Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: albitz on 16 April 2013, 12:26:14

Title: Misfire on LPG
Post by: albitz on 16 April 2013, 12:26:14
Had this misfire in gas for quite a while now (car runs fine on petrol).This would indicate a weakness in the HT circuit afaik so I changed the dispack a while back for one that was thought to be ok and certainly looked fine.When I took my old one out it was split and rusted so I was confident that was the problem.When I installed the replacement dispack the misfire was still there.
Yesterday I fitted another dispack which Im assured is a good one,and visably is in good condition. but the misfire is exactly the same.I was temped to change the HT leads at the same time,but didnt beause if the misfire had been cured I would have been curious if the problem had been the dispack or the leads. I guess the next step is to change the HT leads. I have a spare set which came off a car which was running fine,although that was just on petrol.
Question is,if I change the leads and the misfire is still present,what do I do next ?
I probably wont have a chance to investigate any further for several days as Im back at work from tonight,but its going to be bugging me in the meantime.
Tia for any suggestions. :y
Title: Re: Misfire on LPG
Post by: Kevin Wood on 16 April 2013, 12:29:27
Have you got a blocked LPG injector perhaps? Or injector pipe crushed / split?

Do you have the diag software for the LPG kit? If so, switch injectors back to petrol until you find the one that's misfiring then you have a clue as to where the problem is.
Title: Re: Misfire on LPG
Post by: albitz on 16 April 2013, 13:18:35
Have you got a blocked LPG injector perhaps? Or injector pipe crushed / split?

Do you have the diag software for the LPG kit? If so, switch injectors back to petrol until you find the one that's misfiring then you have a clue as to where the problem is.

Pipes look ok,reasonably sure none are kinked or crushed (had that one before),didnt check injectors tbh.I do have the software and interface but it doesnt seem to work now.Plug it into laptop and the blue light flashes once (iirc) and then nothing happens.
It was very useful for diagnosing problem last time I had trouble.I actually used it every time I drove the car to switch the relevant cylinder to petrol,until I discovered the crushed pipe.May have to replace it to try to solve this problem,if changing HT leads doesnt solve it.
Title: Re: Misfire on LPG
Post by: tunnie on 16 April 2013, 15:29:15
How old are the plugs? As we know LPG needs a stronger spark....
Title: Re: Misfire on LPG
Post by: tigers_gonads on 16 April 2013, 15:54:27
Best to change your plugs first Albs  ;)
Cheapest and easiest option.
Use the old twin electrode ones for lpg.
More open flame front so better imo
Title: Re: Misfire on LPG
Post by: albitz on 16 April 2013, 17:13:02
Should have mentioned - new GM twins a couple of thousand miles ago. :y
Title: Re: Misfire on LPG
Post by: cem_devecioglu on 16 April 2013, 18:56:31
dont know what brand you use for lpg set but nowadays there are many faulty lpg injectors around..  you may need another known working one to try..
Title: Re: Misfire on LPG
Post by: symes on 17 April 2013, 18:36:20
have you fitted new inline lpg filter to injectors?could be gunked up-heavy ends?-only a guess though
Title: Re: Misfire on LPG
Post by: albitz on 17 April 2013, 18:37:40
New filter approx 10,000 miles ago. :y
Title: Re: Misfire on LPG
Post by: symes on 17 April 2013, 18:39:50
undo it and spray some carb cleaner into it + start it and rev it-that should clear it-did on mine ;)
Title: Re: Misfire on LPG
Post by: albitz on 20 April 2013, 15:39:04
Update.
Changed HT leads today.Removed each LPG pipe(from solenoid to injectors) in turn and blew down them and resistance (or lack of it) seemed the same on all six,so assuming no blockage at injectors.Misfire just the same as it was. :'(
Dont know where to go from here,apart from get hold of a working Stag interface and see if that throws anything up. :-\
Title: Re: Misfire on LPG
Post by: albitz on 20 April 2013, 18:13:03
Dug out my interface and tried it,but it wont work.Lights flash until its plugged into laptop usb port and then they stop."no connection" message appears onscreen. So,Im stuck. :(
Title: Re: Misfire on LPG
Post by: RobG on 20 April 2013, 21:38:47
Dug out my interface and tried it,but it wont work.Lights flash until its plugged into laptop usb port and then they stop."no connection" message appears onscreen. So,Im stuck. :(
Can`t you get a replacement :-\
Title: Re: Misfire on LPG
Post by: albitz on 20 April 2013, 22:04:44
I might have to,but at around £30 I would rather avoid it if possible.Particularily as Ive only used this one a few times and the damn thing stopped working after a few months. :(
Title: Re: Misfire on LPG
Post by: albitz on 21 April 2013, 10:23:30
Or could it be that the software I have installed is out of date and needs updating ? Havent a clue tbh. :-\
Title: Re: Misfire on LPG
Post by: cem_devecioglu on 21 April 2013, 10:32:02
Or could it be that the software I have installed is out of date and needs updating ? Havent a clue tbh. :-\

