissions control design and implementation of the same. Not trying to
name drop; just trying to say there are of course people who have specific
model's full ECU control system model on paper (er, computer) and could give a
very precise and practical answer as to how the ECU responds to different
changes for that model. But access to this info by the public is difficult or
impossible. Plus, I for one no longer have access to a computer or software
capable of handling simulation of such complex models that might offer more
insight into the interactions of the systems.
So I think analyses here of how the ECU controls the engine can only be at a
very basic level.
> >I hope we all agree that there is some variation from one car model's PCV
system
> >to another and so are somewhat generous when reviewing descriptions of flow
> >directions, among other features.
>
> I think there are some which just have to be wrong though - possibly
> outdated? IMO the Toyota doc (h63.pdf) looks the best explanation.
For Toyotas, I agree. But one item that I think is impeding analysis here is
whether the PCV valve is wide open or fully shut at wide open throttle (WOT). I
am convinced (for now) that this does vary from one car make, model, and year to
another. All the designs still accomplish the same thing--removing crankcase
gases. But they are engineered differently. (I expect you know all this, but for
the sake of the written record... )
In support of this, at the library the other day I pulled down several car
makers' Chilton manuals. It's easy to turn to the first few pages of Section 4
"Emissions" to see specifically whether the PCV valve was wide open or fully
shut at WOT. Some of the manuals are a little vague on this point. Others are
not.
All or at least several models of Hondas and the early 1990s Acuras have the
PCV valve fully shut at WOT. The manuals explicitly add that the crankcase gas
flow at WOT is then exclusively out the breather hose to the air intake
(upstream of the throttle, like you noted in your other, recent post). Because
of this explicit statement, it does not seem like this is a mistake. It could
be. As you say, the manuals do have mistakes. But I'm not yet convinced.
By contrast, the reports for Toyotas (and some other makes) I've seen have the
PCV valve fully open at WOT.
Pressure differential and flow-wise, both the Toyota explanations and the Honda
explanations appear to me to be rational. Truly intelligent commentary on why in
one the PCV valve is shut and in the other it is open might demand more inside
knowledge of the systems than is available.
IIRC Mitsubishi engineers its PCV system setup quite differently from the other
manufacturers I read.
As your Toyota document http://www.autoshop101.com/forms/h63.pdf shows, some PCV
systems use a fixed orifice instead of a PCV valve. The orifice of course is not
as precise at metering in accord with engine load.
SHO Ford Tauruses from 1986-1995 do not even have a PCV valve nor apparently
orifice. (I was recently helping a relative with fuel mileage concerns on his
Taurus, thus I've been reading about its PCV system design too.)
I suspect the extent to which fuel mileage may be affected by a malfunctioning
PCV system will vary, and possibly quite a lot, from one car make to another.
Nonetheless, for the readers here, my understanding is that a properly
functioning PCV system first and foremost ensures the crankcase vapors are kept
to a minimum. I'd say at a minimum for all cars the engine oil may become
dirtier sooner with a malfunctioning PCV system. This by itself warrants its
inspection and/or replacement as a routine maintenance item. If fuel mileage
drops off, it's also certainly worth considering replacement/cleaning of the PCV
valve.
Treatise over.
George Macdonald
True and I don't have inside info on those particular aspects of auto
design for any mfr. I'm pretty sure though that after all the theoretical
behaviors have been modeled and optimized, the production model programming
of the ECU is subject to fine adjustments based on empirical testing for
low emissions.
>> >I hope we all agree that there is some variation from one car model's PCV
>system
>> >to another and so are somewhat generous when reviewing descriptions of flow
>> >directions, among other features.
>>
>> I think there are some which just have to be wrong though - possibly
>> outdated? IMO the Toyota doc (h63.pdf) looks the best explanation.
>
>For Toyotas, I agree. But one item that I think is impeding analysis here is
>whether the PCV valve is wide open or fully shut at wide open throttle (WOT). I
>am convinced (for now) that this does vary from one car make, model, and year to
>another. All the designs still accomplish the same thing--removing crankcase
>gases. But they are engineered differently. (I expect you know all this, but for
>the sake of the written record... )
>
>In support of this, at the library the other day I pulled down several car
>makers' Chilton manuals. It's easy to turn to the first few pages of Section 4
>"Emissions" to see specifically whether the PCV valve was wide open or fully
>shut at WOT. Some of the manuals are a little vague on this point. Others are
>not.
>
>All or at least several models of Hondas and the early 1990s Acuras have the
>PCV valve fully shut at WOT. The manuals explicitly add that the crankcase gas
>flow at WOT is then exclusively out the breather hose to the air intake
>(upstream of the throttle, like you noted in your other, recent post). Because
>of this explicit statement, it does not seem like this is a mistake. It could
>be. As you say, the manuals do have mistakes. But I'm not yet convinced.
Chilton's manual says this? They are notorious for being full of mostly
generic info/pages supplemented by a few token pages for the specific model
at hand. The one I got for my VW Beetle had a section on replacing
coolant.<shrug>
I have Helm manuals for '88 Integra, '90 Civic, '92 Integra, '99 Integra
and 2K Accord and none of them go into details on exact behavior of the PCV
valve - all have just the simple hose pinch check for verification of
functionality. I'd like to know where Chiltons got their info from and how
they arrive at their conclusion - frankly I have my doubts about their
accuracy.
>By contrast, the reports for Toyotas (and some other makes) I've seen have the
>PCV valve fully open at WOT.
>
>Pressure differential and flow-wise, both the Toyota explanations and the Honda
>explanations appear to me to be rational. Truly intelligent commentary on why in
>one the PCV valve is shut and in the other it is open might demand more inside
>knowledge of the systems than is available.
The illustrations of PCVs in the Honda Helm manuals, though small, look
very similar to the one in the Toyota h63.df doc, with a pintle being
sucked at high manifold vacuum into a restricted neck, floating somewhere
in the middle of its travel at low load cruising and being very close to
closed at high load. That last condition where the spring is *almost*
fully extended provides the least restriction at the pintle end of the
valve and therefore the highest flow of blow-by gas.
Toyota notes that in that last condition, if blow-by exceeds the PCV's
ability to flow the gases, they will take the route of the breather hose.
This all makes sense to me.
>IIRC Mitsubishi engineers its PCV system setup quite differently from the other
>manufacturers I read.
>
>As your Toyota document http://www.autoshop101.com/forms/h63.pdf shows, some PCV
>systems use a fixed orifice instead of a PCV valve. The orifice of course is not
>as precise at metering in accord with engine load.
>
>SHO Ford Tauruses from 1986-1995 do not even have a PCV valve nor apparently
>orifice. (I was recently helping a relative with fuel mileage concerns on his
>Taurus, thus I've been reading about its PCV system design too.)
>
>I suspect the extent to which fuel mileage may be affected by a malfunctioning
>PCV system will vary, and possibly quite a lot, from one car make to another.
>
>Nonetheless, for the readers here, my understanding is that a properly
>functioning PCV system first and foremost ensures the crankcase vapors are kept
>to a minimum. I'd say at a minimum for all cars the engine oil may become
>dirtier sooner with a malfunctioning PCV system. This by itself warrants its
>inspection and/or replacement as a routine maintenance item. If fuel mileage
>drops off, it's also certainly worth considering replacement/cleaning of the PCV
>valve.
I'll add that a PCV which is not allowing sufficient flow is going to cause
accelerated deterioration of the components of the induction system: the
rubber intake hose, throttle valve, EACV, fast idle valve and any other
vacuum driven items. Besides the usual hose pinch check, it's also worth
checking the rubber intake hose where the breather pipe enters it for oily
emulsified mess as a guide to whether the PCV needs replaced.
>Treatise over.
Chiltons notwithstanding, I think we're in agreement.:-)
Caroline
Absolutely.
I recall the academic folks I mention above giving Christmas presents to the
techs in the Ford motors emission controls labs, where new "on paper/computer"
designs and theory were being implemented. They all worked that closely. (Not
sure how they got along, but they definitely had verbal communications.)
snip
> >All or at least several models of Hondas and the early 1990s Acuras have the
> >PCV valve fully shut at WOT. The manuals explicitly add that the crankcase
gas
> >flow at WOT is then exclusively out the breather hose to the air intake
> >(upstream of the throttle, like you noted in your other, recent post).
