I just installed the invidia v4 exhaust with a 70mm test pipe with the built in CEl fix. Well shortly after installing it the CEL came on so this test pipe does not correct the CEL. I put in 2 non foulers and went out again. I dont have a CEL yet but the problem i'm havin is when i'm sitting at a red light or at a stop, when i press the gas and RPM's go up as soon as they start dropping they just keep going until about 1 bar on the RPM meter is showing. The car shakes like hell and will regain itsself and idel fine. It only does it when i press the gas and let off. I press the gas, let of, the RPM's drop and go all the way to 1 bar on the meter, car stumbles and then regains after shaking violently. Anyone know what could be wrong? Possible idle air control valve? Maybe need an idle air re-learn? And also the car doesnt do it with the A/C on also.

 

Could be that you just need to reset your ecu and let it "relearn"

 

shouldn't be the reason. My car never did this once after putting on and taking off my test pipe 3 times.

I don't know what the problem is though, others will chime in.