I haven't driven the car in a couple of weeks, but about a week before I parked it to change the intake plenum, it started backfiring on me. It only does it when I first hit the gas to rev the motor or if I punch it as I downshift or punch it in a low gear. It sounds like it's going to blow the filter right off So last night I finished putting on the GT40 upper and I started the car and as I revved it lightly, it still did it and the battery was unplugged long enough to clear the KAM. What typically causes a backfire upon the throttle initially opening and how can I fix it through the TwEEcer? I notice my headers got pretty hot really quickly. And the car sounds way more lopey than it did before. Last time that happened, it was the timing way off but I checked the base timing and it was about 10° or 11°. So maybe it's a fuel issue All I did is put the intake on and fixed the driver side valve cover so I don't know why it would suddenly have issues
Don't over think this issue John Most likely something basic like a v leak, bad electrical connection, or the like. Since you checked the spark and all looked good, you would think the prob is fuel related. If it does it in CL, what do your kamrf's & lambse values look like? Good Luck Grady
What ended up being the fix? Mine is doing the same thing for the past year after I installed H/C/I same exact symptoms.
A fellow stanger friend just, literally, just went thru the same issue. He checked timing and all other stuff. It was a vacuum leak. Take a can of carb stuff and spray around intake if there are changes then there's your problem.