Because
> >of this explicit statement, it does not seem like this is a mistake. It could
> >be. As you say, the manuals do have mistakes. But I'm not yet convinced.
>
> Chilton's manual says this?
Yes. The Autozone online repair guides repeat it.
> They are notorious for being full of mostly
> generic info/pages supplemented by a few token pages for the specific model
> at hand. The one I got for my VW Beetle had a section on replacing
> coolant.<shrug>
I've never had a Helm manual in my hands. Someone here recently said the manual
pages accessible via
http://www.honda.co.uk/owner/workshopmanuals2.html were identical to Helm. While
I realize manuals in general are full of errors (inaccuracies?), I don't see
anymore in my Chilton's than I do at the link above.
One matter over which I'm a little anal right now is how neither Chilton's nor
the UK site manuals above talk about removing the cruise control actuator for
their 1991 Hondas in the timing belt instructions. The UK site manuals only seem
to have caught onto the necessity of this step in the 1995 or so model year
Hondas. (Haven't checked the 1996 Chilton manuals yet.)
OTOH, you have been reading these various manuals longer than I and have the
Helm manual in your hands, so of course I recommend readers defer to your
experience on this.
> I have Helm manuals for '88 Integra, '90 Civic, '92 Integra, '99 Integra
> and 2K Accord and none of them go into details on exact behavior of the PCV
> valve -
They don't say that the opening of the PCV valve is proportional to intake
manifold vacuum?
E.g. from http://www.honda.co.uk/owner/CivicManual/pdf/11-109.pdf for 1995-1997
Civics:
"When the engine starts, the plunger in the PCV Valve is lifted in proportion to
intake manifold vacuum... "
> all have just the simple hose pinch check for verification of
> functionality. I'd like to know where Chiltons got their info from and how
> they arrive at their conclusion - frankly I have my doubts about their
> accuracy.
Not to drag this out too much, but I'm figuring at the moment that at WOT,
-- blowby gas production is at its maximum.
-- average crankcase pressure is likely at its maximum
Where things become confusing is when assessing the pressures at
-- the breather hose's connection to the air intake, just upstream of the
throttle. This absolute pressure should decrease as the throttle is opened.
-- the PCV valve connection to the air intake, downstream of the throttle
(should be a varying vacuum; lower vacuum = higher abs. pressure at WOT, at
least for Honda's systems)
I figure on Hondas, at WOT, the differential pressure from crankcase to breather
hose connection meters (or just accomodates) the flow well, by design. The Honda
PCV valve shuts.
On Toyotas at WOT, the differential pressure operating the PCV valve and the
valve design meters the flow well. The Toyota PCV valve stays open at WOT(??)
but is assisted by the breather hose?
> >By contrast, the reports for Toyotas (and some other makes) I've seen have
the
> >PCV valve fully open at WOT.
> >
> >Pressure differential and flow-wise, both the Toyota explanations and the
Honda
> >explanations appear to me to be rational. Truly intelligent commentary on why
in
> >one the PCV valve is shut and in the other it is open might demand more
inside
> >knowledge of the systems than is available.
>
> The illustrations of PCVs in the Honda Helm manuals, though small, look
> very similar to the one in the Toyota h63.df doc, with a pintle being
> sucked at high manifold vacuum into a restricted neck, floating somewhere
> in the middle of its travel at low load cruising and being very close to
> closed at high load.
To be very clear, I recognize two valve "seats" in the PCV valve. The Toyota
drawing's bottom seat is pretty much an "all or nothing" seat design. The Toyota
drawing's upper seat is designed to regulate in accord with pintle position.
So above I hope you mean the bottom of the pintle in the drawings at high load
is almost touching its seat. At the same time, the top portion of the pintle's
location is such that the second, upper valve passage is as wide open as
possible.
As load increases and the bottom of the pintle nears the bottom in the drawings,
the flow through the valve may be followed by tracing the valve flow
characteristic curve (page 2) leftwards, until the peak valve flow is reached.
Continuing left there is a quick dropoff on the curve.
The Toyota valve's flow always stays above the blowby curve?
The Honda valve's flow drops below the blowby curve.
Unless of course Honda Chilton's is all screwed up.
> That last condition where the spring is *almost*
> fully extended provides the least restriction at the pintle end of the
> valve and therefore the highest flow of blow-by gas.
Agreed.
> Toyota notes that in that last condition, if blow-by exceeds the PCV's
> ability to flow the gases, they will take the route of the breather hose.
> This all makes sense to me.
Same here, except the Toyota site isn't clear about whether the PCV valve
actually closes (as its characteristic curve implies, somewhat) at WOT.
snip
> I'll add that a PCV which is not allowing sufficient flow is going to cause
> accelerated deterioration of the components of the induction system: the
> rubber intake hose, throttle valve, EACV, fast idle valve and any other
> vacuum driven items.
Due to oily acidic(?) exhaust compounds accumulating on parts?
> Besides the usual hose pinch check, it's also worth
> checking the rubber intake hose where the breather pipe enters it for oily
> emulsified mess as a guide to whether the PCV needs replaced.
> >Treatise over.
>
> Chiltons notwithstanding, I think we're in agreement.:-)
Yes.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
<<snip>>
>> Chilton's manual says this?
>
>Yes. The Autozone online repair guides repeat it.
>
>> They are notorious for being full of mostly
>> generic info/pages supplemented by a few token pages for the specific model
>> at hand. The one I got for my VW Beetle had a section on replacing
>> coolant.<shrug>
>
>I've never had a Helm manual in my hands. Someone here recently said the manual
>pages accessible via
>http://www.honda.co.uk/owner/workshopmanuals2.html were identical to Helm. While
>I realize manuals in general are full of errors (inaccuracies?), I don't see
>anymore in my Chilton's than I do at the link above.
Yes, those pages resemble the Helm manuals... because the Helm manuals are
actually Honda manuals. Helm just handles printing/binding in some cases
and distribution.
>One matter over which I'm a little anal right now is how neither Chilton's nor
>the UK site manuals above talk about removing the cruise control actuator for
>their 1991 Hondas in the timing belt instructions. The UK site manuals only seem
>to have caught onto the necessity of this step in the 1995 or so model year
>Hondas. (Haven't checked the 1996 Chilton manuals yet.)
It's not in my Helm manuals for '90 and '92 either.
>OTOH, you have been reading these various manuals longer than I and have the
>Helm manual in your hands, so of course I recommend readers defer to your
>experience on this.
>
>> I have Helm manuals for '88 Integra, '90 Civic, '92 Integra, '99 Integra
>> and 2K Accord and none of them go into details on exact behavior of the PCV
>> valve -
>
>They don't say that the opening of the PCV valve is proportional to intake
>manifold vacuum?
>
>E.g. from http://www.honda.co.uk/owner/CivicManual/pdf/11-109.pdf for 1995-1997
>Civics:
>"When the engine starts, the plunger in the PCV Valve is lifted in proportion to
>intake manifold vacuum... "
Yes, but I mean more details: lift does not necessarily translate into more
flow, as we know.
>> all have just the simple hose pinch check for verification of
>> functionality. I'd like to know where Chiltons got their info from and how
>> they arrive at their conclusion - frankly I have my doubts about their
>> accuracy.
>
>Not to drag this out too much, but I'm figuring at the moment that at WOT,
>
>-- blowby gas production is at its maximum.
>-- average crankcase pressure is likely at its maximum
>
>Where things become confusing is when assessing the pressures at
>
>-- the breather hose's connection to the air intake, just upstream of the
>throttle. This absolute pressure should decrease as the throttle is opened.
>
>-- the PCV valve connection to the air intake, downstream of the throttle
>(should be a varying vacuum; lower vacuum = higher abs. pressure at WOT, at
>least for Honda's systems)
I don't think either of the above are that important at WOT - with the
throttle valve open there's no pressure drop across it.
>I figure on Hondas, at WOT, the differential pressure from crankcase to breather
>hose connection meters (or just accomodates) the flow well, by design. The Honda
>PCV valve shuts.
>
>On Toyotas at WOT, the differential pressure operating the PCV valve and the
>valve design meters the flow well. The Toyota PCV valve stays open at WOT(??)
>but is assisted by the breather hose?
In both cases, the only criteria I see here are the spring tension when
it's fully extended and the restriction against flow through the breather
tube due to its diameter - the crankcase pressure has to rise sufficiently
to lift the spring off its seat for the gas to make its way through the PCV
valve... remembering that with the engine off the PCV has to be closed.
