Hi.

My 2003 Mini Cooper has started intermittently missing. It will run just fine at startup, but then will intermittently start to miss. It throws the P0301 code for cylinder #1 misfire. I've changed the plugs, wires and coil pack. I've now found out that the #1 injector doesn't appear to be getting signal to send fuel. At startup, the engine runs fine and the injector appears to be working fine, but within a very short time (seconds/minutes), the #1 injector will stop receiving signal. The injector function was tested with noid lights. Any ideas what might be causing or how to diagnose further from here?

Thanks.

Chad

 

One thought is to swap the injector with another cylinder. The ECU will shut off an injector to protect the cat or a cylinder. May be you have low compression in #1 and ECU detects abnormal combustion detonation - including wimpy one at #1 . Have you done compression test on all 4 cylinders? I don't know a whole lot about the Siemens ECU management but I try.

 

Moving you to the Stock Problems/Issue area.

With long distance diagnosing the more you tell us the better chance we have of helping. This a R50 justa or a R53 S? How many miles? Regular gas?

With that code and regardless of the injector, try a dollar bill test. You flutter, you fail and chance are the valve is burnt.

 

No compression or leak down test yet. R50, 95K on the odometer, and running 93 octane gas. The thing that has me really puzzled is the fact that the miss comes and goes. Lately it seems to come after it warms up, but sometimes it runs great until it decides to start missing. It definitely has a tendency to start missing when at idle though.

 

Would check the wiring harness and then switch an injector around as pnwR53S suggested.