Start engine on LPG not petrol?
Yvan
why is engine always started on petrol (cold and hot), and then at ~2500
rpm switched to LPG?
There is a way (ignition ON while on LPG, switch to petrol and back to
LPG, than start the engine) to start engine not on petrol but LPG, I
tested it (while engine was hot), and it works fine.
Is there any particular reason why I can not start engine on LPG by
default?
Stewart Hargrave
People quite often ask this. My system works exactly as you describe.
The only reasons for starting on petrol, it seems, are 1) when it is
very cold, there may not be enough heat in the cooling system to stop
the vaporiser from freezing a few moments after starting. 2) it's good
to keep the petrol system exercised, so that if you ever need to
switch to petrol you won't have problems with gummed up injectors or
carburettor jets.
But you have to balance this against some sound reasons for starting
on LPG. A cold engine uses petrol very inefficiently, because the
petrol does not like to vaporise until things warm up a little. LPG,
in its gaseous state, does not need to vaporise further, so your
initial startup will be more economical, cleaner and more efficient.
Also, petrol that condenses on the cylinder walls of a cold engine
will dilute the protective film of oil that lingers there - so called
'petrol wash'. This doesn't happen with gaseous LPG, so the time of
highest engine wear is improved.
Most LPG control boxes have some means of adjusting the change-over
rpm. Mine has a small hole in the back for a little screwdriver, that
adjusts a potentiometer. I turned it down to zero, which effectively
means it will start straight onto either LPG or petrol, depending
where the switch is (oddly, once the engine is running, if I switch
between fuels I still have to go through the revving proceedure). I
make the first start of the day on petrol, and within 5 seconds switch
to LPG. After that, all other starts that day are on LPG.
--
TSH
For email, replace 'SpamOnlyToHere' with my initials
Austin Shackles
enlightened us thusly:
none that I know of. I recommend on a dual fuel that you start the first
time of the day on petrol, and run it for a few minutes - I get mine to
change on the upchange from 2nd to 3rd. The main point of this is to make
sure that the petrol system works and give it a bit of exercise.
Thereafter I start it on gas.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Appearances: You don't really need make-up. Celebrate your authentic
face by frightening people in the street.
from the Little Book of Complete B***ocks by Alistair Beaton.
Yvan
| Most LPG control boxes have some means of adjusting the change-over
| rpm. Mine has a small hole in the back for a little screwdriver, that
| adjusts a potentiometer. I turned it down to zero, which effectively
| means it will start straight onto either LPG or petrol, depending
| where the switch is (oddly, once the engine is running, if I switch
| between fuels I still have to go through the revving proceedure). I
| make the first start of the day on petrol, and within 5 seconds switch
| to LPG. After that, all other starts that day are on LPG.
I wonder if you turn potentiometer to zero will you start on LPG.
If there was no reason against starting on LPG than LPG control box cold
have a three position switch 1. petrol only, 2. start on petrol - switch
to LPG, and 3. LPG only position. But they do not make it that way.
So maybe there is some reason LPG control boxes are made the way they
are?
--
___ ____
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/ / \/ /\ \ ** Registered Linux user #291606 **
/__/\____/--\__\ ** http://counter.li.org/ **
Briane Moore
cars, starting from cold will be much quicker on petrol than gas,
because petrol is injected nearly straight into the cylinders, whereas,
in my case, LPG has to be drawn along about four feet of inlet hose,
plenum chamber and inlet runners.
--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
Stewart Hargrave
>Nedavno Stewart Hargrave pise:
>
>| Most LPG control boxes have some means of adjusting the change-over
>| rpm. Mine has a small hole in the back for a little screwdriver, that
>| adjusts a potentiometer. I turned it down to zero, which effectively
>| means it will start straight onto either LPG or petrol, depending
>| where the switch is (oddly, once the engine is running, if I switch
>| between fuels I still have to go through the revving proceedure). I
>| make the first start of the day on petrol, and within 5 seconds switch
>| to LPG. After that, all other starts that day are on LPG.
>
>I wonder if you turn potentiometer to zero will you start on LPG.
It works like this on mine.
>If there was no reason against starting on LPG
See my original reply - there are circumstances when it is preferable
to start on petrol. I usually do it once a day.
> than LPG control box cold
>have a three position switch 1. petrol only, 2. start on petrol - switch
>to LPG, and 3. LPG only position.