sorry (as I'm a bit far to subject)  what software did you install and did anything change after software install ?
Title: Re: Misfire on LPG
Post by: cem_devecioglu on 21 April 2013, 10:39:09
Albitz, if you ask my opinion shortest route to solution is bring the car to another member who have a similiar lpg kit and try swapping injectors and some other bits :-\
Title: Re: Misfire on LPG
Post by: zirk on 21 April 2013, 10:45:32
Slightly a different angle here Albs, is the water temp, flow, vaporizer temp doing its bit? that can cause random miss fire and miss fire codes to pop up.
Title: Re: Misfire on LPG
Post by: albitz on 21 April 2013, 10:50:20
May not need to go that far Cem.I think I need to get the interface issue sorted.Then I can plug in the laptop and may well be able to see if anything is wrong on the LPG side of things or if I still need to go back to the HT circuit.
Just need to establis if it could be an update issue or similar before going down the route of acquiring a new interface. :y

Not certain tbh Chris.When I first got the car the LPG/coolant plumbing had been installed badly and it kept switching over to petrol,but didnt misfire.Replumbed it properly and it was fine after that until this misfire appeared.Its very much like a classic dispack breaking down,but Ive changed it twice now (along with HT leads)and nothing has changed.
Title: Re: Misfire on LPG
Post by: cem_devecioglu on 21 April 2013, 10:53:24
May not need to go that far Cem.I think I need to get the interface issue sorted.Then I can plug in the laptop and may well be able to see if anything is wrong on the LPG side of things or if I still need to go back to the HT circuit.
Just need to establis if it could be an update issue or similar before going down the route of acquiring a new interface. :y

Not certain tbh Chris.When I first got the car the LPG/coolant plumbing had been installed badly and it kept switching over to petrol,but didnt misfire.Replumbed it properly and it was fine after that until this misfire appeared.Its very much like a classic dispack breaking down,but Ive changed it twice now (along with HT leads)and nothing has changed.

than please check the connectors/sockets to injectors and also other related stuff.. it may be an electrical problem :-\
 
and is the battery+earth  in good nick
Title: Re: Misfire on LPG
Post by: albitz on 21 April 2013, 10:59:55
Connectors appear good,and injector solenoids all sound as though they are working ok as far as I can tell. Battery/earth fine. :y
Title: Re: Misfire on LPG
Post by: Taxi_Driver on 21 April 2013, 11:00:11
I went through a similar problem with a lpg vectra, it was missing on lpg. I tried a couple of coilpacks bought from scrap yards....in the end i stumped up about £120 for a new one from vx.....it cured the missfire.....not saying it would fix your problem......but beware some 2nd hand coil/dis packs work fine for petrol but dont quite give enough of a spark for lpg.
Title: Re: Misfire on LPG
Post by: albitz on 21 April 2013, 11:03:26
That is in the back of my mind tbh,but Im trying to avoid buying a brand new genuine dispack just for elemination purposes.
Any used dispack could present that problem unless it came from a car with LPG installed and was from someone completely trustworthy,so its a bit of a dilemna. My thinking is to persue least expensive options first. :y
Title: Re: Misfire on LPG
Post by: Taxi_Driver on 21 April 2013, 11:13:04
That is in the back of my mind tbh,but Im trying to avoid buying a brand new genuine dispack just for elemination purposes.
Any used dispack could present that problem unless it came from a car with LPG installed and was from someone completely trustworthy,so its a bit of a dilemna. My thinking is to persue least expensive options first. :y

Point taken  :y I was fortunate as at the time, i had 2 lpg vectra's......so swapping parts from the one without the missfire didnt cost me anything and nailed down the problem  :y