I was just doing a little tuning session in my driveway. I would let it idle, then hold it at about 1500 rpm for 30 or so seconds, then 2000, then 2500, etc etc. After holding it at these higher-than-idle RPMs for a couple minutes i noticed a burning smell. I've smelled this before, usually just after cruising at highway speeds. This time I actually saw smoke coming from under the car since I was in my driveway. Immediatly killed the engine and ran over to take a look and saw all kinds of smoke coming off the cat.

I may be running rich, I'm not sure. Havent got that far yet

I work under the car often and it leaks a little ATF from where the cooling lines enter the transmission. I'm sure some splatters on the exhaust pipe from time to time, and I'm sure I also wipe it all over the exhaust pipe when I get it on my hands. Is this most likely the smoke? Now that I think about it, the smoke does kind of have that "sweet" burnt smell like how hot/burned ATF smells, but that could just be my mind....

Is there anything else that could make smoke come off the cat?

 

Yep. Ever notice how headers smoke when you start working under the hood? Usually it's just oil that managed to get on the headers while you were working on them or around them. Probably the same case here.

However, I'd take a closer look if it keeps smoking for an extended period of time.

 

What did you ever figure out on this problem. i've got the exact same thing going on and I'm trying to figure it out.

Thanks.