Yesterday our -08 R55 with 75k miles Cooper S started sputtering like it was out of gas on the highway at 80 mph. Tank was full.

CEL came on. Ran unevenly and got worse and worse for every mile. Barely made it the 30 miles home. Stalled a few times. No idle; needed to keep it at 2000 rpm to keep running.

Plugged in my Carly for BMW and pulled the codes:
2D52
2DCC
2DCD
273D
2781
277D
2779
2775
2771

What is your opinion on what could be wrong?

 

Carbon on carbon the valves first choice.

 

Read the fuel pressure, possible HPFP failure.

Not usual for the car to misfire across all 4 cylinders and slowly die on the FWY due to carbon, most problems with carbon buildup are at start up, low power symptoms accompanied, but not to just all of a sudden start dying when warmed up.

 

Thanks!

 

I took it to Mini dealer. Turned out to be a molten spark plug.

 

Cool for a quick fix, but why was the plug molten?..

 

Good question. They are diagnosing it now. Given that it misfired across all 4 cylinders there is something else going on.

 

Lack of fuel creates a lean condition, melting occurs. I still suspect you may need a HPFP.

 

Makes sense. The dealership continued diagnostic and discovered that there is no compression in Cyl 1. They think it may be hole in piston or valve. Since there was misfire on all cylinders, a hole in cyl 1 was likely not the cause. Rather, it more likely started with HPFP. Since HPFP is covered under warranty, I wonder if resulting faults like hole in pistons for example would be covered too?

 

also they said they need to remove head to the tune of $750 in labor to see what happened in the cylinder. Would be cheaper to put down camera in spark plug hole, no?

 

It would be cheaper to use a boroscope, but you can't see the full spectrum of what is going on inside the chamber or how valves or rings look. But a hole in a piston will be blatantly obvious with a boroscope.