White smoke in the cold

[Justin_K]

I have a 1995 240sx and when the weather started to cool down (below 40) it started smoking. It only smokes at night (when it cools down) and gets worse as car gets warmer. It's hard to tell what color it is since it only happens after sunset but it looks white (no blue). At idle it evaporates quickly, when revved quickly a large puff comes out, and when the rev is held out at ~3500 it smokes but not as bad as quick rev. I've smelled it and it doesn't have a sweet or gas smell. The car also drips out the exhaust pipe and on my finger has some black residue.

Thanks for any help,Justin_K

[navysnail]

when the surrounding air is cool enough to cause a change in the vapor pressure of the hydrogen hydroxide in the exhaust system, it will precipitate on contact with the cooler air into a liquid form of hydrogen hydroxide. the black stuff is an organic compound that occurs as a byproduct of combustion, and the liquid helps it run out of the pipe.

[S13inBatnRuge]

that has got to be the most technical definition ive ever seen on here. +1 navysnail

[Touchdown038]

Yeah really... nice one.

In short, your car will make white exhaust when it's cold. Nothing wrong, it's normal.