kybar

I have a 97 mustang 4.6 litre and it started missfiring and running really rough RPM's jump at low speeds and it occasionally backfires, I have been having this issue for awhile now and been babying my car, and recently my friends mustang started doing the same exact thing. Is this a commen problem?? OBD2 shows missfire 5 in both engines... i have played the throw parts at it game and still nothing..

cliffyk

What parts have you thrown at it?

kybar

Plugs, wires, coils, injectors and even tested the compression thats showing good. And jeff even changed out the fuel pump in his car, it acts almost as if its off timing or its starving for gas. I mean they are identicle problems,

98redstang

You change the fuel filter?

Brute03

cleaned the MAF sensor?

uberstang1

You can check the IAC and TPS, they can cause those symptoms but I doubt it would explain the CEL.

cliffyk

Check the fuel pressure, a bad pressure regulator can cause problems as you describe...

n0th1n2kn0vv

I had the same problem with my 5.0 but I don't remember the code. I don't remember backfire but a couple times it even stalled when putting it in reverse (auto). I never hesitated to put it to the floor tho. Turned out to be the MAF sensor.

kybar

So i cleaned the MAF, added a fuel pressure regulator and gage right before the fuel rails and changed the fuel filter out.. The car is actually running a hell of alot better but im still popping 2 codes. And the one i have found a million times on these forums but no direct fix for it.. im popping P305 cylinder 5 misfire, and a P1443 evaporative emission valve low or no flow, Would this valve cause the misfire? Or anyone know where exactly its at on the mustangs, all i can find is were its located and how to fix it on escorts and rangers...