VS on gas destroying plugs/backfiring

[strgas]

NGK BP7EF gapped to 0.9 mm good set of low resistance leads with a spiral core , gas master , IC&E , top gun , bosch sports core , check your spark plug socket and see if has the rubber insert inside to avoid cracking the plugs and do not over tighten the plugs , check for vacum leaks around gasket and seal surfaces after repeated back fires gasket and seals become loose or split from the backfire pressures, I have seen IAC o rings leak injector o rings blown out of shape so check carefully for any leaks in and around the manifold , also looking carefully at the mixer set up if its a simple mixer ring it may no longer be sealed to the throttle body correctly if its a impco style system it may have splits in the rubber hose from the throttle body to the mixer

 

[strgas]

code 57 is normal for a non injected system as the power to the injectors is switched of by the gas system and results in code 57 , can be resolved by replacing the power to the injector pins at the ecm but not needed

 

[Old Colts in Oz]

Update - got the old girl driving again. I ended up replacing all 3 coil packs and the missfire is gone. Interestingly it's running better on LPG than petrol. On the freeway today the car seemed kinda jerky on petrol and when i flicked it to gas it actually gained power and was smooter. Bit strange as I'm assuming the plugs are set up for petrol. So in the past week I've replaced the tailshaft centre bearing, new leads, plugs, and all 3 coil packs. Expensive week!