Originally Posted by blue2000s
From what I can tell from my own experience and what I've gathered from other comments, this almost always is the source of the infamous puff at start-up.
Mine's exactly the same... the car must be started up from cold, ran for just a short while (moving out of driveway to wash car). If it sits there at least overnight (even if combined with another short drive back up the driveway)... the next start will be a smokey one.
I'd replaced my 10 yr old aos as part of preventive mantenance and it makes no difference to the abovementioned "recipe" for a smokey start.
After every long drive, the car starts up from cold without the smokey start....
My car is totally predictable when it comes to smokey cold starts. The amount of smoke is quite alarming (and embarrassing...) - one large puff, enough to fill my driveway with blue smoke. My neighbours have long stopped running over to warn me about the smoke... ha ha..