I am stumped every time I shift know matter what rpm I get a pop and a backfire. I know its not from having any exhaust issues because I have ran a strait pipe without this problem. I am concerned that it is a burnt or bent valve. I also have a periodical miss at idle but still no check engine light. I changed the plugs about 3k ago and they were NGK. The car runs great but has poor idle and this anoying backfire. I was told a bent valve will give you a check engine light and I would also asume it would give you drivability issues so idk. Anyone have problems with their injectors I have 110,000 on the car.... Thanks

 

What do you plugs look like. This will tell us allot! Drive though a parking let in fist, shift and right after it backfires turn the car off, coast to a stop and pull the plugs. Report back with your findings.

You also need to give us some insight into your setup? 100% stock? AFC? test pipe? recent tune up? What plugs? factory computer?