24vgti

Ok im new on here for a reason, i have a problem car in my shop right now, its 2001 mustang gt, 4.6L, this guy has his cats removed, x-pipe, and flowmasters on. he has rear o2 sensor eliminators on and a CAI. the car has a slight misfire at 1300rpms while cruise, and a slight misfire while idling. there are no codes in the computer at all. Ive scoped every coil and every injector for voltege and current ramping, everything seems to be fine. Fuel pressure is with in spec. EGR valve checks out ok. I just cant get over to think that b/c there are no cats it has a slight misfire b/c of a backpressure issue but i was searching around on here and found nothing about that so i think is out of the question. a little advice would be much appreciated, thanks.

Matt

silver03gt

Idle Air Control valve maybe? try cleaning it see if it helps. good luck

2000GT4.6

I have not heard of this problem with a car with no cats.

Do you have any way to check the A/F ratio? Is he running a non stock computer program?

24vgti

yea i seen he has a new IAC motor on it, and no i dont have a gas analyzer, so not sure if its a lean missfire or rich missfire. thanks

matt

24vgti

and yes its a stock computer maping, sorry, no chip, nothing