i have a 2003 chevy monte carlo ss with a 3.8. It got an engine code (P0171) saying bank 1 too lean. I cleaned the MAF and replaced the upper o2 sensor. before i replaced anything, it idled real rough, and had a slight amount of smoking, but i did not think to pin point it, until after i worked on it a bit. at first, the o2 sensor smoked, but it appeared to have burned off something since it has stopped smoking at this point, but almost directly below the throttle body, there is what appears to be some liquid, and it is smoking like hell. The idle issue is still there, but the engine code cleared itself on its own.
I also just drained the trans pan and replaced the filter and gasket. i spilled a tad bit of atf.


Any help is greatly appreciated!
Andrew
btw, this site is byfar the most useful site on the internet for working on my ss.

 

The exhaust crossover runs under the throttle body. You didn't spill something on it, did you?

 

Coolant runs from the LIM into the UIM, through the throttle body and back around. You could have a throttle body or UIM gasket failings, allowing coolant, under pressure to seep out. In this case, it seeps on to your exhaust cross over pipe, thus creating the smoke.

I would advise getting your hands on a radiator pressure tester. Car cold and and off, hook the tester up. Pump it to about 13lbs, then listen for hissing and look for signs of coolant leaks (such as air bubbles where gaskets are).