i got a crx 2 months ago and there's black smoke comming out of the exhaust... it's leaving a residue on my back bumper. the guy i got it from told me the engine has type r parts, but not which parts were changed. he also said that the engine was rebuilt 60 thou ago. also note i have greddy exhaust system and headers. am i running to rich, and if i am what are some steps to making my exhaust nice and Not Black!!