Last night I took off the cheap/rattling muffler shop catback that my 99 Si had and install an OEM one that I bought on Craigslist. This morning on my way to work I noticed blue smoke coming out from the exhaust. This is the first time I've seen this and it has never done this before. No other issues on the car, but an oil leak that I think might be coming from the rear main seal.

Could the oem exhaust somehow be causing this or did something go wrong all of a sudden?

 

Probably have better pressure, causing you to now run rich?

 

Hmmmm...weird, I'm hoping it's not something serious because it was not doing this with the crappy exhaust.

 

Reset your ECU.

If running rich is the problem then the ECU should sort it out since it's a oem exhaust.

 

blue smoke means its rich i thought that was black smoke? hes burning oil or old oil that is burning out from the exhaust from the previous owner.

 

White smoke is lean, blue smoke is rich, no? Also, the "old oil in the new exhaust" idea sounds plausible.

 

White smoke is lean, blue smoke is rich, no?

 

White/Blue=oil. Black=fuel.

 

Took the car for another drive and there is no more smoke. I think that the previous owner had oil in there or from all the sprays that it was soaked with. I am starting to smell burned oil though, but I know it's from that leak that it has. It has the be the main seal, at least I think, because it's coming right from the area where the transmission meets the engine. I've replaced the oil pan gasket and the evap little canister seal, but oil is still coming out from that area.

 

A new thread devoted to that problem would reveal the best results.