So my car is getting a misfire code in cylinder 1. It only happens at the end of 3rd gear above 5k rpm. The A/F will read at 12.4. I just polished the valve cover earlier today and pulled the coil packs out. I may have gotten a bit of water in there, would that be what causes this? I drove the car for about an hour pretty hard before it would start this CEL flashing and stuttering. Is water going to get in there gonna make it freak out like that?

 

Possible if you do in fact have water in there, it is more than likely grounding out the coil. Electricity always follows the path of lease resistance.