Yet more strangeness with my 2008 Cooper S.
Limp mode comes on almost immediately after starting the car for the past few days. This displays a half-filled engine icon on the dash and greatly limits power (feels like the turbo is disengaged).
The engine itself sounds okay. It does audibly misfire a couple of times per minute when idling. At higher engine speeds, it either doesn't misfire, or I can't detect it.
There is no CEL. When I plug in my scan tool and look at the OBDWiz software, I see no pending or stored codes. The only thing out of the ordinary is a high number of misfires in cylinder 1.
What are my next troubleshooting steps? Could a failing valve cover cause this? I pulled in the coil off of cylinder 1's spark plug and the hole was a bit oily. I hesitate to replace the valve cover without knowing it's an issue because a new one is $300. It does have oil residue all over the top of it, but I can't tell if this is because I spilled it when topping up last time, or a leak.