Smoke once in a while when starting
 

Twice in the past 2 thousand miles, the car has smoked, surprising amount of smoke, on start up.

The smoke is gray white in color and doesn't smell sweet or like burning oil. It smells like there is a lot of carbon as if the car was running super rich.

Both times it was after I started the car and backed it out of the garage and shut it right off. Then went back a bit later and started it to go somewhere. That's when it smoked. Any ideas?

It's probably done it a few more times that you haven't noticed. It's a normal occurance every 20 or so startups. Any more than that, or if it occurs while running, say at stop lights, could mean your AOS is on its way out.

Very normal occurrence. As mentioned, mine is about every 20 starts. Small vapor cloud. 3-5 seconds.

Are you running the proper oil level?
Are you running the proper oil viscosity?
Mileage?

I suspect your AOS is on the way out. Not major. This is a maintenance item.

A "puff" of smoke on occasion can be normal. You said yours is showing a "surprising amount", so this sounds less normal.

Here is a theory.

When I let my car "idle down" I would notice it smoking the next time it was started.

When I shut it off once in the garage, no smoke on next start.

May have to do with the angle of the pistons.

I think there is a test too, to see if the AOS is failing or has failed. Idle the engine, remove the oil cap, put your hand over the opening, and your should feel suction. Right?

Put your hand over the opening? Man, have I been doing it wrong!

I have no idea what you're saying, but JFP in PA has covered this tip before. Maybe I am miss quoting it, though.

You should feel just the slightest amount of suction, and you will hear the idle change as you put your hand on and off the intake tube.

If you feel a lot of suction or have trouble getting the cap off, then its likely the AOS.

^Thank you, San Rensho.:)

When the AOS goes bad what color is the smoke typically? 29,000 miles.

there's this...

Porsche Boxster S 986 White Smoke on Startup - YouTube

Ok, so I did the AOS test and it passed. So I'm not going to worry about it and go with the every 20 start smoke theory.

If you're switching out the AOS in the future, look out for the updated version. I believe the first version is still floating around.

a guy mentioned this on another forum, he said it will be the carbon cannister that needs changing. hope this helps.