LPG misfire help

[mac1]

hi all im new to this site. iv just had lpg fitted to my v8 and at first it was running fine. after a couple of days its developed a misfire. this only happens when im running on lpg it totalling fine on petrol.

i took it back to the garage that fitted the system. they did some test and located the cylinder that was at fault is the rear right hand cylinder. he said there a weak point in the ignition system and due to the fact that lpg needs a really good spark to burn it not fireing properly.

it has had a new set of leads, plugs, rotors, and caps only 6 months ago iv changed the plug on that cylinder still no better. what to do next.

is there anyway of boosting my spark?

 

[Ursus]

an aftermarket ignition system or maybe booster coil would give you more spark. did you try changing out your coils?

 

[cribbj]

I'd try a set of Iridium plugs, then if you don't get any results with those, have a go at this forum:

http://fuelsforum.rasoenterprises.com/viewforum.php?f=5&sid=6f00457ee1c5bbc7b8f78a739c4dae5d

It's Canadian based, and there are some very knowledgeable LPG guys who hang out there. The discussions tend to center around carb based LPG systems 'cause that's all you find in North America, however your problem sounds like it's ignition, so I think you'll find some good advise there.

I'm going to move this thread into our Alternative Fuels subforum, as you might get some attention from some other LPG users there.

BTW, which system was installed on your car, and were you happy with the installer?

 

[mac1]

Hi thank for the info. The system was installed by a small garage that specialises in gas conversion. they have carried out an almost identical setup to a lexus 400 before mine with to trouble at all. The garage is called south east auto gas. They used a sequential gas injection system from a company called zavoli. They sound like a good system from what iv been told. It a multi point system using 8 individual injector.

 

[Sudsy]

Try closing the plug gaps and see if this fixes the problem. If it does Then get yourself a good coil and ign setup and then open up the gaps again. A lot of factory setups can't handle the gas spark requiements properly so gaps have to be closed to compensate.

 

[converted]

yes I have had the same issue with my Landcruiser backfiring on gas and not on petrol. Its due to the ign. I found that mine was caused by cleaning the engine and having a small amount of moisture i n the ign system. Just WD40 all leads, plugs etc etc and see if that makes a difference. It did with mine....

 

[gloverman]

What spark plugs are you using with what gap? Cheers