I just finished rebuilding 2000 Boxster 2.7L. It had a bad # 6 connecting rod bearing with a piston slapping, so the whole engine was torn down; rebuilt the crank and replaced the bad rod and piston with various new parts along the way (IMS bearing, etc). The engine starts and actually runs smooth at start. When it warms up I get a misfire and it runs rough at idle for about 30-40 secs and then smoothes out. The CEL is flash at that time, but turns off. This cycle repeats every few minutes. I can get it to recover faster if I rev the engine to 3000. The CEL code is a P0301 misfire on #1. It is the only code. I have done the following:
1.) Spark plugs are new. I swapped #1 & #3 spark plug and coil – no difference. The inspection of all coils were made and no cracks. Inspection of new plug in #1 looked clean.
2.) I checked the wiring continuity from #1 back to ECU and the O2 Sensor (blk wire) – all check OK.
3.) Disconnected MAF sensor and it take a little longer for the first misfire cycle. I also cleaned the MAF sensor and no change.
4.) Inspected all electrical and vacuum connections to make sure they are connected.
Any thoughts on where to look next ?
Linear Mode