Turning the pot. down to zero does effectively achieve this. I can
start on petrol; I can start on LPG. If I start on petrol and then
flip the switch I get the rev-to-change-over procedure.
> But they do not make it that way.
Well, not yours and mine, anyway. Maybe the newer stuff does.
Presumably those cars that run exclusively on LPG, without a petrol
system, have a different arrangement, too.
>So maybe there is some reason LPG control boxes are made the way they
>are?
Cussedness? Maybe the designers previously worked for Microsoft.
Stewart Hargrave
<br...@moooore.freeserve.co.uk> wrote:
>in my case, LPG has to be drawn along about four feet of inlet hose,
>plenum chamber and inlet runners.
Strewth, that could be one big bang ready to happen. Make sure your HT
electrics are in first class order, and you have a blowback arrestor
fitted.
Mark
> On or around Fri, 25 Feb 2005 20:39:17 +0100, Yvan <m...@privacy.net>
> enlightened us thusly:
>
>
>>I have an open loop LPG system on my Audi 100 2.3E and I was wondering
>>why is engine always started on petrol (cold and hot), and then at ~2500
>>rpm switched to LPG?
>>
>>There is a way (ignition ON while on LPG, switch to petrol and back to
>>LPG, than start the engine) to start engine not on petrol but LPG, I
>>tested it (while engine was hot), and it works fine.
>>
>>Is there any particular reason why I can not start engine on LPG by
>>default?
>
>
> none that I know of. I recommend on a dual fuel that you start the first
> time of the day on petrol, and run it for a few minutes - I get mine to
> change on the upchange from 2nd to 3rd. The main point of this is to make
> sure that the petrol system works and give it a bit of exercise.
>
>
> Thereafter I start it on gas.
I thought it was cold starting, and starting after short periods of
inactivity. i.e. on an open loop system, there's no facility to richen
the mixture slightly( is this necessary?) at startup, and it takes a few
turns to crank the gas through. This will put extra wear on the starter
motor. Anyone know if this is correct?
`Mark
Yvan
| >I wonder if you turn potentiometer to zero will you start on LPG.
|
| It works like this on mine.
I'll try that.
| >If there was no reason against starting on LPG
|
| See my original reply - there are circumstances when it is preferable
| to start on petrol. I usually do it once a day.
I thought resons other than few you mentioned. Some serious reasons,
like things will stop operating the way they are suppose to, or
something to break...
| > than LPG control box cold
| >have a three position switch 1. petrol only, 2. start on petrol -
| >switch to LPG, and 3. LPG only position.
|
| Turning the pot. down to zero does effectively achieve this. I can
| start on petrol; I can start on LPG. If I start on petrol and then
| flip the switch I get the rev-to-change-over procedure.
As I wrote I will test that, have to do some smow shaveling first :-)
| > But they do not make it that way.
|
| Well, not yours and mine, anyway. Maybe the newer stuff does.
| Presumably those cars that run exclusively on LPG, without a petrol
| system, have a different arrangement, too.
|
| >So maybe there is some reason LPG control boxes are made the way they
| >are?
|
| Cussedness? Maybe the designers previously worked for Microsoft.
:-))))))
Austin Shackles
enlightened us thusly:
>
>I thought it was cold starting, and starting after short periods of
>inactivity. i.e. on an open loop system, there's no facility to richen
>the mixture slightly( is this necessary?) at startup, and it takes a few
>turns to crank the gas through. This will put extra wear on the starter
>motor. Anyone know if this is correct?
Petrol systems are enriched for starting cold to combat the petrol
condensing out of the mixture onto the cold metal, so not necessary on gas.
I've succesfully run a gas-only one in the winter, never had problems
starting, even in moderate frost. The only thing that you really must have
is enough antifreeze, otherwise the reg. freezes before it warms up enough
to stop it freezing.
Doesn't obviously take more cranking, either. Sometimes it'll fire and die
and then fire again on a second attempt.
Stewart Hargrave
>Nedavno Stewart Hargrave pise:
>
>| >I wonder if you turn potentiometer to zero will you start on LPG.
>|
>| It works like this on mine.
>
>I'll try that.
>
>| >If there was no reason against starting on LPG
>|
>| See my original reply - there are circumstances when it is preferable
>| to start on petrol. I usually do it once a day.
>
>I thought resons other than few you mentioned. Some serious reasons,
>like things will stop operating the way they are suppose to, or
>something to break...
