1996 F-150 (5.8L) rough idle solved, but have question
Mr Wizzard
my 1996 F-150 w/ 5.8L (351 w) for months now, and
I set out to "shotgun" the sumbitch until I found/fixed it.
Armed with the Internet, and a pocket full of loot, I was
lucky enough to discover a brand new Ford dealership
just down the street from me (partially what inspired this
project since daily trips to the new dealership now possible).
(Truck is a 96 4x4 auto, short box, w/ 150K miles on it.)
Did all the standard stuff, 2 sets of new plug wires (yes,
learned about the aftermarket wires vs. factory ones),
cap/plugs (dealer issue), fuel filter, fuel pressure regulator,
EGR test, retest, and tripple test, vacuum leak test, yada..
Then recently ran into a slew of threads about cleaning
the air valve/throttle body plates, and thought, humm,
now *thats* really "out there". Being very mechanically
inclined and engine savy, I couldn't see this idea having
any merit. However, I did give in, and did a quick clean
of the plates from the ourside (without taking it apart).
Nada. Few more weeks go by, and I decided to dive
in once again. Started by changing the water pump.
Related? no, hell no. But I had a brand new Ford issue
water pump on the shelf that I bough 4 years ago because
I had a slight leak. But I was really after the timing chain
figuring that after 150K miles, it might be loose as a
rubber band, and since the water pump needed replaced...
Anyway, timing chain/water pump replaced, and so you
know, I'm here to tell you, that at 150K miles on this
1996 5.8L: (351w), the timing chain was NOT worth
tearing the front of the engine off for - it was hard to
tell the difference in play from the new chain to the old,
and I even changed the gears. Oh well, its done.
Struggling with the possible idea that the injectors
were to blame, and at $100/injector, I set out to
test each one. I made a testing jig. A 1-foot piece
of regular 1/2 inch copper plumbing pipe, and some
fittings. Turns out that the inside bore of regular
1/2 inch household copper plumbing pipe is the
same bore of the fuel rail. I made an inside champhor
with a plumbers tool as to not hurt the O-ring. On the
other end, got a 1/2 inch copper pipe to 3/4inch pipe
thread (female). Then a iron 3/4 inch NPT to 3/8 inch
female. Took the fitting off of air tool, and screwed
it in the end of the pipe. Lube the O-ring of an injector,
carefully slide the injector in the open end with the
champhor, fill the pipe half way up with Gumout with
the supplied straw thru the air tool fitting, then HOLD
on to the pipe, and the injector, and with your third
hand, and grab a set of test leads and hook to a
12-volt power supply (or battery). Set compressor
to about 40-50PSI. All my injectors were just fine!
sprayed out 4 nice little streams, so I put them back in.
So, back to this throttle plate cleaning business.
With the upper manifold off (need to remove it
to access the injectors on the right bank), I had
the throttle body assembly off. geSUS! was the
black gunk thick on the back of the air valve plates!
MygoodNESS, I had no idea!. Further, the first
few inches inside the upper manifold was juat as
bad (if not worse). Oh boy... another trip to the
parts store, few more cans of Gumout (now with
25%more per can!-wahoo!). Go out back, grab
that old cat litter pan (sorry Fluff), and grab that
parts brush, and get ready to get high as a kite,
and then the killer headache from hell from fumes.
About an hours worth of work, got the throttle
body cleaned, and scraped out the first 6 inches
of the inside of the upper manifold, and sprayed,
brushed, wiped the shit out of the inside of the
2 big bores in the upper manifold. Knew about
the Ford "special coating" on the plates/bore, but
oh well, "special coating" is now floating in
Fluffy's cat litter pan along with a 3 inch slury
of black gunk. Blew the shit of out it with the
compressor trying to get the Gumout out of the
rubber sealed bearing on the shaft next to the
Throttle Position Sensor. (Sensor was removed,
new one in box on bench waiting to be replaced.)
Putting it all back together was a pain. Also watch
that graphite coated gasket for hte EGR valve, I
managed to let it slip during installation and missed
a bolt hole the first go-arond. Start it up, and see
what happens. Starts ok (still seemed to have that
hesitation/occassional popping under super-sudden
wide open throttle. Oh well, will deal with later.
Engine running, check for leaks, nope, all looks good.
On fast idle, thats Ok. Few seconds, and good,
I hear it ease on down to normal idle. Playing
around a little (engine warm/hot by now) I discovered
some seeming "new" problem. When I tap the gas,
it runs up to fast idle (1,100 - 1,200 RPM) for about
8 seconds, then eases down to normal idle of 700-800.
Dang, I don't remember it doing that. Played and played
until it was at full operating temp, and it *still* does this.
Tap the accelerator, and it rund up to fast idle for 8 sec,
then comes down. How irrating. Play some more:
try to put it in gear real fast during this fast idle run-up,
and back to neutral. Interesting, dropping it into
drive (from neutral) and then back to neutral (within
that 8 seconds) seems to cancel this. Humm.
