exhaust smoke upon start - up on 2002 Nissan Pathfinder

Upon start-up about 50% of the time a large amount of white smoke comes out of the exhaust.
After driving about 1/2 - 3/4 of a mile the smoke is is gone.
I've noticed it usually happens when the engine is cold.

Had it tested twice, and unfortunately it did not smoke when tested. Any ideas?

2 answers
Pull your plugs and look for oil or water. If it's oil it could be leaking in from the valve guides, water a head gasket or crack in the head or block.
Sounds like a head gasket. As the vehicle warms up the leak is sealed by the expanding engine parts.