Doug H

Seems like oil is low and engine increased in rpms when I removed oil cap? Is this AOS on a 997.2?

definitely pressure on oil cap when running.

Steph1

Strictly start up cause someone else started the car while you observed, or you got out of the car after starting it and it smoked for a few seconds after that??

Doug H

just after one start up where car sat for maybe an hour and a half. Nothing since then.

Tcc1999

I hate saying, "Do a Search", because it is very unhelpful. That said, I recall that there have been many threads on this topic and one particular poster, "Macster", always seems to have had pretty good information on this topic. So, if you do a search on smoke oil, start up , etc. and use Macster as the Poster, you will get several hits. I just did this and there were way too many to parse through. Best of luck. Also, my GTS also does this occasionally (once every several months when I used to drive it regularly and ever since I got it in 2011) so I am inclined to go with the simple explanation that it is just excess oil seepage in the exhaust system that is being burned off.

Bruce In Philly

You must check the vacuum pressure. Read this thread:

https://rennlist.com/forums/997-foru...tml?styleid=13

Peace
Bruce in Philly

Steph1

Quote from Macster of the said thread:

A brief bit of smoking at cold engine start can be normal if it is brief, the CEL remains off, and the engine doesn't manifest any untoward behavior: rough/erratic idle; for example.

The techs tell me they encounter this brief smoking at cold start all the time with used and even new cars on the dealer lot and the above is how the deal with the event.

In milder weather the smoke is indeed smoke, oil smoke. It comes from the AOS and its inability to prevent some oil vapor from passing through. This oil vapor enters the intake and because the heavier oil vapor particles can't make the sudden/sharp 90 degree turn impacts the intake wall opposite where the hose from the AOS connects to the intake. If the engine is shut off this oil warms up as the intake warms up from the heat soaking and the oil then drains down on top of the intake valves if the intake valves are closed, or runs into the combustion chamber/cylinder if the valves are open.

Upon a cold start, because the engine and exhaust is cold, the oil doesn't burn completely and a bit of smoking is what you see.

In colder weather the smoke can be accompanied by water vapor or because usually the oll smoking is infrequent the water vapor is all there is.

Oil smoke hangs together in even a breeze as it is carried away from the car. Water vapor dissipates even if there is no breeze.

Water vapor is normal too. It is a byproduct of combustion. When the engine/exhaust is hot unless it is very cold one doesn't see the water vapor.

Depending upon the ambient temperature and humidity the engine can emit visible water vapor for a few minutes or more.

Just a bit of some info FYI.

In the case of your car the smoking is as you suspect not normal by all I know and all the experience I have with this. (After over 310K miles in my Boxster and 3 replacement AOS's, 155K miles in my 996 Turbo, I've seen exhaust smoke and water vapor or a combination a good number of times.)

It is not fuel burning off.

There's not anything you can do about this other than note under what conditions the smoking occurs and relay this to the service department.

Be prepared to when you take the car in that you could get "they all do that". Ask for a demo of several cars. Before this comes up, if it comes up, look for a car that has clean (no rust) brakes. This suggests the car was driven a bit before it was parked and not too long ago.

Stress that the smoking has caused you to lose all enjoyment of the car because the smoking is not normal and you are concerned about the car suffering a breakdown and in this event jeopardizing your safety as a breakdown on a busy road/highway or freeway puts you at considerable risk.

You have to be prepared to leave the car. If the dealer can convince you to continue to drive the car this signals he can put you off.

So leave the car with it clearly understood -- wriite it on the work order if the SA doesn't and be sure it is on the copy the dealer keeps and the copy you keep -- the cause of the smoking must be determined and addressed to your satisfaction

Doug H

Oil level dropped and idle seems a little high.

anewman

(if 997.2) Not sure how you were parked, but if car was parked at an angle (with right side lower than driver side, or rear lower than front), AND if the engine level is full, this can often cause smoke at startup - harmless. Disregard if you were parked on perfectly flat surface.

Wayne Smith

This. Add sloped to either side for smoke and front to back level doesn't matter much.

I have never burned oil (7.5 quarts out, 7.5 quarts in at each 5K mile oil change from 35K to 130K miles with no additions in between). But if I park on a side slope (and only then) I can suffer significant smoking at start up that can last for a minute of idling.

Everything I've read and heard indicates this is normal as oil sprayed ol below the piston skirt will work it's way past the piston rings and into the combustion chamber on one side or the other ... A side affect of a flat motor (problem shared by Subaru for instance).

Doug H

This is at the end of a driveway at a weird angle. Leans a little forward and to the right as the house is built at the top of a big hill.

I park here every once and a while as it is an investment property. Most of the time, I park in the street when I pull up. Seems like I recall having smoked one other time when parking here and wondering if it was steam or smoke. Today was a clear warm day so it was definitely white smoke.

It has been 5,711 miles since last oil change and I was a quart low. I went by Porsche dealership and my buddy looked it over, jump in and we drove it around. He said no big deal, just seepage.

Khloesdad

If theres one thing I hate about these cars is there no oil dipstick. I hate having to rely completely on sensors to tell me everything.

Oneday997

Mine will kick out some smoke if it hasn’t warmed up to operating temperature before I park it. If I go for a drive, get it up to temp and park it, all is well. A couple weekends ago I went for a drive, parked in the driveway and washed it and then moved it to the garage. Sure enough, smoke on the next start up. Don’t know why, but doesn’t seem to hurt anything. Car runs great.

Jaws1

I had a 991.2 C2 for a couple of years and it would blow smoke on a cold start on occasion. My current 997.2, previous 997.2 and previous 997.1 would all do it too. A feature of a horizontally opposed engine.

Hindsight2010

I have a 2009 with 45k miles on it and it. I don't recall ever having smoke on startup except when the car has been parked several days without being started. If parked more than a couple days, I get smoke, not water vapor. The longer the car sits, the bigger the cloud.

ADias

It may help if when you turn off the engine for the day you park on a flat spot and let the engine idle for a bit - 30 sec or so and then shut it off.