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Omega Help Area => Omega General Help => Topic started by: tgm147 on 05 March 2012, 21:55:03

Title: B****** LPG!
Post by: tgm147 on 05 March 2012, 21:55:03
Getting close to torching it again!

It has now decided it doesn't want to behave on gas. It feels very down on power, almost splutters and eventually dies off completely to a really rough idle and won't maintain any form of speed. On petrol it's fine and pulls clean all the way to the redline. This has come on very quickly today, yesterday it was perfectly fine with no troubles at all. I'm at a loss now as to what it can be. In the last few weeks she's had:

Head skim and gasket.
New GM coilpack.
New GM cam sensor.
New GM thermostat.
New NGK spark plugs.

They all cover everything I can think of that would cause this.

Any ideas guys? Want to burn the oppsing thing.
Title: Re: B****** LPG!
Post by: JamesV6CDX on 05 March 2012, 21:56:29
What LPG system?

Any warning lights?

Any fault codes in any of the ECUs? (petrol and gas)

If you need help with my last question, we can direct you to code reading methods :y
Title: Re: B****** LPG!
Post by: tgm147 on 05 March 2012, 21:58:38
Prinns VSi.
The EML is on and i'll plug it into the code reader tomorrow. I'm guessing it's going to be lean/rich exhaust and missfires on cylinders. Nothing abnormal on the LPG panel. Not going back to petrol on its own and no other lights on apart from the gas level gauge.
Title: Re: B****** LPG!
Post by: Entwood on 05 March 2012, 21:58:46
Getting close to torching it again!

It has now decided it doesn't want to behave on gas. It feels very down on power, almost splutters and eventually dies off completely to a really rough idle and won't maintain any form of speed. On petrol it's fine and pulls clean all the way to the redline. This has come on very quickly today, yesterday it was perfectly fine with no troubles at all. I'm at a loss now as to what it can be. In the last few weeks she's had:

Head skim and gasket.
New GM coilpack.
New GM cam sensor.
New GM thermostat.
New NGK spark plugs.

They all cover everything I can think of that would cause this.

Any ideas guys? Want to burn the oppsing thing.

Drive it until it starts coughing on LPG, then feel the vapouriser ??? if it is NOT hot then that might be the problem, as the liquid gas needs heat to vapourise ....
Title: Re: B****** LPG!
Post by: tgm147 on 05 March 2012, 22:00:58
Getting close to torching it again!

It has now decided it doesn't want to behave on gas. It feels very down on power, almost splutters and eventually dies off completely to a really rough idle and won't maintain any form of speed. On petrol it's fine and pulls clean all the way to the redline. This has come on very quickly today, yesterday it was perfectly fine with no troubles at all. I'm at a loss now as to what it can be. In the last few weeks she's had:

Head skim and gasket.
New GM coilpack.
New GM cam sensor.
New GM thermostat.
New NGK spark plugs.

They all cover everything I can think of that would cause this.

Any ideas guys? Want to burn the oppsing thing.

Drive it until it starts coughing on LPG, then feel the vapouriser ??? if it is NOT hot then that might be the problem, as the liquid gas needs heat to vapourise ....

Will do. Believe the vapouriser is under the header tank but will follow the pipes and have a feel around tomorrow.
Title: Re: B****** LPG!
Post by: Lazydocker on 05 March 2012, 23:53:49
Agreed... Classic symptoms of vap freezing ;) And with that list of work there's a fair chance the coolant flow to it has been fiddled/airlocked
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 12:53:22
Update time. The vapouriser is hot after a short run so I doubt its the problem. I have noticed a new noise though. Sounds like a pssh psssh psssh sound when under hard acceleration on gas but I can't smell anything.  ???
Title: Re: B****** LPG!
Post by: Lazydocker on 06 March 2012, 14:25:16
Hmm... Completely clutching at straws but could be a vac pipe issue :-\

If you've had the work done at a garage and it was fine before it went in (other issues aside) then take it back and get them to fix it FOC ::)
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 14:45:17
Hmm... Completely clutching at straws but could be a vac pipe issue :-\

If you've had the work done at a garage and it was fine before it went in (other issues aside) then take it back and get them to fix it FOC ::)

The head gasket was done by a garage but that was getting on for over a month ago and it's been perfectly fine since, just started playing up yesterday. I really am at a loss with this, been out and had it in bits as much as I can and can't see anything wrong, nothing lose or any weird bits of wiring. I've booked it into a LPG specialist next week and they're going to look over it because they install the Prins kits. With any luck it'll be a blocked filter or something simple like that. I've been through the rather big receipt book and can't find anything about the gas system being serviced, and it was installed over 70,000 miles ago.
Title: Re: B****** LPG!
Post by: Kevin Wood on 06 March 2012, 14:53:58
Update time. The vapouriser is hot after a short run so I doubt its the problem. I have noticed a new noise though. Sounds like a pssh psssh psssh sound when under hard acceleration on gas but I can't smell anything.  ???

