Hey guys I'm looking for some advise my 02 R53 is having a misfire issue and throws the P0302 code out when it does misfire. I've tried all the simple things so far, I've gotten new cables, swapped sparkplugs round to see if the code would jump to another cylinder, tried a brand new coil pack, and swapped the injector with another one. It still resides in cylinder 2. I have yet to do a compression test or a leakdown test but the way it misfires is odd to me. If I start my car cold it always starts fine and STAYS fine even after warming up. I can drive it for 4 hours and not have a single issue, but after I turn it off and restart it when the engine is hot, sounds like a subbie, it starts to stutter and throws the flashing SES light on saying misfire in cylinder #2. It will rarely clear up with a bit of throttle but it if it does it will stay fine for the remainder of the trip and runs strong as long as I don't turn it off for any reason.

 

Seems to me it must be in the fuel delivery system somehow. The ignition coils are paired so if it was that, you'd more likely be seeing this in two cylinders vs. just one.

I see you swapped the injector and the problem stayed with the #2 cylinder. But what about the injector DRIVE from the ECU? If you have access to another ECU you might swap it out and try it but you can check the wiring to the injector.

I suppose it could be a valve or a problem in the cylinder but I think that is less likely since this comes and goes. If you have a burned valve for instance it would stay burned all the time. Electronics, on the other hand, can easily be intermittent and perhaps this issue is triggered by the ECU being hot vs. cold when you start the engine.

 

Yeah I've starting to lean more towards an ecu problem or some sort of electrical issue because of it being intermittent. Since I can drive for hours with no signs of it, if I start it cold.