Car stalls / white smoke

My husband’s 2001 Nissan Maxima stalls in the AM or whenever the engine is cold, and it hesitates when he is driving for about the first 1/4 mile. There is also a thick white smoke that comes out. He has brought it to a service station (they said nothing was wrong because nothing showed up on their computer after the diagnostic test) and then to the dealer. The dealer said nothing showed up on the computer, either, but they claimed the air flow assembly wasn’t calibrated and charged us $700 for a new one. However, the problem still exists. My husband wonders if it’s a result of bad gasoline…? Please help! Thanks so much in advance for any answers you can provide. Have a nice day.

White smoke is a result of moisture in the combustion chamber. Are you loosing coolant?

I don’t think so. Could it be that the gas has too much moisture in it? I filled up the day before this problem started.

No, if there were enough water in the gas to make smoke, then the car wouldn’t run at all. There’s a good chance this is a head gasket problem. Have somewhere put an exhaust gas sniffer probe over the open radiator cap while the car is running. This will confirm or deny this as the problem.

Check the coolant level carefully. Of course that may not be it, but you want to rule it out. Often the local conditions (humidity temperature rain etc.) and driving styles can cause the smoke.

Are you sure the smoke is not blue?

If it really is white and if you know you are not loosing coolant, then I would suggest taking a small drill bit in a drill and drill a small hole or two in the lowest areas of the exhaust where water might accumulate.