Hi guys/glurs: My vs been blackfire lately, not that often normally happen on free way driving, but the airbox start to becom small pieces of plastic, sine I put in a new one last moth I'm not going to put in another one Hence **** load of packing tapes being use It still look like a box anyway :P Talk to a LPG shop,the advice I got is change the lead to steel one& new NGK gas spark plugs. then a mate who is Holden mechanic, said that steel lead will not work with the ECU, so I fit in set of new holden lead&NGK spark plugs. ( oh, the F*** lead is not that easy to change, the **** thing is worst engineer I have never see, ) run good coulpe weeks but start blackfire again Any idea ???? any good LPG shop around MEL can fix this ???? THANKS GUYS Some original photos have not been recovered yet.

sounds like poor tuning. Are your converter/mixer stuff all ok? how about your iginition timing. You might be getting a rough patch.... is the backfire just at one gear/rpm, or is it all the time..?

Will get the converter/mix check tomorow VS iginition contron by ECU dont want to touch it backfire any gear/rpm as long as you push gas a bit hard I have to go to the place where i got the LPG installed, any results will let you guys known. thank for your help

Dude Test your AFM as I had my VL N/A on LPG and ULP and I was getting problems with backfiring ,I changed my AFM and it was all good ,but could have been isolated to my motor Bit still worth a shot to test out Hope it helps... Some original photos have not been recovered yet.

AFM might just be out of adjustment in that case .. reading too high .. Not 100% sure on the VS conversions, but a VL LPG conversion pretty much disables 90% of the EFI system, and the ECU comes down to controlling just ignition timing .. backfires could be caused by the ignition being too far advanced perhaps, which could be a result of an incorrect AFM setting ..

the problem with the ecotec motor is the coil packs. the reason they back fire is because on the intake stroke, there will sometimes be a bit of gas left in the Cylinder and because two cylinders share the same coil pack, there can some times be a spark on the cylinder that is suposed to be sparking AND the cylinder that is on the intake stroke, and becuase the intake valve is open the ignited gas flows out and blows up airboxes

Sounds like it's running lean. Really needs to go on a dyno. How long since the gas system has been serviced? When I worked for holden we uses to change plugs on gas cars from VN-VX @ 20,000kms and gap them down. But your gas systemhas to be in good nick, Also depends on gas system brand and set up ie: stepper motor in vapour line or feed back to diaphram. Could also be something as simple as 02 sensor. should be at aboult 450mv cruising

Id have a guess and say that the problem has been fixed almost 4 YEARS AGO. When this thread was created.