Im having a problem with my '94 Lexus Es300. For some reason when i turn on the air; i get a burning smell and i dont know where this is coming from. My car used to smoke bad because the o2 sensor inside the tranny was messed up and i got it repaired. Also when i lift the hood up i can still see a little bit of white smoke coming from the top part of the car (behind the engine). If anybody can help me solve this problem, it would be greatly appreciated. Thanks

 

My guess would be that it's a leaky valve cover gasket.

 

Yeah probably the valve cover gaskets. Look at the back of the engine to see if there is any oil leaking down or anything like that.