I haven't seen the Chilton curve but I'll project it through my prejudice
of Chilton's manuals.:-)
>> That last condition where the spring is *almost*
>> fully extended provides the least restriction at the pintle end of the
>> valve and therefore the highest flow of blow-by gas.
>
>Agreed.
>
>> Toyota notes that in that last condition, if blow-by exceeds the PCV's
>> ability to flow the gases, they will take the route of the breather hose.
>> This all makes sense to me.
>
>Same here, except the Toyota site isn't clear about whether the PCV valve
>actually closes (as its characteristic curve implies, somewhat) at WOT.
It seems pretty clear from the text and the illustration that it is nearly
closed and you get "maximum flow of blowby."
Bozo
>> Bad analogy. Water is not air. Water cannot change density.
>
>
If water does not change it's density, why does ice float???
Probably you meant that water can not be compressed.
Andrew
Bozo <nos...@spam.com> wrote in message
<opr9lnkbawfwcok5@martin>
> >>
> >> Bad analogy. Water is not air. Water cannot change density.
> >
> >
>
> If water does not change it's density, why does ice float???
>
> Probably you meant that water can not be compressed.
Well, it ain't easy, but that's wrong too, take some work, but
liquids can be compressed too<grin>
http://www.newton.dep.anl.gov/askasci/chem00/chem00101.htm
--
Composed with Newz Crawler 1.7 http://www.newzcrawler.com/
Bozo
wrote:
>
> Well, it ain't easy, but that's wrong too, take some work, but
> liquids can be compressed too<grin>
>
> http://www.newton.dep.anl.gov/askasci/chem00/chem00101.htm
I guess if we are talking 'black holes' then you are 100% right (grin)
Andrew
Bozo <nos...@spam.com> wrote in message
<opr9pem2lvfwcok5@martin>
> wrote:
>
> >
> >
> > http://www.newton.dep.anl.gov/askasci/chem00/chem00101.htm
>
Absolutely! Alt fuel source and I'm sure I carry one in my wallet!
Caroline
> > If water does not change it's density, why does ice float???
> > Probably you meant that water can not be compressed.
>
> Well, it ain't easy, but that's wrong too, take some work, but
> liquids can be compressed too<grin>
>
> http://www.newton.dep.anl.gov/askasci/chem00/chem00101.htm
Or a person can take a peek at the inlet and outlet hoses on a car's power
steering pump.
Guess why the outlet hose's diameter is smaller.
Liquids can be compressed. For many applications, it's not a trivial design
consideration.
Bozo
<caroline1...@earthlink.net> wrote:
> Or a person can take a peek at the inlet and outlet hoses on a car's
> power
> steering pump.
>
> Guess why the outlet hose's diameter is smaller.
>
> Liquids can be compressed. For many applications, it's not a trivial
> design
> consideration.
Sorry, but I don't think so in this case. When the pump is sucking from
the resevoir (open to atmosphere) the most suction possible is 1 bar (1
atmosphere), however on the output side, the pressure is as high as the
pump is capable of (less any pressure release valve etc), hence the
smaller diameter. In everyday applications, one can normally assume that
liquids don't compress enough to make much difference. However
temperature can have huge effects with both viscosity and themal expansion
changes, and working fluids (power steering fluid, A/T & engine oil) will
increase their temperature.
Leon
<caroline1...@earthlink.net> wrote:
Wow, compressible fluid flow at the power steering pump, so compressible
that the outlet is smaller. I never thought of that.
Well, next time I buy brake fluid, I'll make sure it's the expensive stuff
because the cheap fluid can be compressed and make my brakes feel spongy.
--
Bye,
Leon
Caroline
> <caroline1...@earthlink.net> wrote:
> > Or a person can take a peek at the inlet and outlet hoses on a car's
> > power
> > steering pump.
> >
> > Guess why the outlet hose's diameter is smaller.
> >
> > Liquids can be compressed. For many applications, it's not a trivial
> > design
> > consideration.
>
>
> Sorry, but I don't think so in this case. When the pump is sucking from
> the resevoir (open to atmosphere) the most suction possible is 1 bar (1
> atmosphere),
It's the pressure change across the pump that's important.
Note: 1 bar does not equal 1 atmosphere. It's close, but no cigar.
> however on the output side, the pressure is as high as the
> pump is capable of (less any pressure release valve etc),
Less any pressure relief valve?
If the pump has a pressure relief valve and it's open, the pump is not operating
in a normal condition.
> hence the
> smaller diameter.
You do know that the density of the liquid and its pressure are directly
correlated, right? Given that
-- mass flow = density * pipe cross-sectional area * velocity
-- mass flow in = mass flow out
-- velocity is fixed by pipe and pump material considerations
-- pressure is higher at the outlet (otherwise it's not a pump), so the liquid's
density at the outlet is higher
what conclusion can one rationally draw? The cross-sectional area must be
smaller at the pump outlet.
> In everyday applications, one can normally assume that
> liquids don't compress enough to make much difference.
If by "everyday applications" you mean those pumps that cause small pressure
rises, I agree it's fair to assume the density is fixed.
But for pumps that cause large pressure rises, and depending on the particular
fluid, the compressibility of liquids is taken into account when determining
needed pump inlet and outlet pipe sizes.
See for example, http://www.koken-boring.co.jp/e/e_product/pump/mg/mgpump.htm ,
where a number of pumps and their specifications are shown. Note that, for the
higher pressure pumps, the outlet diameter is always smaller than the inlet
diameter.
On my Honda's power steering pump, I just "miked" the diameters (= measured with
a micrometer), and the outlet is about 0.075 inch smaller in diameter than the
inlet. The difference is visible to the naked eye.
Caroline
> <caroline1...@earthlink.net> wrote:
> > Or a person can take a peek at the inlet and outlet hoses on a car's
> > power
> > steering pump.
> >
> > Guess why the outlet hose's diameter is smaller.
> >
> > Liquids can be compressed. For many applications, it's not a trivial
> > design
> > consideration.
> >
> >
>
> Wow, compressible fluid flow at the power steering pump, so compressible
> that the outlet is smaller. I never thought of that.
>
> Well, next time I buy brake fluid, I'll make sure it's the expensive stuff
> because the cheap fluid can be compressed and make my brakes feel spongy.
Are you funnin' me? ;-)
I have no idea if the expensive brake fluid is superior from a compressibility
standpoint and whether that even has a detectable effect when operating the
brakes.
Bozo
<caroline1...@earthlink.net> wrote:
> Note: 1 bar does not equal 1 atmosphere. It's close, but no cigar.
>
As a rough and ready engineer I love approximations, and so for me 1 bar
is about 1 atmosphere.
Same as 10N is about 1Kgf when doing rough and ready maths (I know it
isn't, and if doing calculations I use the accurate figures).
>
> -- mass flow = density * pipe cross-sectional area * velocity
> -- mass flow in = mass flow out
> -- velocity is fixed by pipe and pump material considerations
> -- pressure is higher at the outlet (otherwise it's not a pump), so the
> liquid's
> density at the outlet is higher
or the velocity is higher, hence the same mass flow.
As I said before, I was only working in approximations, however, if you
wish to measure the smallest amount of compression, then everything is
compressible.
Even better is that in fluidics a gas is considered a fluid, and that is
most certainly compressible.
Anyway, I accept that are correct.
Caroline
> <caroline1...@earthlink.net> wrote:
>
> > Note: 1 bar does not equal 1 atmosphere. It's close, but no cigar.
> >
> As a rough and ready engineer I love approximations, and so for me 1 bar
> is about 1 atmosphere.
I don't know what you mean by "rough and ready engineer," but I assure you,
bachelor's degreed and higher engineers involved in design do not use
approximations that are over 1% in error (as this one is) while designing.
(Not that "bachelor's degreed and higher engineers" are all necessarily
qualified to talk about automotive repairs and maintenance. I'd say most these
days are not.)
> Same as 10N is about 1Kgf when doing rough and ready maths (I know it
> isn't, and if doing calculations I use the accurate figures).
Are you in the United States?
I am. Never in my years of engineering (including teaching in colleges) have I
used the Kgf. Doing so seems to defeat the purpose of the metric system. Plus, I
personally wouldn't assume 10 N = 1 Kgf in design. It's off by about 2%.
