Scjar

I have a '99 Mustang GT 5 speed. I had a misfire problem a while back, at least 6 months ago, and took it to a guy that my dad new who worked for Ford. Well it was fine for a few months, but this past month the CEL came back on and it was a misfire again, same cylinder (3). Well, i decided to try stuff myself this time one thing at a time because it seems like my pilot bearing is going badafter he replaced the clutch when he did the misfire. Well I have replaced the coil pack on cylinder 3 and replaced all spark plugs. And it CEL was cleared, then came back on with aCylinder 3 misfire. The guy supposedly cleaned the injectors and replaced cylinder 3 injector 6 months ago. Could it be the wiring? If so how much would that cost to get fixed?[/align]

kylebgt

Misfiring is typically caused by a bad fuel injector, spark plug, vacumm leak, bad gas etc. Since you have already tried most of this I think that you should make sure your a/f ratio is correct. Also check the timing. 99percent of the time a misfire is caused by something small and inexpensive. A cracked piston or blow ring could also cause it but that would be very noticable. Good luck

Brute03

have you checked the compression in that cylinder?

Scjar

I havnt checked the compression or a/f ratio. I don't really have a place to run it on a dyno or anything anywhere close. The closest one is probably an hour and a half away. Is there a way to do it without needing a dyno?

kylebgt

Well I have never been to a dyno but I am pretty sure that they do not tell you your a/f ratio, and I know that they wouldnt tell you your compression. You can take it to any mechanic to have both those tested. Shouldnt cost too much.

04mineralgreyGT

On a dyno they will hook up a wideband 02 sensor to it and check your A/F ratio. That is one of the key things to get correct when dyno tuning a car. But I am sure that a mechanic could do it.