AFN: Kurbelgehäuseentlüftung - stark schwarz russender Motor | Posts 16+

Your soot problem is definitely caused by a leak. I have the same problem, although not as severe.

I once forgot to put the cap back on after I added oil.

While driving on the highway, I was surprised to see that everything behind me appeared black. A friend who was driving behind me said it looked like I was dumping sacks of soot out of my exhaust pipe.

When I finally opened the hood after 250 km, I saw that. There was a cover on it, and that solved the problem with the soot.

Regards,

Manuel.

@Manuel Thomas: That's strange, because if it's drawing air through the oil filler cap and the crankcase ventilation system, the MAF sensor should report a lower air mass -> resulting in a lower fuel injection amount due to the diluted air.