These errors propagate and "mathematically grow."
Manned spaceships have crashed due to such silly, seemingly trivial mistakes.
> > -- mass flow = density * pipe cross-sectional area * velocity
> > -- mass flow in = mass flow out
> > -- velocity is fixed by pipe and pump material considerations
> > -- pressure is higher at the outlet (otherwise it's not a pump), so the
> > liquid's
> > density at the outlet is higher
>
> or the velocity is higher, hence the same mass flow.
You're ignoring my comment about material concerns.
Velocity is a big deal when it comes to preserving material integrity. Pump,
pipe, and most any design involving fluid flow will take velocities into
account.
> As I said before, I was only working in approximations, however, if you
> wish to measure the smallest amount of compression,
Nope. I wish to point out that a car's power steering pump inlet and outlet
lines are different sizes for a good reason.
This is not some pie-in-the-sky nitpicky point. The compressibility of liquids
has immediate practical implications, though I grant also that in many, but not
all, applications it is perfectly fine to assume a liquid is "essentially
incompressible."
For the layperson: If you're ever trying to figure out the inlet and outlet on
any sort of device that moves fluid and raises its pressure substantially, then
the line that is smaller will be the outlet, for all the aforementioned
reasons...
> then everything is compressible.
Bozo
<caroline1...@earthlink.net> wrote:
>
> I don't know what you mean by "rough and ready engineer," but I assure
> you,
> bachelor's degreed and higher engineers involved in design do not use
> approximations that are over 1% in error (as this one is) while
> designing.
ok i'll be serious - I too work to many decimal places when required,
however for newsgroup chatter I use approximations - This time a Big
mistake :-)
>
> (Not that "bachelor's degreed and higher engineers" are all necessarily
> qualified to talk about automotive repairs and maintenance. I'd say most
> these
> days are not.)
Agreed
>
>> Same as 10N is about 1Kgf when doing rough and ready maths (I know it
>> isn't, and if doing calculations I use the accurate figures).
>
> Are you in the United States?
>
Certainly not - UK
> I am. Never in my years of engineering (including teaching in colleges)
> have I
> used the Kgf. Doing so seems to defeat the purpose of the metric system.
> Plus, I
> personally wouldn't assume 10 N = 1 Kgf in design. It's off by about 2%.
>
Nor would I for design etc, but if somebody asked me how large a 100
newton force is, I would say about 10kg - I know this is wrong.
> These errors propagate and "mathematically grow."
>
Agreed
Anyway one thing I eventually learned at school was never disagree with
the teacher, and in this case you are right - smile it's meant as a joke
SoCalMike
> I don't know what you mean by "rough and ready engineer," but I assure you,
> bachelor's degreed and higher engineers involved in design do not use
> approximations that are over 1% in error (as this one is) while designing.
i dont think the OP was designing anything, and they admitted its not an
exact number.
<snip>
> These errors propagate and "mathematically grow."
called "tolerance stacking", innit?
Caroline
C wrote
> > These errors propagate and "mathematically grow."
>
> called "tolerance stacking", innit?
Hadn't heard that one. Nice. :-)
Caroline
> On Wed, 23 Jun 2004 21:36:25 GMT, Caroline
> ok i'll be serious - I too work to many decimal places when required,
> however for newsgroup chatter I use approximations - This time a Big
> mistake :-)
Nah. I was just "observating" with my original comment. It was only a
persnickety "note"... Or so it was meant to be.
> > Are you in the United States?
> >
> Certainly not - UK
lol
> Nor would I for design etc, but if somebody asked me how large a 100
> newton force is, I would say about 10kg - I know this is wrong.
Now that's not wrong. Ten kg in your hand is *about* a 10 newton force. Um, on
earth, anyway.
But you know this.
> > These errors propagate and "mathematically grow."
> >
> Agreed
>
> Anyway one thing I eventually learned at school was never disagree with
> the teacher, and in this case you are right - smile it's meant as a joke
I'm not the teacher but just some babe wondering last week which hose was the
inlet and which was the outlet on my power steering pump. :-)
Caroline
snip
> Ten kg in your hand is *about* a 10 newton force.
Uh oh...
Misterbeets
My guess is it is because of the differences in pressures and has nothing to
do with compressibility of the medium. For each atmosphere increase in
pressure, the volume of the water would only decrease by 46.4 parts per
million.
Bozo
Uh oh indeed.....................
>
George Macdonald
<caroline1...@earthlink.net> wrote:
Umm, here's a good reference site:
http://www.ex.ac.uk/Projects/trol/dictunit/dictunit.htm :-)
BTW on your comment about never using the Kgf, it appears all the time in
workshop manuals, even Honda ones and you'll find Kgf/cm² on many pressure
gauges in the U.S. Yes we are a backward country as far as SI units go but
mechanics and plumbers etc. can relate to a Kg or a cm² - they know what it
feels like and they like that and if they're going to be forced to metrify,
they prefer something err, tangible. You know the chassis design specs for
the Grandam Rolex racing series are all in inches and lbs - keeps them
furriners away... and none of the suckers are going to stray off into the
LeMans series.
We're also not alone in bastardized systems - all the Japanese and European
auto mfrs are now quoting engine brake power in pferdestärkes (ps) and one
of those is exactly 75 kilogram-force meters of work per second which
fortuitously works out to .9862bhp. So in this case, at one time, the
metric folks bent to the ubiquity of the imperial unit based bhp and
invented a metric measure which closely corresponded to it - ironic!
Caroline
C wrote about a car's power steering pump:
> > "Guess why the outlet hose's diameter is smaller."
>
> My guess is it is because of the differences in pressures and has nothing to
> do with compressibility of the medium.
No, but hang on...
> For each atmosphere increase in
> pressure, the volume of the water would only decrease by 46.4 parts per
> million.
True. After running some numbers and seeking the explanation for the difference
in pipe diameter, I stand mostly corrected. The numbers:
Power steering fluid is "petroleum oil." (That's what it says on the back of my
Honda PS fluid bottle.) Its compressibility is around 1.5 to 2 times that of
water, from my searching on the 'net. Power steering pump pressures max out at
between 1000 psi and 2000 psi, roughly, from my reading, with pressures being
highest when, say, one is parallel parking. The inlet pump pressure is about
atmospheric. Let's assume the PS fluid compressibility is closer to 2, because
of entrained air in the PS system. Let's assume a PS system pressure of 1000
psi. Then the % volume change from inlet to outlet is
2 * (46.4 / 1,000,000) * (1000 / 14.7) *100% = 0.63%
The outlet specific volume is thus 100% - 0.63% = 99.4% of the inlet specific
volume. This is the same as
(inlet density) / (outlet density) = 0.994
From the continuity equation for fluid flow, (mass flow in) = (mass flow out),
or
Ro1 * A1 * v1 = Ro2 * A2 * v2
where
Ro = density
A = cross-sectional area of pipe
v = fluid velocity in pipe
1 denotes inlet. 2 denotes outlet.
Assuming pipe velocities are about equal (due to material considerations), and
given that Ro1 /Ro2 = 0.994 (from above), then
A2 / A1 = 0.994
The ratio of the inlet pipe's radius to the outlet pipe's radius is the square
root of the above, or
r2 / r1 = 0.997
That's not going to be visible to the naked eye. On my 91 Civic's steering
system, I'm estimating an actual ratio of more like around 0.8 . (I am about to
start rebuilding my power steering pump and was going to give more precise
numbers, but I decided to put this off a few days.)
I am confident that the density of PS fluid at 1000 psi (or so) is used in the
outlet pipe design, but the inlet pipe design depends on other factors. Why in
particular is the inlet pipe diameter larger than the outlet pipe diameter?
Cavitation concerns.
At all times rotary pumps (as well as some other types of pumps) need to have
pressure at the pump inlet high enough so that the liquid does not vaporize.
Cavitation reduces pump efficiency, and the PS system therefore won't work as
designed. Cavitation especially tends to happen at higher pump RPMs. The fix is
to have an adequate head on the pump inlet at all times. Hence the PS reservoir
being above the pump. Hence a pipe design with minimal pressure losses. Larger
diameter piping, among other things, reduces the pressure loss.
