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View Full Version : Will oil on the coil pack cause misfires?



mixofia
10-14-2014, 05:15 AM
I get a CEL fault, P0308 misfire cyl 8, that only seems to happen at load at around 4000RPM - my guess is when the intake flaps open. But I can clear the code and drive easy for days and not get a CEL.

I was going to swap coil packs to see if that was the cause, but when I removed coil packs 7 & 8 I noticed there was oil at the bottom of the shaft. Is this possibly a leak in the valve cover gasket - and if so could it be causing the misfire cyl 8? I'm a little confused because there was also oil at the bottom of coil pack 7, but I never get a misfire on 7. Scanning the forums, it seems another possibility could be a PCV valve?

And what about the intake flaps - could this be 2 different problems?

I m looking for ideas/suggestions?

Regardless, am I ok if I drive it easy for awhile as I track this problem down?

Dave01.5Afour
10-14-2014, 08:36 AM
It could be the valve cover gasket that's leaking but there is also another gasket a little further down in the head that is the more likely culprit. That gasket looks like a series of rings connected by a line.

You can vacuum out the oil to eliminate this as a cause but you probably just have a bad coil pack or plug that needs changing. Intake flaps shouldn't be causing a misfire problem on only one cylinder.

If you have a random misfire you can drive it. If you have a constant misfire, you shouldn't drive it.

Fmscell
10-14-2014, 09:18 AM
You could also have a plugged cat starting (of course if the coil swap doesn't follow the corresponding cylinder)

mixofia
10-14-2014, 11:27 AM
You could also have a plugged cat starting (of course if the coil swap doesn't follow the corresponding cylinder)
Do you mean a cat starting to get plugged? Can you tell me what other symptoms might indicate a plugged cat?

I have already replaced the coil pack, but the misfire still happens - only on cyl 8 and at 4000+ RPM. I have not replaced the fuel injector yet. But there was some oil on coil packs in both 7 & 8.

mixofia
10-14-2014, 11:29 AM
If you have a random misfire you can drive it. If you have a constant misfire, you shouldn't drive it.

I get no CEL light if I drive it easy. Only when I cross 4000 RPM.

Dave01.5Afour
10-15-2014, 05:03 AM
Is your car direct injected or multiport injected? Are there any other codes stored in the ECU? Can you post a full autoscan of the ECU?