Three weeks ago my 944 Na started running rough at low rpms, below about 2K, so today I changed the AIV as it had a dead spot in it. I didnt start it prior to the change ( battery low) charged battery started it up. Ran right away,but wouldnt idle (still) and had white smoke coming from under the car (lots) ...smoke came in the car from the shift boot (lots). Above 3K engine seems ok, has a miss, but not bad, below 3K sounds like it is really bogging. does not rev like you would expect. Ran it for about 30 minutes, water and oil stayed the same. Car smoked for 40 minutes after it was shut off. It smelled like atntifreeze, saw no water level change or any leaks. Where is a good place to start?

 

It doesn't take muchcoolant in the combustion chamber to make white smoke in your exhaust. Sounds like you may have a head gasket failure. This couldexplain the rough idle at low RPM and definitely would explain the white smoke. My guess is that if you were togo on a short ride, like around the block for example, you would notice a definite drop in the coolant level.

 

The smoke is not comming out the tail pipe its comming off the outside of the pipe, can this be a bad cat?