Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: JamesV6CDX on 20 December 2007, 13:13:09
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Idle on LPG is now crap, it hunts all over the place, and stalls upon stopping. Even at full temp.
I'm driving around everywhere on petrol now.
The Evap is lovely and hot, and no obvious software issues. Please Help :'(
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Mine was not drivable until warm.
So I let it idle on gaas for about 10 minutes to thoroughly warm up.
Very cold air is denser, so try richening the mixture slightly.
What temperature is the vapour hose?
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James, could you have a blocked filter?
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Thanks for all the replies.
The hoses are all red hot, and so is the evap.
Even when fully up to temperature, it idles really rough on gas.
Through the rev range is fine... and filter is new.
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when mine forst goes over to gas it does faulter a lot for about 20-30 seconds, from there is it fine.......
i would try and richen the mix slightly, try moving the whole map up a point or two and see if that helps
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when mine forst goes over to gas it does faulter a lot for about 20-30 seconds, from there is it fine.......
i would try and richen the mix slightly, try moving the whole map up a point or two and see if that helps
Tried that, no joy ;)
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Idle on LPG is now crap, it hunts all over the place, and stalls upon stopping. Even at full temp.
I'm driving around everywhere on petrol now.
The Evap is lovely and hot, and no obvious software issues. Please Help :'(
the only reason coming to my mind is MAF. because the changing parameter can only be air in the mixture,
if one the LPG equipment parts didnt go foobar..
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Idle on LPG is now crap, it hunts all over the place, and stalls upon stopping. Even at full temp.
I'm driving around everywhere on petrol now.
The Evap is lovely and hot, and no obvious software issues. Please Help :'(
the only reason coming to my mind is MAF. because the changing parameter can only be air in the mixture,
if one the LPG equipment parts didnt go foobar..
That would also cause bad idle on petrol, though...
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old carburator systems never had problems with LPG in very cold weather (-15 Celcius ) ..I remember even the car in the morning start more easy with LPG then petrol..
As I remember we generally block the air entrance half with bandage..Can you try that ?
I think the main difference between those systems is the ECU arranging the amount of fuel injected according to air flow measured through MAF..
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Check your plugs
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i've done that as well, the plugs are new :'(
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Bigger/better evaporator?
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what effect would clamping the vac pipe have? Should I give this a go and see if idle smooths out?
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Stop it increasing output when throttle is pushed
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What is the vapour pressure doing? If that's stable I'd say the vapouriser is OK.
Can you cut individual cylinders and see if one or two are playing up or the whole lot?
Kevin
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What is the vapour pressure doing? If that's stable I'd say the vapouriser is OK.
Can you cut individual cylinders and see if one or two are playing up or the whole lot?
Kevin
That's my next plan mate. the lpg pressure is 1.5 bar which I think is OK?
I hope I don't have a duff injector or something stupid..
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Can you do an auto calibration to reset the ECU.........see if it cures it......just to check its not the dis pack :y
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Can you do an auto calibration to reset the ECU.........see if it cures it......just to check its not the dis pack :y
Done that too ;D
(Made no difference)
I'll switch injectors to gas one at a time, and see if it happens then...
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Can you do an auto calibration to reset the ECU.........see if it cures it......just to check its not the dis pack :y
Done that too ;D
(Made no difference)
I'll switch injectors to gas one at a time, and see if it happens then...
Actually dont know what i was waffling on about there..........could still be dis pack :(
Have you got a spare? to try out?
Just thinking even if you switch injectors one at a time and it occurs.....doesnt really tell you if lpg prob or ign prob :-/
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No - and I aint fitting one in this weather either!
I've just found a few fault codes I will post about shortly
I've also un-intentionally "reset" the ECU by blowing the fuse (don't ask) but it seems to idle OK tonight
I'll see what morning brings :-/
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That's my next plan mate. the lpg pressure is 1.5 bar which I think is OK?
I hope I don't have a duff injector or something stupid..
I'm just wondering if the pressure stays stable when it stumbles? If it fluctuates, it indicates a problem upstream of the injectors. If not, I'm wondering if a bit of debris has lodged in one of the nozzles / injectors?
Kevin
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I'm wondering if a bit of debris has lodged in one of the nozzles / injectors?
Kevin
I sincerely hope not...
My only thoughts about that - is that it would make the problem cylinder specific - I can't isolate it to any particular cylinder by flicking them onto petrol one by one
Also - if you just run LPG on one cylinder, and petrol on the other 5, it's fine, no matter which pot you've got injecting LPG.
