Recently my car has developed a popping noise from the exhaust on deceleration. It typically occurs at about 2000rpm but also happens occasionally during acceleration when cold. So far I have tried a fuel filter, distributor cap, rotor, plug wires, and plugs. I also checked for vacuum leaks and can't find any. I did find a bolt that backed out of the drivers side exhaust manifold so I re-tightened it. The car idles fine at about 500rpm with very little flucuation. The throttle blade wiggles a little bit which I blame for the slight ******* of the engine when the accelerator is depressed. Does this mean that there is another exhaust leak somewhere or am I having a fuel starvation problem that only occurs around 2000rpm? The engine seems fine. By the way it is a 305TPI A4 with and adjustable fuel pressure regulator set to 46psi on 19lb/hr injectors. Also the plugs look like the engine is running rich.

 

a lot of the time that popping is caused by a crack or a hole in the exhaust system.... ie an exhaust leak.. either get under it and inspect it, or have someone do it for ya.

 

check timing i had the same thing, engine running rich because of lean timing on highway when i let off it it would go pop pop pop popuntill revs went down..

 

i 2nd the timining....but thats cause i was running a non-stock timing table in my prom

 

It could be the air injection diverter valve, mine failed and the and the air injection pump was pumping air into the exhust all of the time, so it was just like a big exhaust leak and it popped like crazy on decel. There is a proceedure to check it in the GM service manual.