I was pulling into a parking lot with my 01 A4 1.8t and the motor started knocking. CEL was flashing indicating a misfire. CEL code was cylinder 3 misfire. I replaced coil pack and nothing. Pulled spark plug and the electrode was flattened!! Either by cylinder or foreign object I guess.

Car has 155K. I always change oil with synthetic every 5k miles. Timing belt is fine. Any ideas what could have happened??? I'm going to do cylinder compression test today.

 

check the compression and pop off the timing belt cover and see how it looks. you should be on your third timing belt by now....

 

Yeah I just had the timing belt done a few months ago. I looked at it and it looks fine. Something internal is damaged. What the hell can cause that? Not a sludge problem either.