No. As long as the petrol system is used enough to keep it in working
order, it is generally percived as better to start on LPG if possible.
>
>| > than LPG control box cold
>| >have a three position switch 1. petrol only, 2. start on petrol -
>| >switch to LPG, and 3. LPG only position.
>|
>| Turning the pot. down to zero does effectively achieve this. I can
>| start on petrol; I can start on LPG. If I start on petrol and then
>| flip the switch I get the rev-to-change-over procedure.
>
>As I wrote I will test that, have to do some smow shaveling first :-)
Am I right in thinking you are not in the UK? If you are in a cold
climate, then you may suffer from vaporiser icing before the engine
warms up.
When LPG becomes vapour it has to absorb heat. This makes everything
around it cold, hence the need for extra heat from the cooling system.
If it freezes, it won't be able to vaporise the LPG properly.
In the UK there is usually enough heat in the cooling system, even
when it is cold, to prevent this. But see Austin's comment about
having enough anti-freeze, so that the water doesn't freeze and stop
circulating. If this happened, the vaporiser would freeze also..
Stewart Hargrave
>What's then missing is that the petrol richening device also sets a
>higher idle speed, so the engine does not idle for the first km of
>travel, this is fine as long as you expect this as you pull up to a
>junction.
Not sure what the solution is on a carb. system. On my early injection
system, I was able to patch in the fast idle device (an electrically
heated auxiliary air valve that by-passes the throttle, and closes as
it warms up) so that it works when using LPG.
Interestingly, I also had to patch in the petrol enrichment device,
(which also works by electrical heating), so that if I have to switch
to petrol when the engine is warm, it doesn't respond as if it were
still cold.
Yvan
| >I thought resons other than few you mentioned. Some serious reasons,
| >like things will stop operating the way they are suppose to, or
| >something to break...
|
| No. As long as the petrol system is used enough to keep it in working
| order, it is generally percived as better to start on LPG if possible.
Good.
| >| Turning the pot. down to zero does effectively achieve this. I can
| >| start on petrol; I can start on LPG. If I start on petrol and then
| >| flip the switch I get the rev-to-change-over procedure.
| >
| >As I wrote I will test that, have to do some smow shaveling first :-)
Snow has melted :-) I turned potentiometer down to zero, and when I
start the engine yellow LED does not flash (as it does until switched to
LPG), but is constantly on (meaning I am running on LPG).
But I can not be sure that no petrol is used during the engine start
process. It only looks that it's LPG only.
| Am I right in thinking you are not in the UK?
What gave me away? My grammer right? :-)
| If you are in a cold climate, then you may suffer from vaporiser
| icing before the engine warms up.
|
| When LPG becomes vapour it has to absorb heat. This makes everything
| around it cold, hence the need for extra heat from the cooling system.
| If it freezes, it won't be able to vaporise the LPG properly.
|
| In the UK there is usually enough heat in the cooling system, even
| when it is cold, to prevent this. But see Austin's comment about
| having enough anti-freeze, so that the water doesn't freeze and stop
| circulating. If this happened, the vaporiser would freeze also..
I knew that, I will take care not to start (first time of the day) on
LPG when very cold. What would be critical temperature with average
content of anti-freeze (40% where I am protecting up to ~ -30 deg.
Celsius) for starting on LPG without worrying about vaporizer freezing
up?
Stewart Hargrave
>But I can not be sure that no petrol is used during the engine start
>process. It only looks that it's LPG only.
A properly installed system should provide LPG *or* petrol, but not
both.
I guess you could disconnect the vaporiser solenoid (it will probably
be on top of your vap. with a couple of wires to it). If the car then
fails to start, you must be switched to LPG only.
>
>| Am I right in thinking you are not in the UK?
>
>What gave me away? My grammer right? :-)
Mainly because I've no idea what "Nedavno Stewart Hargrave pise"
means. Or even what language it is. Shame on me.
>What would be critical temperature with average
>content of anti-freeze (40% where I am protecting up to ~ -30 deg.
>Celsius) for starting on LPG without worrying about vaporizer freezing
>up?
No idea. Try it at normal concentration, and if the engine stalls
shortly after starting, add some more antifreeze. -30 sounds extremely
cold to me, and may, in fact, compromise cold starting with any amount
of antifreeze.
Yvan
| >| Am I right in thinking you are not in the UK?
| >
| >What gave me away? My grammer right? :-)
|
| Mainly because I've no idea what "Nedavno Stewart Hargrave pise"
| means. Or even what language it is. Shame on me.
