yamanx

I got a 1998 GT with 89k miles on it. It has developed a miss on cylinder 3. I have changed plugs, wires, coil packs, injectors, oil in the motor, cleaning the K&N air filter recharged it and such, clean the MAF after air filter.. pretty much everything else BUT cylinder 3.

The car will also start to run rich if it idles too long. I pulled the codes with a ODB reader to get the cylinder 3 misfire. It also had 7 in there but that cleared up with changing of the wires. I can clear the code but it will come right back once I get on it more than once. Oh also the plug will be wet when I pull it out so the injector is spraying.

Any help would be awesome or donation of a PI motor

yamanx

I just pulled the plugs, every one looks good except for 3, it's wet a fouled. So I replaced with a new one and test drove it again. But before we cleared the codes we saw that 7 had come back on the misfire list. The car still idles rough but seems to clear up at higher RPM, once cleared and couple miles of driving number 3 showed back up. I'm confused and frustrated.. I was checking the O2 sensor data and the voltages from sensor 1 one bank 1 and 2 was around .010 - .5 were as bank 2 was around .8 on one and .3 on another. All 4 never really got around each other is this normal for the sensors? Could that be a part of the problem?

yamanx

No infinite words of wisdom? I've done searches and seems other people have had this problem but I've yet to see a answer to it...I guess I'm just stuck with a Mustang GT 4.0 haha.

ChalknCover

You wouldn't happen to have the code that it keeps throwing? Is it P0303? Other causes could be camshaft position sensor and the knock sensor, everything else I think you have addressed.

yamanx

I don't remember the exact code right now, I know it was a P0*** probably what you said. But this last time cylinder 7 came back into the mess. So it's missing on 3 and 7 again, I also took the mufflers off to see if the miss went away at high RPM or not..haha it's still there. But I just remembered that 3 and 7 are next to each other in firing order so I will have to check the camshaft sensor tomorrow in hopes of finding this little devil..

WhiteFoxGT

You dont have the 2 spark plug wires mixed up do you?

yamanx

I could only wish it was that simple...

yamanx

But if the cam or crank sensor was bad wouldn't that show on my OBD reader? Does the car get the timing from the cams or crank? Could something be wrong with the timing ring?

yamanx

Well I finally figured out the problem.. Cylinder 3's intake valve isn't seated...so guess the head is coming off..

Drew2672

How did you figure out that the valve isn't seating? Was it a compression test? I am having a similiar problem with cylinder 7 on my 98 but my compression test came back ok. Just wondering.