White Smoke from Exhaust

[AlexSutherland]

My E30 325i exhaust has been producing a lot of white smoke especially in during cold weather and while on the throttle. I thought this was a head gasket or a cracked head but I doubt it. I've checked the coolant and oil and they're both clean. I also did a compression test to be absolutely sure. My car has a slight misfire on cylinder 5 or 6 for a while, I'm not quite sure. I thought the injectors might be bad. I saw the resistance of each and they're within spec. I also checked the injectors tapping noise and they all sounded the same.

My question is does anyone know what the else could be producing the white smoke? Could it be a leaky injector, do they sound the same as a functioning injector? Fuel Regulator? Or something else?

[SethB]

Does is smoke only when it's cold and go away when the engine warms up, or is it consistent regardless of engine temp? Is the smoke thin and dissipates quickly, or it is pretty thick and hangs around for a little while? It's pretty easy to trick yourself into thinking that vapor and steam from hot air on a cold day is actually smoke. there's a lot of moisture in exhaust air so in cold and dry air it's going to look pretty cloudy.

If it's happening regardless of engine temp, and is thicker smoke (as opposed to vapor), white smoke is nearly always coolant. Depending on the leak, it is possible to burn coolant without your oil or coolant looking milky.

[dnguyen1963]

By product of combustion is water which will condense into white vapor on cold days. If your car produces a lot of thick white smoke and, if it smells sweet, then it's most likely coming from burning the coolant.