Cyl 6. Misfire? HELP!!

[farley463]

I'm trying to chase down a cylinder 6 no load/idle misfire on my 97 z34. So far I've tried swapping a coil pack, injector, spark plugs, new plug wires, nothing seems to help. The engine is stock with the exception of 95 cams with 10° exhaust retard. Like I said the miss only occurs at idle with the throttle closed. The only thing I haven't checked is compression, but I presume its fine since it runs good under a load. Tomorrow I'm going to set it back to stock cam timing to see if that helps. Other than that, I'm out of ideas. This engine has had new head gaskets put on in the last 1700 miles.

[3400-95-Modified]

I suggest a compression check and leak down test to ensure a valve isn't stuck open. Idle it will miss more if it's a valve leak vs under load since it has less time to bleed off the compression when the RPM's are up.

[farley463]

Hmm, alright, ill have to try that. Like I said I did have the heads off 1700 miles ago and I didn't notice anything out of the ordinary. I'm going to try resetting the cam timing back to factory spec to see if that helps any. Ill let you know my results...

[farley463]

Update. Set the cam timing back to normal, and she purrs like a kitten. 3 days later I'm averaging 24mpg between mixed city/highway driving, and no codes. I'm amazed at the gas mileage I'm getting now. With light driving I'm at 85 miles and still have more than 3/4 tank. Then again, I guess that's what happens when you stop driving like a dick. Lol.

[pocket-rocket]

Lol, funny how that works. I got 12mpg average one tank in the 92, and I had fun that week too, lol.

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[farley463]

Must be nice having a 5 speed! If I drive like a dick continuously ill get about 10.5. Lol. Then again thats with 95 cams and 10 degree exhaust retard so I'm sure its improved now that its back to stock timing

[Tyler B]

any DTC codes?? if it has a randomn misfire code 2 out of the 3 ignition coils could b bad causing it to misfire.