A nice summary of cavitation appears at:
http://www.mcnallyinstitute.com/01-html/1-3.html (focuses on centrifugal pumps,
but rotary pumps, like the PS pump, also may experience cavitation)
For rotary pumps, see http://www.mcnallyinstitute.com/CDweb/r-html/r019.htm
I didn't pull these sites out of thin air, so to speak. I did forget, from years
ago, that "net positive suction head" is the driving force behind pump inlet
pipe diameter design. Only this morning after reviewing some reference books on
pump design did the bell ring.
Caroline
> BTW on your comment about never using the Kgf, it appears all the time in
> workshop manuals, even Honda ones
George, I bet these manuals are exclusively for cars whose country of design
origin is not the United States.
I don't recall seeing Kgf in my Honda's Chilton's or at the UK site's Honda
manuals. But I believe you that it does pop up. I know I haven't read as many
manuals as you and many of the regulars here.
What I do see in my Honda Chilton's and at the UK site is torques specified in
"lb-ft" and "kg-m."
As you probably know, the "lb-ft" is supposed to be lbf-ft." I imagine the kg is
supposed to be kgf, too. (Not gonna explain all the notation. People who've
worked with both American and metric know about pounds(mass) and pounds(force),
etc. They get this or they don't.)
> and you'll find Kgf/cm˛ on many pressure
> gauges in the U.S.
I certainly wouldn't bet against Kgf/cm˛ cropping up. Indeed, it's on my
rinky-dink tire air compressor in the garage right now.
But for any application in U.S. power plants, U.S. military equipment (from
ships to tanks), etc., with signficant non-vacuum pressure., I know psi is
usual. Newport News shipyard does not design using Kgf/cm˛ .
> Yes we are a backward country as far as SI units
I don't feel still using mostly English units makes the U.S. backward.
If a wannabee engineer is uncomfortable with unit conversions, he/she won't be
anymore comfortable with an "all metric" system than with an all English system,
IMO. There are just so many types of units out there. You either get used to
carrying around a little booklet of conversion factors, or you get out of the
business.
Obviously the yahoos with NASA circa 1998 spilled coffee on their conversion
booklets the day they were designing for thrust for the Mars Climate Orbiter.
They forgot to convert pounds(force) to newtons. The rest is history (crash;
millions of bucks down the drain).
> go but
> mechanics and plumbers etc. can relate to a Kg or a cm˛ - they know what it
> feels like and they like that and if they're going to be forced to metrify,
> they prefer something err, tangible.
I'm going to respectfully disagree with this. I think most U.S. mechanics and
plumbers are far more comfortable with pounds and inches, and they spend most of
their lives with these units as opposed to kilograms
> You know the chassis design specs for
> the Grandam Rolex racing series are all in inches and lbs - keeps them
> furriners away...
Ha ha ha... :-)
> and none of the suckers are going to stray off into the
> LeMans series.
> We're also not alone in bastardized systems - all the Japanese and European
> auto mfrs are now quoting engine brake power in pferdestärkes (ps) and one
> of those is exactly 75 kilogram-force meters of work per second which
> fortuitously works out to .9862bhp.
George, this little review is almost as fun as reading the white pages, but...
> So in this case, at one time, the
> metric folks bent to the ubiquity of the imperial unit based bhp and
> invented a metric measure which closely corresponded to it - ironic!
Aw, c'mon. Little gems come out of conversions all the time.
A kilowatt is very close to 3/4 of a horsepower, for example.
Anyway, I need to go study up for my brake caliper rebuild... ;-)
Pat Norton
>Obviously the yahoos with NASA circa 1998 spilled coffee
>on their conversion booklets the day they were designing
>for thrust for the Mars Climate Orbiter. They forgot to
>convert pounds(force) to newtons. The rest is history
>(crash; millions of bucks down the drain).
NASA specified and used metric units so there was no need in the
design for conversion. Unfortunately Lockheed Martin failed to follow
the specification.
The official report says:
www.hq.nasa.gov/office/codeq/risk/mco_mib_report.pdf
"the root cause for the loss of the MCO spacecraft was the failure to
use metric units... of Newton-seconds (N-s). Instead, the data was
reported in English units of pound-seconds (lbf-s). ... The SIS, which
was not followed, defines both the format and units"
Caroline
> Caroline wrote
> >Obviously the yahoos with NASA circa 1998 spilled coffee
> >on their conversion booklets the day they were designing
> >for thrust for the Mars Climate Orbiter. They forgot to
> >convert pounds(force) to newtons. The rest is history
> >(crash; millions of bucks down the drain).
>
> NASA specified and used metric units so there was no need in the
> design for conversion.
Unit conversions of one kind or another are inevitable in any large-scale
engineering project. Manufacturers, consultants, etc. may sell their product
using pounds or other English units. Should NASA not contract with such
businesses, thus reducing competition, in violation of its "Faster, Better,
Cheaper" pledge?
NASA specifying "all metric" would certainly not preclude a metric conversion
error, either.
> Unfortunately Lockheed Martin failed to follow
> the specification.
This in no way, shape, or form absolves NASA of some of the blame. Those
employed directly by NASA liaison extensively with sub-contractors. See below
for a prime example of how NASA engineers could have, and, according to the
"Mars Climate Orbiter Mishap Investigation Board," should have detected this
error.
> The official report says:
> www.hq.nasa.gov/office/codeq/risk/mco_mib_report.pdf
> "the root cause for the loss of the MCO spacecraft was the failure to
> use metric units... of Newton-seconds (N-s). Instead, the data was
> reported in English units of pound-seconds (lbf-s). ... The SIS, which
> was not followed, defines both the format and units"
It also points a heavy finger at NASA itself. For example, from the Executive
Summary, page 6:
_____
The Mars Climate Orbiter mission was conducted under NASA's "Faster, Better,
Cheaper" philosophy, developed in recent years to enhance innovation,
productivity and cost-effectiveness of America's space program. The "Faster,
Better, Cheaper" paradigm has successfully challenged project teams to infuse
new technologies and processes that allow NASA to do more with less. The success
of "Faster, Better, Cheaper" is tempered by the fact that some projects and
programs have put too much emphasis on cost and schedule reduction (the "Faster"
and "Cheaper" elements of the paradigm). At the same time, they have failed to
instill sufficient rigor in risk management throughout the mission lifecycle.
These actions have increased risk to an unacceptable level on these projects.
_____
From page 80:
_____
The Board found several instances of inadequate training in the MCO project. The
[NASA controlled, Cal Tech Jet Propulsion Laboratory www.jpl.nasa.gov]
operations navigation team had not received adequate training on the MCO
spacecraft design and its operations. Some members of the MCO team did not
recognize the purpose and the use of the ISA. The small forces software
development team needed additional training in the ground software development
process and in the use and importance of following the Mission Operations
Software Interface Specification (SIS). There was inadequate training of the MCO
team on the importance of an acceptable approach to end to end testing of the
small forces ground software. There was also inadequate training on the
recognition and treatment of mission critical small forces ground software.
____
I'm one of those former government contracted, defense industry engineers who
did not look the other way when our people did wrong. It was always embarrassing
when one met some kid engineer or some middle-aged engineer who thought it was
okay to cut corners. They are out there. This mishap is just one example of how
engineers screw up royally.
Bozo
I like your numbers, and seems we now agree.
By the way, cavitation also wears out the pump, so it's important for a
pump that runs continiously (as does the power steering pump does) to have
a good inlet flow, otherwise it will have a short life.
(It is also not very fuel efficient to have the pump running all the time,
as much of the time the power steering is not required - but it does !!!!)
Caroline
snip
> By the way, cavitation also wears out the pump, so it's important for a
> pump that runs continiously (as does the power steering pump does) to have
> a good inlet flow, otherwise it will have a short life.
Absolutely.
> (It is also not very fuel efficient to have the pump running all the time,
> as much of the time the power steering is not required - but it does !!!!)
I don't follow. When do you want the power steering off?
Only when the car is stopped at a light for a few minutes can I see maybe having
a design where the pump is not rotating (one way or another; electric or
disconnected from the crankshaft, somehow). Such a design I suppose would turn
the power steering pump off for a few minutes, while the car is idling at a
stoplight, and then, when the driver presses the gas, the PS pump would start
again.
Seems like there would be too much delay for safety.
Otherwise, I want that power steering while cruising on the highway or moving
anytime at all, for quick response; for safety.