It means something like "Not long ago Stewart Hargrave wrote". And I am
from Serbia & Montenegro (former Yugoslavia). Not a language well known
outside borders of former Yugoslavia.
| >What would be critical temperature with average
| >content of anti-freeze (40% where I am protecting up to ~ -30 deg.
| >Celsius) for starting on LPG without worrying about vaporizer
| >freezing up?
|
| No idea. Try it at normal concentration, and if the engine stalls
| shortly after starting, add some more antifreeze. -30 sounds extremely
| cold to me, and may, in fact, compromise cold starting with any amount
| of antifreeze.
Well we do not often have temperatures below -15 deg Celsius. Most of
the winter it never goes below -10 deg during night.
I tested LPG only start this morning (it was -8 deg) and my Audi started
fine. Drove away no problem.
If only I could solve my idle problem (stalling)...
Peter
> cold have a three position switch 1. petrol only, 2. start on petrol
> - switch to LPG, and 3. LPG only position. But they do not make it
> that way.
Of course they do. My BRC Just Light has a switch just like that.
Peter
Mark
> On or around Sun, 27 Feb 2005 01:58:34 +0000, Mark <m...@privacy.net>
> enlightened us thusly:
>
>
>>I thought it was cold starting, and starting after short periods of
>>inactivity. i.e. on an open loop system, there's no facility to richen
>>the mixture slightly( is this necessary?) at startup, and it takes a few
>>turns to crank the gas through. This will put extra wear on the starter
>>motor. Anyone know if this is correct?
>
>
> Petrol systems are enriched for starting cold to combat the petrol
> condensing out of the mixture onto the cold metal, so not necessary on gas.
> I've succesfully run a gas-only one in the winter, never had problems
> starting, even in moderate frost. The only thing that you really must have
> is enough antifreeze, otherwise the reg. freezes before it warms up enough
> to stop it freezing.
>
> Doesn't obviously take more cranking, either. Sometimes it'll fire and die
> and then fire again on a second attempt.
system needing tlc. I've already reoplaced the alt/coil/dizzie and
leads, about 2 years ago, so I'm thinking about a new set of leads and
plugs. I fancy magnecor leads, but I'm not sure if the benefits are
worth the outlay, and the only way to find out is to get the wallet
out....bugger. I'm also starting to think about the whole 'spark' thing
a bit more, with a view to deciding if an ignition amp is a good idea,
or whether to just buy nology leads in the first place....too many
choices for my frazzled brain. I can hear the brandy calling...
`Mark
Austin Shackles
enlightened us thusly:
> about 2 years ago, so I'm thinking about a new set of leads and
>plugs. I fancy magnecor leads, but I'm not sure if the benefits are
>worth the outlay, and the only way to find out is to get the wallet
>out....bugger. I'm also starting to think about the whole 'spark' thing
>a bit more, with a view to deciding if an ignition amp is a good idea,
>or whether to just buy nology leads in the first place....too many
>choices for my frazzled brain. I can hear the brandy calling...
I bought a set of champion triple-silicone, which were OK but nothing
special. Having invested in a set of "blue" magnecors, they are very nicely
made.
I suspect mine needs the plug gapping or replacing, every now and then it
fires up on about 5 or 6 for the first few seconds.
--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!
Mark
> On or around Wed, 02 Mar 2005 21:12:21 +0000, Mark <m...@privacy.net>
> enlightened us thusly:
>
>
>>about 2 years ago, so I'm thinking about a new set of leads and
>>plugs. I fancy magnecor leads, but I'm not sure if the benefits are
>>worth the outlay, and the only way to find out is to get the wallet
>>out....bugger. I'm also starting to think about the whole 'spark' thing
>>a bit more, with a view to deciding if an ignition amp is a good idea,
>>or whether to just buy nology leads in the first place....too many
>>choices for my frazzled brain. I can hear the brandy calling...
>
>
> I bought a set of champion triple-silicone, which were OK but nothing
> special. Having invested in a set of "blue" magnecors, they are very nicely
> made.
>
> I suspect mine needs the plug gapping or replacing, every now and then it
> fires up on about 5 or 6 for the first few seconds.
>
ignition fun :0) I had Lucas leads on, and they're a bit crap as well,
have to be real careful to stop them snapping at the connector, very
brittle for a standard lead.
`Mark