Is the tank getting cold and sweating / icing up?
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 15:02:03
Update time. The vapouriser is hot after a short run so I doubt its the problem. I have noticed a new noise though. Sounds like a pssh psssh psssh sound when under hard acceleration on gas but I can't smell anything.  ???

Is the tank getting cold and sweating / icing up?

I haven't noticed but I'll go start it up and knock it onto gas and leave it to tick over for a while and report back.
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 15:18:06
Just done a video of the car ticking over. It seems fine but there's a definite cough when revved. It only seems worse when under load, like it can't get enough gas through.

http://youtu.be/T2ST42t3UK8

The gas tank just felt normal, not oddly cold or anything out of the ordinary.
Title: Re: B****** LPG!
Post by: Kevin Wood on 06 March 2012, 15:36:51
Update time. The vapouriser is hot after a short run so I doubt its the problem. I have noticed a new noise though. Sounds like a pssh psssh psssh sound when under hard acceleration on gas but I can't smell anything.  ???

Is the tank getting cold and sweating / icing up?

I haven't noticed but I'll go start it up and knock it onto gas and leave it to tick over for a while and report back.

You need to be pulling some serious gas out of it to notice, just thinking if it's drawing up vapour instead of liquid, as you drive the tank gets colder until it can't cope with the demand.

Given that work has been carried out on the front end, I'd say a problem with the tank is unlikely, but worth checking next time it's been on a longish run on LPG.
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 15:39:59
Update time. The vapouriser is hot after a short run so I doubt its the problem. I have noticed a new noise though. Sounds like a pssh psssh psssh sound when under hard acceleration on gas but I can't smell anything.  ???

Is the tank getting cold and sweating / icing up?

I haven't noticed but I'll go start it up and knock it onto gas and leave it to tick over for a while and report back.

You need to be pulling some serious gas out of it to notice, just thinking if it's drawing up vapour instead of liquid, as you drive the tank gets colder until it can't cope with the demand.

Given that work has been carried out on the front end, I'd say a problem with the tank is unlikely, but worth checking next time it's been on a longish run on LPG.

That'll stump that one then, it won't run for long enough on LPG to do a run. :( I'm talking it packs up within a few seconds of switching from petrol.
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 16:29:55
gone to pick a mate up from work, driven on petrol. The car is coughing a bit. Not ticking over smooth. Possible vacuum issue? Can feel the car shake and jolt. Normally dead smooth.
Title: Re: B****** LPG!
Post by: Kevin Wood on 06 March 2012, 16:42:00
I would run it on petrol only for a week, and see if it recovers and runs OK.

Possibly the fuel trims have drifted out due to an LPG problem. Running on petrol will eliminate that and it should revert to running fine.

Once we have a baseline that it's running perfectly on petrol we can take another look at the LPG issue.
Title: Re: B****** LPG!
Post by: mark.adams on 06 March 2012, 19:05:59
Any smell from the exhaust, eggy smell from the cat?
Thinking maybe under or over fuelling...
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 20:07:30
Smells a bit rich when it's just started but ticking over when it's warm it smells just like normal really.
Title: Re: B****** LPG!
Post by: Entwood on 06 March 2012, 20:10:41
gone to pick a mate up from work, driven on petrol. The car is coughing a bit. Not ticking over smooth. Possible vacuum issue? Can feel the car shake and jolt. Normally dead smooth.

I know your first post shows you have changed a few bits .. but that reads like an electrical (HT) misfire to me.... and if it is misfireing (HT wise) under petrol it will not run well under LPG.

LPG is "harder" to ignite than petrol, so the HT/spark side of the engine must in in A1 condition... if its rough under petrol .. not a chance under LPG ..  :(
Title: Re: B****** LPG!
Post by: tgm147 on 06 March 2012, 21:43:15
Going to try some new spark plugs. The guy that owned it before me said it never liked NGK plugs and would much them in weeks on gas. Going to get some from Vauxhall on Thursday.