I have a fairly modified 2002 R53 JCW with 110,000 miles (headers w/ 200 cell high flow cat, RMW tune, 550 cc injectors, newman camshaft, intake, and 17% reduction pulley). I threw an engine code a couple days ago saying I had a misfire in cylinder 1 due to the coil pack. At this point in time my car sounded like a subaru/truck/Harley and the DSC would not turn off. I changed the coil pack and the ht leads. The engine code turned off and I thought I was in the clear. Then on the highway around 60 mph if I were to slightly accelerate it would sort of stutter and make a popping noise like a misfire would cause. Before this I didn't have any issues. I replaced the spark plugs less than 3000 miles ago as well as cleaned my throttle body and checked my BPV. I have found on these forums that this can be an issue of a burnt valve, bad fuel pump, camshaft position sensor, etc. I was wondering if I could get somewhat of a comprehensive list of things that are possibly wrong. I am getting a compression test this week. Help!

 

Assuming it's P0301? Did you clear the P code after replacing the coil pack and is it now back on? Lots of really good information about this in this NAM thread here. Not the greatest of news, but it does provide some useful insight.

 

The check engine light did not come back on. It is currently off and has been for 2 days but is still misfiring. I did a compression test and found that all 4 cylinders are at 150 as they should be and the spark plugs were all good. I am expecting it is an injector problem at this point, but can't be sure.

 

By any chance, did you coat the threads of your plugs liberally with anti-seize? Sometimes, that will cause mis-fires.

 

No kidding? I did do that but never would have expected a misfire from it.

 

Yes, don't use anti-sieze. Porsche doesn't recommend using anti-seize compound on spark plugs for any of their engines. The bulletin applies retroactively to all models and the theory is that the anti-seize tends to act as an electrical insulator between the plug and the cylinder head. This could have detrimental effect on the firing of the spark due to the loss of a good, consistent ground connection. Keeping those findings in mind, I make the same recommendations for the MINI, don't use anti-seize compound on the spark plugs. This information, and more, can be found here.