you have a blow-by/bypass issue... that looks like crankcase buildup. I had that happen on my blower with the stock bosch bypass valve setup when I firt got it. if you have that tube running from the valve cover to the airbox/ inlet of the blower. ditch it.
heres two pics of plugs.. both are from drivers side, starting at the front from right to left. so.. 8 - 7 - 6 - 5 Obviously having both sides would be more helpful, but my car is against a wall..
Seem a bit darker than normal.. but im not too sure about that.
These plugs are 2 seasons old, as i only drove it for about two weeks last year. Theyre on the list of things to do this year. I heard some detonation last year a couple times but let off right after. I know my injectors are small for the top end.
Here's a pic of my pvc system..
The hole in the drivers side VC goes to a catch can with a breather. No longer connected to the powerpipe. The "box" has a hose that goes to the powerpipe. And the normal PVC location still has the stock hose to the intake.
I took the charge pipe off and that is dry along with the throttle body, so how does the oil get to the inlet from blow by?