VS sII 1997 with lpg and petrol having some trouble with car back firing

[milesgt]

Hello I am new to this site,
just bought a VS sII 1997 with lpg and petrol having some trouble with car back firing through the air filter have changed plugs and new leads
It runs fine in cold weather but on hot days it start to backfire . Also when running on petrol runs ruff in hot weather

Could this be the censer on the harmonic balance been faulty ? Any help would be very appreciated

Thank you
Glenn

[bpefi]

Hello I am new to this site,
just bought a VS sII 1997 with lpg and petrol having some trouble with car back firing through the air filter have changed plugs and new leads
It runs fine in cold weather but on hot days it start to backfire . Also when running on petrol runs ruff in hot weather

Could this be the censer on the harmonic balance been faulty ? Any help would be very appreciated

Thank you
Glenn

First is the LPG system aftermarket or fitted at the factory & what sort of converter does it have ?? I have a lot of mods that will improve how it runs on LPG if your interested. PM me for further details

First you have ignition problems - the best plugs that I have found by far are Pulstar & they are available from the website linked below - My VS has had three coils die & never had a backfire EVER - they just seem to be able to use whatever energy is supplied to fire the plugs until the coil dies - there is info all over the web & they are big in the states but not over here yet - they have a capacitor built into them which creates a better spark - you will have to gap them down to .7 mm - Buy some new leads - preferably genuine as they are as good as anything if not better & reasonably priced. You need to check your coils output - if your scared of taking a lead off & getting booted just buy a new set of MSD coils off Ebay & be done with it as they seem to fail regularly. If it still does it after this you will need a new ignition module.

Hiclone, Fuel Economy, Hyclone Fuel Saver Pulstar Pulse Plugs Petrol Diesel LPG - Home

[Stugdum]

I had heaps of problems with backfiring on my VR which is dual fuel, blew up 2 airboxes in 12 months and I tried changing plugs, leads etc all to no avail. So I spoke to a LPG guy and he suggested changing the ignition module, which I did and I havent had a backfire since, and that was over 12 months ago. Not a cheap fix but it worked! Hope it helps you.

stugdum

[bpefi]

99% of backfire problems are ignition - check all connections though - you can loosen the plug leads at the coil & pull them off individually & check what spark you have - use insulated or plastic pliers & hold well back from the end of the lead. You could try wreckers & buy a coil pack & dfi module - I can buy the whole thing here for $60. Make sure the gaps of your plugs are around .7-1mm & you have to go one heat range colder.