I have the following problem:
My girlfriend's BMW ran on 3 cylinders. After the diagnosis, the ignition coil on cylinder 1 was replaced. She drove around in the car for 3 weeks.
It is actually running perfectly now, but there is a lot of smoke and it smells of burnt oil.
In the cold state everything is OK, but not so as soon as it is warm, especially when starting up and at partial load. No smoke is noticeable under full load.
It's been in the garage for a few months now, so now I'd like to take the time to solve the problem. I suspect that the catalytic converter was damaged by driving on 3 cylinders or is dirty with oil and gasoline. Is that plausible or rather improbable? I discovered a trace of oil on the valve cover seal, could it be because of that? P101b is also stored in the error memory. According to Google, this is probably due to the "Valvetronic", but it can also be because I had to bypass it.
Vehicle data:
BMW 318i E90
Year of construction 2006
Engine code N43.