I did read in the Usenet archives about at least one person who disconnected the
PS pump (by removing the PS belt) to gain more performance from his engine. Said
he felt the performance (hmm; I think we're talking an extra 2 hp or so, tops)
but steering was exhausting.
Interesting discussion, anyway.
Bozo
<caroline1...@earthlink.net> wrote:
>
>> (It is also not very fuel efficient to have the pump running all the
>> time,
>> as much of the time the power steering is not required - but it does
>> !!!!)
>
> I don't follow. When do you want the power steering off?
It's not required when ever it's not doing any work, for example driving
along a straight road, or even at high speeds where the steering input is
small.
Of course you want it available all the time, as you may need to make an
unexpected lane change or what ever, so it must run.
However to have a pump and accumulator and clutch would be expensive.
Another solution is electric power steering, it's more fuel efficient
(motor only runs when moving the rack) but some people do not like the
feel, and it's not cheap.
As to being able to notice a difference of a couple of horsepower, I
assume it's about the same effect as turning on or off the A/C compressor,
as that is also a couple of hp. (I'm using approximations again !!!).
Caroline
> <caroline1...@earthlink.net> wrote:
>
> >
> >> (It is also not very fuel efficient to have the pump running all the
> >> time,
> >> as much of the time the power steering is not required - but it does
> >> !!!!)
> >
> > I don't follow. When do you want the power steering off?
>
> It's not required when ever it's not doing any work, for example driving
> along a straight road, or even at high speeds where the steering input is
> small.
Okay. I see from my _Marks' Standard Handbook for Mechanical Engineers_ that
normal, straight highway driving relies on a mechanical, spring-action pre-load
mechanism (you may know more about this than I) and *no* hydraulic assistance.
This gives the driver an excellent "feel of the road." So Marks says.
> Of course you want it available all the time, as you may need to make an
> unexpected lane change or what ever, so it must run.
> However to have a pump and accumulator and clutch would be expensive.
>
> Another solution is electric power steering, it's more fuel efficient
> (motor only runs when moving the rack) but some people do not like the
> feel, and it's not cheap.
Noted.
> As to being able to notice a difference of a couple of horsepower, I
> assume it's about the same effect as turning on or off the A/C compressor,
> as that is also a couple of hp. (I'm using approximations again !!!).
:-)
So am I.
I think that 2 Hp "tops" estimate I made may be off by a factor of 10 or so for
normal driving. It's only when doing something like parallel parking that
serious power steering pump Hp is required.
Thanks for checking the calculations I made before.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
>> BTW on your comment about never using the Kgf, it appears all the time in
>> workshop manuals, even Honda ones
>
>George, I bet these manuals are exclusively for cars whose country of design
>origin is not the United States.
I'm talking about the Helm manuals which are the *only "Honda" manuals
which, AFAIK, are country agnostic though there is usually both the Kg
(usually as Kgf but not always) and the lb.
>I don't recall seeing Kgf in my Honda's Chilton's or at the UK site's Honda
>manuals. But I believe you that it does pop up. I know I haven't read as many
>manuals as you and many of the regulars here.
>
>What I do see in my Honda Chilton's and at the UK site is torques specified in
>"lb-ft" and "kg-m."
>
>As you probably know, the "lb-ft" is supposed to be lbf-ft." I imagine the kg is
>supposed to be kgf, too. (Not gonna explain all the notation. People who've
>worked with both American and metric know about pounds(mass) and pounds(force),
>etc. They get this or they don't.)
Yeah well it seems that we (my contemps and I) wasted a lot of time
learning stuff which was obsolescent: how lbf-ft was torque and ft-lbf was
work. I dunno whether to mourn the loss of the poundal or curse my science
teacher, his curriculum and the unnecessary grief it all gave us.
>> Yes we are a backward country as far as SI units
>
>I don't feel still using mostly English units makes the U.S. backward.
As far as falling into line with the rest of the world - yes... and in a
"global economy".<shrug>
>> go but
>> mechanics and plumbers etc. can relate to a Kg or a cm² - they know what it
>> feels like and they like that and if they're going to be forced to metrify,
>> they prefer something err, tangible.
>
>I'm going to respectfully disagree with this. I think most U.S. mechanics and
>plumbers are far more comfortable with pounds and inches, and they spend most of
>their lives with these units as opposed to kilograms
Oh sure but if they are to be forced to metrify.........
George Macdonald
>On Fri, 25 Jun 2004 23:12:21 GMT, Caroline
><caroline1...@earthlink.net> wrote:
>
>>
>>> (It is also not very fuel efficient to have the pump running all the
>>> time,
>>> as much of the time the power steering is not required - but it does
>>> !!!!)
>>
>> I don't follow. When do you want the power steering off?
>
>It's not required when ever it's not doing any work, for example driving
>along a straight road, or even at high speeds where the steering input is
>small.
>Of course you want it available all the time, as you may need to make an
>unexpected lane change or what ever, so it must run.
>
>However to have a pump and accumulator and clutch would be expensive.
>
>Another solution is electric power steering, it's more fuel efficient
>(motor only runs when moving the rack) but some people do not like the
>feel, and it's not cheap.
Hmm, I've wondered about the direct electric systems - haven't driven one
yet so can't comment on feel. Another system which is in some G.M. Euro
models (Vauxhall, Opel etc.) is a hydraulic system with an electric pump.
I drove a rental car with it and it felt OK but obviously I didn't "live
with it" for long.
SoCalMike
>
> I don't follow. When do you want the power steering off?
on the freeway. any speed above crawling, basically. hell, even
crawling, if its in a straight line.
ive got no PS on my 98 civic CX, and the only time i wish i had it is
during multi-point parking maneuvers. not that i need to make many,
since its got a pretty tight turning radius.
some cars are switching to an electric PS pump. makes sense, in a way.
Caroline
>
> on the freeway. any speed above crawling, basically. hell, even
> crawling, if its in a straight line.
Like I posted to Boz, I realize the hydraulics aren't needed when cruising (=
steady speed, pretty straight line driving), but one can't have this and also
the ready maneuverability, too. I'm having a hard time seeing a design where a
PS pump wasn't always running yet also ensured safety.
Maybe you guys aren't making an engineering argument but instead are "just
saying" that maybe there's a way to save some power via another PS design of
some kind?
> ive got no PS on my 98 civic CX, and the only time i wish i had it is
> during multi-point parking maneuvers. not that i need to make many,
> since its got a pretty tight turning radius.
I have driven and I think owned at least one car without PS, and yes, it's not a
big deal. Just big enough for me to make sure I always have PS in the future.
;-)
> some cars are switching to an electric PS pump. makes sense, in a way.
I don't readily see a gain in efficiency, as the electric PS pump has the
intermediary of the alternator etc. driving it, and this costs efficiency. But
maybe the electric PS pump can vary its power output in a way more appropriate
to the driving needs at the moment.
Ships use electric motors to drive their hydraulic steering fluid pumps, but
that's probably simply because it would not be practical to run the steering
pumps off the propeller shaft.
Caroline
> Yeah well it seems that we (my contemps and I) wasted a lot of time
> learning stuff which was obsolescent: how lbf-ft was torque and ft-lbf was
> work. I dunno whether to mourn the loss of the poundal or curse my science
> teacher, his curriculum and the unnecessary grief it all gave us.
Yikes to both.
I know vaguely what a "slug" is. It was still being taught in my college physics
courses, though it rarely if ever occurred in my engineering courses. I've heard
of the "poundal" (somewhere) but would have to look it up in my conversion
booklet to nail it down.
> >> go but
> >> mechanics and plumbers etc. can relate to a Kg or a cm² - they know what it
> >> feels like and they like that and if they're going to be forced to metrify,
> >> they prefer something err, tangible.
> >
> >I'm going to respectfully disagree with this. I think most U.S. mechanics and
> >plumbers are far more comfortable with pounds and inches, and they spend most
of
> >their lives with these units as opposed to kilograms
>
> Oh sure but if they are to be forced to metrify.........
True. A Kg or cm are not heard to get a handle on.
Caroline
"A pint a pound the world goes 'round."
(Speaking of rules of thumb for conversions)
Bozo
<fammacd=!SPAM^noth...@tellurian.com> wrote:
> Hmm, I've wondered about the direct electric systems - haven't driven one
> yet so can't comment on feel. Another system which is in some G.M. Euro
> models (Vauxhall, Opel etc.) is a hydraulic system with an electric pump.
