Car Analogy

Your description is apples and oranges. Beating the crap out of it vs sitting in traffic. Driving hard in the twisties might sound like more of a beating, but that might not be the case for heat at top of motor.

It may indeed be heat, but what is the reluctance to investigate cover causing a physical interference with a wire, a connector, or a coil pack, causing an electrical issue?

As a test, maybe try running the cover with some thick or doubled up washers under the screw mounts, to act as spacers. The idea being to prevent bottom of cover from physically interfering with the coils and wiring.

Maybe tape the washers in place so they don't move when you place the cover down. Screws can then pierce the tape when you put them in. Use something wimpy like masking tape.

Also, your most recent post mentioned a cel using cover in traffic, but confirm what the code was. The code is for a misfire, correct?

Scigheras

A bit off topic, but always wondered what those rubber blocks are for??

engifineer

I am going with the idea presented by Porsche. I am going to guess shorting to ground from a coil pack via spark jumping through poor insulation to the cover plate. I would suspect possible bad insulation within the coil pack. Was the CEL a misfire code and is it always on the same cylinder?

Slowcrash_101

It was a 1399, no specific cylinder.

These are NGK coil packs they look to be same dimension as stock.

I don't know how I would check conductivity of wires with the cover on. In any case, the cover is uncessary, so

engifineer

The issue of jumping spark would be on the secondary side of the coil. Doubt it is from the wires since those are 12V going to the primary and as long as the insulation is not damaged you should not be shorting there. But on the secondary, high voltage side of the coil if any associated insulation is in poor shape it may not be visible to the eye but could allow a spark to jump causing a misfire. This is what I am thinking. It seems like there should be sufficient gap between that part of the coil and anything around it, but without de-potting them it would be hard to see that.