So all the injectors and nozzles are doing there job :'(
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Is your evaporator clogged up with sh**e? MDTM had simular issues with his 'project lpg' estate and he flushed out the gas side of the evaporator to resolve i think...?
Mark - Can you confirm?
Also had running problems on my 2.0 LPG car, was ok on petrol but shi*e on LPG. Eventually the problem worked its way over to petrol, at which point i changed teh HT leads and - hey presto it worked!
I think LPG needs a good spark, much better than petrol anyways, so are your HT/DIS and plugs ok?
Over.
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Evap is new, and coolant system is clean
This morning it was better, but not fixed.
I noticed if I switch it onto a different make of injector in the software, it becomes much better, BUT blows the LPG fuse at high revs - so not a good idea.
TBH I'm a bit stuck
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I read somewhere that LPG was less forgiving when it comes to weak combustion, whereas petrol will happily stumble on, if you're spark is a bit weak LPG will react accordingly.
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Hi James,
Those injectors have 1 ohm coils, so 12 volts across them takes 12 amps PER injector. At full throttle all 6 will be open most of the time so this is why the fuse is blowing.
With the correct settings they are pulsed on for a short period to open them quickly and then they are current limited by PWM so they don't cook. I think you have now got a setting for a high impedance injector that doesn't require current limiting. It's lucky the fuse blew because the injectors would have been next, possibly the ECU :o
However, what you've found points to a problem with the injectors. There should be no difference in running between the settings in the software, everything will just run hotter without a current limit.
I would have a chat with Jeremy and see what he suggests, and just confirm that we had the right setting for those injectors.
Also, just double check the power connections to the LPG ECU. Just maybe it's got a bad power connection and it's struggling to run the injectors. Does the battery voltage reported by the LPG ecu look sensible under all conditions? Doesn't drop off significantly at high revs?
Kevin
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Cheers Kevin
It's consistently about 12.5 volts under all conditions...
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Just to recap:
1) LPG pressure is ok, about 1.5bar when running and pressure does not drop off when the engine falters, indicating supply is OK
2) Fuel mapping and injector timing is spot on. I’m confident all sensors are selected correctly.
3) Car is totally happy up to the red line, and I’m sure all is configured well on the software. Prob is idle only.
4) Idle is fine on petrol, but poor on gas.
5) Evaporator is clear and is getting very hot with coolant flow. Temp reported as over 50deg on software.
6) Spark plugs, and all ignition components new
7) Cylinder compressions fine
8) Lambda readings are fine, they show voltage under extreme load or revs, and cycle ok
9) No present fault codes in petrol ECU, and car is fine on petrol.
10) All connections are secure, pipework is kink free and clear of obstructions.
11) I cannot eradicate the problem by switching specific injectors to petrol only, etc…
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LPG supply up the the injectors is fine if pressure is stable so we can discount that (except that I thought it ran 1 bar pressure, not 1.5 :-/).
It's fine on Petrol so we can discount air leaks, ICV, EGR, etc.
That leaves the LPG injectors and the signals to them.
Does anything on the display of the LPG software change when the idle falters? Presumably RPM, but does it still appear to reflect the true engine RPM? LPG pressure and supply voltage have been checked and remain stable? What about the manifold pressure and LPG injector duration? Does anything go off the rails when it misbehaves?
What LPG injector duration is it running at idle?
When you switch to petrol does the LPG vapour pressure decay away or does it remain constant?
Kevin
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Actually, just thought. Can you get the screen up on the LPG software where there's an "oscilloscope" display of all the parameters, wait for it to falter and then capture the screen then post it?
Kevin
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Actually, just thought. Can you get the screen up on the LPG software where there's an "oscilloscope" display of all the parameters, wait for it to falter and then capture the screen then post it?
Kevin
I'll do it asap :y
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I have the screen dump, will post up in a mo
This problem is DEFINATELY related to the outside temperature... today it was about 6 degrees warmer, and once the engine was up to temp, it hasn't faltered once all day on gas.... whereas before it was hunting after a 50 mile run!
Is there too much cold air getting in then? Would it be too much of a bodge to "restrict" the intake a bit for the winter (or even as a test?)
**looks at the gaffa tape....**
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I have the screen dump, will post up in a mo
This problem is DEFINATELY related to the outside temperature... today it was about 6 degrees warmer, and once the engine was up to temp, it hasn't faltered once all day on gas.... whereas before it was hunting after a 50 mile run!
Is there too much cold air getting in then? Would it be too much of a bodge to "restrict" the intake a bit for the winter (or even as a test?)
