I was having misfire issues with individual cylinders on my 04 XJ8 and after paying my local repair shop to replace the coils one at a time, I decided to just go ahead and replace all the plugs and coils myself. There were a few issues with coil screws stripping and plug boots ripping and getting stuck on the plugs, but I finally got it done. Now it runs great but every now and then, upon starting, it runs rough and then runs fine as soon as I start driving. Then the engine light goes on and I get a reading of cylinders 1,3, and 5 misfire. I can clear the codes, and it runs fine until the next occurrence. I ran gas treatment through the gas tank to no avail. Any suggestions as to what else it could be?

 

Could you post the codes you get? That would probably be helpful.

Best regards,

Thomas

 

The codes I get are P0300, P0301, P0303, and P0305.

 

Hi @DresslerRW , sorry to hear about your issues. Can you tell us what your fuel trims are? Both STFT and LTFT for both banks? Thank you.

 

Maybe this could help:



Best regards,

Thomas