ok I have asked this before and I searched and everything. I cleaned my car today just to see how bad it was. It's was very clean went out for 30 mins and I can start to see black deposit getting back on the car. I did a compresstion test and everything was 220-240. I changed valve seals while changing the valve train. what else could it be head gasket? running rich? please help me out also i can smell exhaust fumes in the car every now and then. I do have a cat on and every thing. well hope you guys can help me out thanks
Luis

 

Chipped ecu?
Pcv System?
Converter?