> I drove a rental car with it and it felt OK but obviously I didn't "live
> with it" for long.
>
> Rgds, George Macdonald
>
The Honda 3 & 5 door Civic in Europe (USA Civics, I think are all
hydraulic systems) use an electric power steering system.
There are no hydraulics, it's basically a big electric motor directly
driving the steering rack (in parrallel with the steering wheel in case of
electrical failure). It is still an assist system, it is NOT steer by
wire.
So the motor is only powered when the rack needs to move. Most drivers
don't seem to notice the difference.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
>> Yeah well it seems that we (my contemps and I) wasted a lot of time
>> learning stuff which was obsolescent: how lbf-ft was torque and ft-lbf was
>> work. I dunno whether to mourn the loss of the poundal or curse my science
>> teacher, his curriculum and the unnecessary grief it all gave us.
>
>Yikes to both.
Yeah well it was important to remember when sweating over exams.
>I know vaguely what a "slug" is. It was still being taught in my college physics
>courses, though it rarely if ever occurred in my engineering courses. I've heard
>of the "poundal" (somewhere) but would have to look it up in my conversion
>booklet to nail it down.
A poundal was to a pound as a Newton is to a Kg. It's mentioned here
http://www.ex.ac.uk/Projects/trol/dictunit/notes3.htm#force and is included
in the conversion calculator tables.
George Macdonald
Yes I understood that and the Civic Si sold in the U.S., which is the U.K.
Type S, has the "direct" electric system. The Euro G.M. mfrs call their
system EHPS... Electro-hydraulic power-assisted steering.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"SoCalMike" <mikein562...@hotmail.com> wrote
>C wrote
>> > I don't follow. When do you want the power steering off?
>>
>> on the freeway. any speed above crawling, basically. hell, even
>> crawling, if its in a straight line.
>
>Like I posted to Boz, I realize the hydraulics aren't needed when cruising (=
>steady speed, pretty straight line driving), but one can't have this and also
>the ready maneuverability, too. I'm having a hard time seeing a design where a
>PS pump wasn't always running yet also ensured safety.
>
>Maybe you guys aren't making an engineering argument but instead are "just
>saying" that maybe there's a way to save some power via another PS design of
>some kind?
But there's not much load on the pump when it's just recirculating the
fluid anyway - some mechanical drag I suppose.
>> ive got no PS on my 98 civic CX, and the only time i wish i had it is
>> during multi-point parking maneuvers. not that i need to make many,
>> since its got a pretty tight turning radius.
>
>I have driven and I think owned at least one car without PS, and yes, it's not a
>big deal. Just big enough for me to make sure I always have PS in the future.
>;-)
>
>> some cars are switching to an electric PS pump. makes sense, in a way.
>
>I don't readily see a gain in efficiency, as the electric PS pump has the
>intermediary of the alternator etc. driving it, and this costs efficiency. But
>maybe the electric PS pump can vary its power output in a way more appropriate
>to the driving needs at the moment.
>
>Ships use electric motors to drive their hydraulic steering fluid pumps, but
>that's probably simply because it would not be practical to run the steering
>pumps off the propeller shaft.
As noted elsewhere some Euro G.M. models use this kind of system with an
electric pump. I've no idea how it works but when I drove one, a Vauxhall
Astra, I could not hear the pump switch on and off - some kind of variable
speed pump?
Caroline
> <caroline1...@earthlink.net> wrote:
> >Like I posted to Boz, I realize the hydraulics aren't needed when cruising (=
> >steady speed, pretty straight line driving), but one can't have this and also
> >the ready maneuverability, too. I'm having a hard time seeing a design where
a
> >PS pump wasn't always running yet also ensured safety.
> >
> >Maybe you guys aren't making an engineering argument but instead are "just
> >saying" that maybe there's a way to save some power via another PS design of
> >some kind?
>
> But there's not much load on the pump when it's just recirculating the
> fluid anyway - some mechanical drag I suppose.
I agree.
snip
Mike wrote
> >> some cars are switching to an electric PS pump. makes sense, in a way.
> >
> >I don't readily see a gain in efficiency, as the electric PS pump has the
> >intermediary of the alternator etc. driving it, and this costs efficiency.
But
> >maybe the electric PS pump can vary its power output in a way more
appropriate
> >to the driving needs at the moment.
> >
> >Ships use electric motors to drive their hydraulic steering fluid pumps, but
> >that's probably simply because it would not be practical to run the steering
> >pumps off the propeller shaft.
>
> As noted elsewhere some Euro G.M. models use this kind of system with an
> electric pump. I've no idea how it works but when I drove one, a Vauxhall
> Astra, I could not hear the pump switch on and off - some kind of variable
> speed pump?
I gather you mean you didn't hear the motor switch on and off. FWIW, on ships,
the RPMs of both electric motor and pump shafts stay constant. But the pump is
variable displacement, responding in proportion to where the rudder is IIRC. The
result is smooth response. The variable stroke pump used is called a "Waterbury
pump." No idea whether the Vauxhall Astra has such a pump. It's The little on
the net I see on the V Astra suggests the motor turns completely off. But this
contradicts what you think you heard.
Re the power requirements of a strictly electric-drive PS system:
After seeing Boz's post on the no hydraulic, all electric motor driven PS
system, I googled. As it turns out the claim is the all electric-driven PS
system is more fuel efficient by around 5%.
http://ca.autos.yahoo.com/030820/11/ugrz.html claims its simpler too. (And it
does sound simpler: No fluid hoses. No pump. No belt.)
A fuel savings of 5% does sound reasonable (though puny). I forgot how efficient
electric motors are. So if the PS motor is not running all the time, like Boz
and Mike suggested, yes there's a fuel savings. I suppose this all
electric-drive PS system relies heavily on electronics. I guess the parts are
probably more expensive to replace but last longer(?) and help other parts to
last longer, like a lot that's gone electronic over the decades with cars.
Graham W
"Caroline" <caroline1...@earthlink.net> wrote in message
news:b_fDc.28406$Y3.1...@newsread2.news.atl.earthlink.net...
> "SoCalMike" <mikein562...@hotmail.com> wrote
<...>
> > some cars are switching to an electric PS pump. makes sense, in a way.
>
> I don't readily see a gain in efficiency, as the electric PS pump has
the
> intermediary of the alternator etc. driving it, and this costs
efficiency. But
> maybe the electric PS pump can vary its power output in a way more
appropriate
> to the driving needs at the moment.
The advantage that the electrically driven PS has is that when there is
little or no 'assistance' required, the electric motor is under a very
light
load and, consequently, draws only a small amount of current.
Hydraulic PS pumps (correct me if I'm wrong), always deliver their rated
output volume per minute at the rated pressure whether it is going to
drive something or just dumped back into the reservoir.
> Ships use electric motors to drive their hydraulic steering fluid pumps,
but
> that's probably simply because it would not be practical to run the
steering
> pumps off the propeller shaft.
It's for the reason I gave above.
--
Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
<<snip>>
>> As noted elsewhere some Euro G.M. models use this kind of system with an
>> electric pump. I've no idea how it works but when I drove one, a Vauxhall
>> Astra, I could not hear the pump switch on and off - some kind of variable
>> speed pump?
>
>I gather you mean you didn't hear the motor switch on and off. FWIW, on ships,
>the RPMs of both electric motor and pump shafts stay constant. But the pump is
>variable displacement, responding in proportion to where the rudder is IIRC. The
>result is smooth response. The variable stroke pump used is called a "Waterbury
>pump." No idea whether the Vauxhall Astra has such a pump. It's The little on
>the net I see on the V Astra suggests the motor turns completely off. But this
>contradicts what you think you heard.
Hmmm, what I meant was that I could not hear any switch on/off of the pump
motor based on steering load but wasn't sure if that was happening or not -
it very well might if the motor could switch almost silently. I'm not sure
what's possible engineering-wise here. It was a rental car so I was not
interested in plumbing its mechanical intricacies.:-)
>Re the power requirements of a strictly electric-drive PS system:
>After seeing Boz's post on the no hydraulic, all electric motor driven PS
>system, I googled. As it turns out the claim is the all electric-driven PS
>system is more fuel efficient by around 5%.
