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Cylinder Misfire Again


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Well I thought I fixed the misfire issue when I changed the plugs after finding the #8 plug electrode bent to the point of not having a gap anymore.

Well, within minutes of starting a hot lap the same issue began happening. Engine missing and erratic power. I pitted and heard a tapping sound out of the engine on the driver side (just as before when I had the #8 plug issue). I pulled the #6-8 plugs and they looked fine. I did notice that when pressing the coils on the driver side, they were all firmly seated, except on cylinder 8. I could push it down 1/4" and it would push back. I looked at the end of the boot and the spring seemed a little further out compared to the other boots. I then started the car and it sounded smooth again. I took it out in the next session and same issue started again. However, the engine ran smoothly upon pitting. But, had engine code cylinder 7 misfire.

I left and went home. Drove smoothly even when getting on it. At this point, I was disgusted messing with it. Took out the race pads up front and back in with the hawks and street tire/ wheel setup. Bedded in brakes and all was smith as can be with repeated boost including some third gear pulls. Thought maybe I would change the #7 coil. A few weeks ago it was cylinder 3 misfire, then cylinder 8 misfire (understandable with bent plug), and now cylinder 7. I'm not sure what to do at this point.


On a lighter note, I put the race pads and Nitto nt01 on the wife's otherwise stock Boss 302 and drove it to the track today. I shaved 2 seconds off my best time in my gt500 after my second session! Feels much lighter on its feet. More balanced. Not as stiff as my gt500 ( more roll in boss). Ass end wants to come out a little more easily. Shifter sucks in the boss. Overall smoother car though.

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JMO - like I said before - you might have a cat breaking down/apart or an electrical problem . I would suggest dropping the cats and check them to see if they are still solid peices. I refer to this because something had to close that gap on the #8 plug so if for not anything else at least you check to make sure your not getting chunks of the cat material getting into the motor (I've seen this on a car-passenger side was in pieces while drivers side was solid) . It's the only thing that I'd suggest at this time as a starting point.

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