**looks at the gaffa tape....**
Yes. ;) MAF is measuring the volume and temperature of air entering the engine and providing the appropriate amount of fuel. The inlet is already pretty well restricted at idle - by the throttle.
Have any of the parameters on the LPG ecu changed dramatically since it was cold?
Kevin
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None whatsoever Kevin, on the software, it's all as normal as it's ever been....
Last night I factory reset the ECU, and set it up again, inc calibration and fuelling.
It goes like something off a shovel on LPG now..
I did consider a pottential dodgey MAF (I have a MAF code 73 stored)... but I was getting this code before, and have since replaced the MAF with a known good...
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So... Air temperature seems to be an issue. In theory the inlet air temperature sensor should be compensating for this and, in addition, it should be closed loop so the lambda sensors are also correcting the mixture - assuming the sensor voltages were cycling. Vapour temperature could be another variable but I guess it doesn't lose that much heat between vapouriser and engine and, again, any discrepencies should be taken out of the equation in closed loop running. :-/
Makes me wonder if there's some grease in the injectors that's getting a bit thick in the cold and causing them to stick - but surely a good run would free them off?
I believe Jay W said he had to strip and clean one of his injectors to clear his misfire. May be worth a shot. Seems odd that a Polish LPG system has problems in the cold.
Kevin
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Maf can be (worth trying half blocking the air inlet) or
I think LPG stochiometric map cant balance very cold temperature (if its trying)
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Just wondering, to confirm it's air temperature related, can you remove the intake ducting from the bottom of the airbox and bodge something to draw warm air from behind the rad?
Kevin
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Just wondering, to confirm it's air temperature related, can you remove the intake ducting from the bottom of the airbox and bodge something to draw warm air from behind the rad?
Kevin
Not a bad idea at all.. and one I have considered.... I think it's worth a go...
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I went out from cold tonight, and it was absolutely fine, no falter whatsoever, and loads of power on gas. MID read 1.5 deg C...
As silly as this sounds, I have been using one particular gas station. I might try filling up somewhere else, just to eliminate another variable (albeit an ulikely one)
I saw a post on another forum earlier about suspect LPG from some garages.
For example, I think if Taxi Driver fills up at BP (Where I have been) His Emissions light comes on...
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Screen shot of graph, just after the blip:
(http://i89.photobucket.com/albums/k205/jamesv6cdx/blip.jpg)
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It doesn't cure your problem but mine has been a wee bit rough idling since the temp dropped <-3. Lets see if it improves with the weather!!
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COuld be butane mixed in?
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Hmm. Damn jpeg has fubar'ed the colours >:(
I think the RPM line is wandering between about 1000 and 400 RPM. Uncommanded, I take it?
LPG pressure looks stable throughout so the evaporator seems in the clear. LPG injector duration seems to follow petrol injector duration which isn't exactly stable - cause or effect? :-/
Lambda sensors are cycling, a little unstable but, again, difficult to tell if that's because the ECU is trying to adjust idle or because the fuel is all over the place.
It's really difficult to see how a few degrees of air temperature could make a difference. Correction required due to air density would easily be taken out by the Lambda correction even if the IAT wasn't doing its' job.
I'd go with the dodgy fuel theory I think.
I'd say see how it goes for a while....
Kevin
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That graph was after about 15 mins of running on a cold day, with no input from me. It was just left to it's own "idle" devices...
Funny enough, last night I put half a tank of LPG from another garage in, I wonder if this is why it feels better today...
On this basis - I guess I'm going to have to drain the tank - Go fill up at Shell, and see what happens from there!
I do still intend to monitor the fault codes on the engine ECU, and see if anything persistent comes back that could be causing the issues...
Martin, re. your butane comments - I have read that some garages put 30% butane in the mix - and this makes it more economical?
I do intend to get to the bottom of this - other than the intermittent idle on gas, this car is close to perfect..
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I think the RPM line is wandering between about 1000 and 400 RPM. Uncommanded, I take it?
Totally - this is the hunting...
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I went out from cold tonight, and it was absolutely fine, no falter whatsoever, and loads of power on gas. MID read 1.5 deg C...
As silly as this sounds, I have been using one particular gas station. I might try filling up somewhere else, just to eliminate another variable (albeit an ulikely one)
I saw a post on another forum earlier about suspect LPG from some garages.
For example, I think if Taxi Driver fills up at BP (Where I have been) His Emissions light comes on...
Yes it did......but the bulb has blown now, so I dont have that problem anymore :y ;D