I have a 2005 cavalier base coupe with an ecotec 2.2. The engine has less than 35,000 miles on it. I noticed that it would blow a puff of smoke after I would do a hard shift. well my cat convert got clogged up so I had it totally cleaned out. it does run better but I have noticed an increased amount of smoke coming from the tailpipe. I called my mechanic and he thought it was from the oil I was using, I was using a full synthic, so I switched back to regular oil and guess what it still smokes.I have not done too much to my car engine wise, I had the cat cleaned out and I am running an aftermarket APC 5 inch tip exhuast. A co-worker of mine told me that I was blowing a whiteish blue smoke and it smelled like oil burning. I was wondering if anyone has had this problem and how do I fix this? whit parts do I need to get or is there something I can add to the engine? Thank you for all your help.

are you low on oil or anti freeze?

I am fine on oil and on antifreeze

Blueish smoke means that your burning oil.

white smoke means your burning antifreeze

black smoke = running rich.

which do you have??

Mine does the same thing. when i shift at high rpm, it does it. Mind you mine does not have the stock exhuast and all sensors are fine. and it's black smoke. When you shift hard you have access fuel left hence black smoke. you may have another issue but this is nortmal for my eco.