I go out to the engine, with small screwdriver (to
quickly release the latch for the connector on the
Idle Speed Control valve (man I wish that stupid
snap thing would just break off already). Reach up
in the plastic covered throttle lever area, bump the
throttle, it goes into this 8-second fast idle mode,
and quickly I unsnap the connector on the idle speed
control valve, but I can't "quite" tell if it affects it
or not. So I left it unconnected and bumped the
throttle. Ah ha! - speed comes *right* back down.
Confirmed this over and over again. So the ECU
must be doing this, and/or the valve might be bad,
or slow, or I hurt it with all that gumout/brushing.
So whats the Dealy-O ? Its been so long since I
bought this truck brnd new, I don't remember if
this is normal or not. (I *do* know that it did
the fast idle when cold, but just not after hot). BTW,
I also replaced the temp sensor (for the ECU) near
the water outlet. (2-prong job, ECU related, not the
one threaded prong for the temp gague.
So anyone with a properly *working* 1996 F-150
auto w/ 5.8L know if this "tap throttle, and it runs up
to fast idle for 8 seconds, and then back down again"
problem ?? Seems ok on the road - and a lot smoother,
and I'd have to say that the infamous "rough idle" is gone.
However, I'm also hyper sensitive to it now, so sometimes
its hard to detect if its gone or not, but I believe it is. But
I am concerned above this new condition above, and
would like to compare notes with other such owners.
I'm not overly worried since it does come back down
to normal idle, but its after 8 seconds, like clockwork.
Thanks!
Joe
vacuum leak (the usual one), and found that my truck had to get up its nerve
to try to idle down. It doesn't do that any more. So I think it's just
trying to relearn.
"Mr Wizzard" <w...@muffy-mail.com> wrote in message
news:6aidnZ2dnZ0kKGDInZ2dn...@comcast.com...
Mr Wizzard
"Joe" <J...@dontspam.net> wrote in message
news:q0rTe.5728$tc7....@fe03.lga...
> As you've detected, the computer is doing that. I recently fixed a huge
> vacuum leak (the usual one), and found that my truck had to get up its
nerve
> to try to idle down. It doesn't do that any more. So I think it's just
> trying to relearn.
Well, today was my first day back to work after
the long weekend (of repairs etc), so here's the
status: commute to work is 30 miles, of bumber
to bumper for first 9-10 miles, long/fast freeway
run of at least 12-15 miles, then the rest in more
bumper to bumber, so it got a real workout today.
Report: I now notice "three" distinct modes. In
the morning, cold, it *really* races up for cold idle
(like around 1,800 RPM), then down to this second
teir 1,100 RPM, then down to the normal 750 or so.
When warm, no 1,800, just that 1,100 every time
I tap the gas (in park/neutral), so nothings changed.
So I'm looking to compare notes with others with
a 5.8L in a 1996(-ish) F-150 w/ automatic to see
if they too have this "run up to 1,100 RPM for 8 Sec
after taping the throttle" condition. Anyone ?
Thanks!
floyd...@floydthebarber.com
you spoke of .. please?
MGP
guerra....@gmail.com
pyotr filipivich
typed in alt.trucks.ford the following:
>> >> So anyone with a properly *working* 1996 F-150
>> >> auto w/ 5.8L know if this "tap throttle, and it runs up
>> >> to fast idle for 8 seconds, and then back down again"
>> >> problem ?? Seems ok on the road - and a lot smoother,
>> >> and I'd have to say that the infamous "rough idle" is gone.
>> >> However, I'm also hyper sensitive to it now, so sometimes
>> >> its hard to detect if its gone or not, but I believe it is. But
>> >> I am concerned above this new condition above, and
>> >> would like to compare notes with other such owners.
>> >> I'm not overly worried since it does come back down
>> >> to normal idle, but its after 8 seconds, like clockwork.
>> >>
>> >> Thanks!
>> >>
>> >>
>> >>
>> >Don't know if anybody is still viewing this post, but I've been having similar problems on my 1996 f150. The idle rpm is about 1200, I rev it for a few min., drops down to about 650-750. runs pretty well after that until recently. I can drive about 25 miles to Lubbock, but I need to stop after half a mile, park it, then I can continue on the rest of the way just fine. I actually get pretty good mileage when it's running right. I'm gonna look into the vacuum lines in the morning. hopefully that's the culprit.
to run into a store.) I got real good at priming the carb in an
intersection.
Then I found out the fuel pump had a leak in the diaphragm.
Replace fuel pump and it was "right as rain." as the saying goes.
--
pyotr filipivich
The fears of one class of men are not the measure of the rights of another.
-- George Bancroft
desert...@gmail.com
1995 f150 5.8L
I was dealing with this issue for YEARS. While solving another problem I found a broken vacuum line (going into EGR solenoid) and a cracked EGR tube. After fixing those, I have not had the idle run up since then!!!
