Smoke Question

[carguy101]

The other day I noticed while I was waiting on a friend that there was some white smoke coming out of the back of my car. It looked like the condensation at first but it was too warm for that, or so I think. I am thinking it is not condensation because the other day it was just kind of hazing out of the back when it was turned off. I have only noticed it on start up and up to about 10 minutes of driving mostly.  It doesn't do it all the time from what I can tell, but that may not be saying much.  I also have noticed that it seems to be running a little rich by my guesstimates by there being more exhaust on my bumper recently. My gas mileage around town has been down a little bit as well. What are the possibilities for this, thoughts? Is it just a start up thing or should I have other concerns?

[DesktopDave]

If the car was really hot it might be coolant.  If you're valve seals or rings are going it might be oil.  Rich running is typically black smoke, not white.  It should smell like oil or coolant if you have a leak.

How cold was it outside?

[DesertEagle]

I had a problem with whitish smoke that might be water vapor.  In my case, there was enough vapor to form a small puddle under the tail pipe.  The exhaust smell was so bad all the neighbors on the adjoining properties would go inside when I'd let the car warm up.  The puddle, though, smelled like water-not gas.  I used a DVM on the back of the O2 sensor connector in the engine compartment to watch the a/f ratio.  The DME would bring it up to .700 to .760, hold it steady for a second or two, and slowly drop it into the .600's before it went completely erratic.  Then, the cycle would continue again.  
Ultimately, the problem was with the AFM.  The resistance sent to the DME no longer correlated with the opening of the vane sensor, so the DME had no idea how much air was coming in.  I believe the vapor out the exhaust was caused by the engine running rich.  Most likely, the cat was converting the excess hydrocarbons into water and CO2.  Anyway, I replaced the AFM and the problem you described stopped.

[carguy101]

Thanks guys, the car was cold and still warming up at idle, still in the blue section, it was cool but not cold out 50s or 60s iirc. And is a DVM a digital volt meter?