>http://ca.autos.yahoo.com/030820/11/ugrz.html claims its simpler too. (And it
>does sound simpler: No fluid hoses. No pump. No belt.)
>
>A fuel savings of 5% does sound reasonable (though puny). I forgot how efficient
>electric motors are. So if the PS motor is not running all the time, like Boz
>and Mike suggested, yes there's a fuel savings. I suppose this all
>electric-drive PS system relies heavily on electronics. I guess the parts are
>probably more expensive to replace but last longer(?) and help other parts to
>last longer, like a lot that's gone electronic over the decades with cars.
I'm still awfully wary of EMSs.:-) It always seems to me that the more
sophisticated they make household appliance controls, the less reliable
they become... dishwashers, washing machines etc.
Caroline
C wrote
> >Re the power requirements of a strictly electric-drive PS system:
> >After seeing Boz's post on the no hydraulic, all electric motor driven PS
> >system, I googled. As it turns out the claim is the all electric-driven PS
> >system is more fuel efficient by around 5%.
> >http://ca.autos.yahoo.com/030820/11/ugrz.html claims its simpler too. (And it
> >does sound simpler: No fluid hoses. No pump. No belt.)
> >
> >A fuel savings of 5% does sound reasonable (though puny). I forgot how
efficient
> >electric motors are. So if the PS motor is not running all the time, like Boz
> >and Mike suggested, yes there's a fuel savings. I suppose this all
> >electric-drive PS system relies heavily on electronics. I guess the parts are
> >probably more expensive to replace but last longer(?) and help other parts to
> >last longer, like a lot that's gone electronic over the decades with cars.
>
> I'm still awfully wary of EMSs.:-) It always seems to me that the more
> sophisticated they make household appliance controls, the less reliable
> they become... dishwashers, washing machines etc.
While I have a less experience than you in car specifics (among other areas), I
have the same feeling about this EMS (electric motor steering?). For me, I think
it might be prejudice against change and maybe having to learn something new
(all the electronics in the EMS).
On the surface, the link above certainly seems to me to make some good points
about the simplicity of EMS vs. a hydraulic PS system.
On the third hand, I've also seen at least one media report that talks about all
the electronic gadgets in loaded, new cars and how these cars may be spending
more time in the shop, not less, compared to cars 15 years or so older.
I'm keeping an open mind on EMS and will keep studying it, especially maybe its
reliability reports in something as simple as Consumer Reports annual April car
system reliability tables.
Of course, over the last few weeks, having recently nailed down and fixed all
the itty-bitty oil leaks on my 1991 Civic LX; given its great fuel mileage; now
also having my fancy, "proven" crankshaft pulley holder toy... uh, tool; and
looking at, at worst, a new clutch in the next few years, I'm thinking the new
Toyota Echo I have been eyeing is now five years or more away. We'll see if
Toyota has EMS by then. Or maybe Honda will wise up and start making Civics with
1.5 liter engines again and EMS.
George Macdonald
<caroline1...@earthlink.net> wrote:
>"George Macdonald" <fammacd=!SPAM^noth...@tellurian.com> wrote
>C wrote
>> >Re the power requirements of a strictly electric-drive PS system:
>> >After seeing Boz's post on the no hydraulic, all electric motor driven PS
>> >system, I googled. As it turns out the claim is the all electric-driven PS
>> >system is more fuel efficient by around 5%.
>> >http://ca.autos.yahoo.com/030820/11/ugrz.html claims its simpler too. (And it
>> >does sound simpler: No fluid hoses. No pump. No belt.)
>> >
>> >A fuel savings of 5% does sound reasonable (though puny). I forgot how
>efficient
>> >electric motors are. So if the PS motor is not running all the time, like Boz
>> >and Mike suggested, yes there's a fuel savings. I suppose this all
>> >electric-drive PS system relies heavily on electronics. I guess the parts are
>> >probably more expensive to replace but last longer(?) and help other parts to
>> >last longer, like a lot that's gone electronic over the decades with cars.
>>
>> I'm still awfully wary of EMSs.:-) It always seems to me that the more
>> sophisticated they make household appliance controls, the less reliable
>> they become... dishwashers, washing machines etc.
>
>While I have a less experience than you in car specifics (among other areas), I
>have the same feeling about this EMS (electric motor steering?). For me, I think
>it might be prejudice against change and maybe having to learn something new
>(all the electronics in the EMS).
EMS (Electro-Mechanical Systems) in general - thus the reference to
dishwashers etc. The old systrems with the rotating dial worked almost
forever; the new umm "programmable" systems always seem to be failing, with
replacement of the entire control unit for ~$300. the only repair option.
>On the surface, the link above certainly seems to me to make some good points
>about the simplicity of EMS vs. a hydraulic PS system.
Yep and it would be nice when working on the car to err, lose the pulley,
hoses and belt.:-) something always seems to get in the way of something
you want to do. OTOH hydraulic systems are now well understood and last
very well with very little leakage problems.
There are some good articles on the Web, with a good illustration here
http://www.egr.msu.edu/autoweb/Class/Proj_2001/backlash/I_bginformation.htm
of Honda's EPS as used on the NSX/s2000. The biggest potential problem I
see with it is mechanical wear and lubrication to avoid it. The obvious
advantage of a hydraulic system is that the rack is pushed by a hydraulic
ram so there is very light stress on the rack & pinion and related
bushings. I can foresee, e.g. people who go to bigger wheels/tires, taking
a factory EPS beyond its design limits easily and breaking the
electro-mechanical drive.
>On the third hand, I've also seen at least one media report that talks about all
>the electronic gadgets in loaded, new cars and how these cars may be spending
>more time in the shop, not less, compared to cars 15 years or so older.
Yep and from what I gather, VW is a prime example here with all their
glitches in the electronic gadgetry in recent models. I also remember the
days when you could limp home for hours with a failed/failing alternator or
broken belt - all the battery needed to do was supply spark to the engine -
no more.:-(
Caroline
> >On the surface, the link above certainly seems to me to make some good points
> >about the simplicity of EMS vs. a hydraulic PS system.
>
> Yep and it would be nice when working on the car to err, lose the pulley,
> hoses and belt.:-) something always seems to get in the way of something
> you want to do. OTOH hydraulic systems are now well understood and last
> very well with very little leakage problems.
True, from what I've seen. I note I'm not re-building my 13+ year old power
steering pump anytime soon, after all. Seems the silly leaks were all fixed by
more basic seal replacements, like valve cover grommets (ouch). We rarely see
reports of power steering leaks here at the newsgroup, too.
> There are some good articles on the Web, with a good illustration here
> http://www.egr.msu.edu/autoweb/Class/Proj_2001/backlash/I_bginformation.htm
> of Honda's EPS as used on the NSX/s2000. The biggest potential problem I
> see with it is mechanical wear and lubrication to avoid it. The obvious
> advantage of a hydraulic system is that the rack is pushed by a hydraulic
> ram so there is very light stress on the rack & pinion and related
> bushings.
After briefly studying the drawing at the above site and considering how
power(-assisted) steering rack and pinion systems work, I agree with you. In
sum, an EMS has more mechanical gearing power transmission than a hydraulic
system. That extra mechanical gearing power transmission will require more
design "attention."
> I can foresee, e.g. people who go to bigger wheels/tires, taking
> a factory EPS beyond its design limits easily and breaking the
> electro-mechanical drive.
I am figuring the engineering design factored this in. E.g. the gears are made
of higher strength (fatigue and yield) steel than the ordinary, hydraulic PS
rack and pinion? No idea.
Time will tell, I suppose.
These net reports are certainly optimistic about the trend being towards EMS
power steering.
Maybe some manufacturer bias is more than a wee bit present.
(And a 42 volt electrical system, per the site above? I wonder if those students
aren't being a bit optimistic as they talk about "engineers" wanting to drive
the water pump and A/C compressor with electric motors. Surely this has been
considered in the past. I will have to think about why such a switch has not
been made.)
> >On the third hand, I've also seen at least one media report that talks about
all
> >the electronic gadgets in loaded, new cars and how these cars may be spending
> >more time in the shop, not less, compared to cars 15 years or so older.
>
> Yep and from what I gather, VW is a prime example here with all their
> glitches in the electronic gadgetry in recent models. I also remember the
> days when you could limp home for hours with a failed/failing alternator or
> broken belt - all the battery needed to do was supply spark to the engine -
> no more.:-(
:-)