Lots of smoke and oil loss
 

My car has been smoking a bit on startup for a week now (not huge billows, just puffs and then stops). Hard to remove the oil cap while engine is running, so I ordered a new air-oil separator for replacement this weekend. For my 120k mile service, I just replaced sparkplugs 2 weeks ago and car has been running otherwise just fine.

Driving home just now and engine starts to flutter. Low oil pressure light flicks on and then goes off. I look in mirrors and there's a puff of smoke, then a light stream. Suddenly huge amounts of smoke (white/grey) billow out the back of the car and I think my car is on fire. Find a place to pull over a block of so later after coasting down the road and shut the engine off.

Push car last block to my garage and pulled out the mini OBD2 chip to see what's wrong. There is a sulfur-like smell, and when I checked the oil, it was very very very low. (I just topped the car off this morning).

Confirmed diagnostic codes:
P0171 System Too Lean
P0300 Random/Multiple Cylinder Misfire Detected
P0306 Cylinder 6 Misfire Detected
P030 Cylinder 3 Misfire Detected

P0002 Fuel Volume Regulator Control Circuit Range/Performance


Thoughts on if my AOS kicked the bucket while I was driving or if this is something more serious? Completely stressed out right now and hoping I'm not suddenly the proud owner of a roller.

It could still very well be the AOS there has been cases when they have completely failed with symptoms of a blown motor. The ingestion of oil and coolant can cause misfire codes.

Just wait till everything cools down first. Check the oil and coolant again and see if you have intermix. What yr is your 996?

2002 C4S. Will check intermix in a couple hours after car is cool. Absolutely crushed at the moment.

2002 is not known for cracked heads so my guess is a bad AOS, if there's no intermix and nothing is dripping out from the engine bottom. Crossing my fingers for you.

Engine is cool. No intermix and nothing dripping out from the engine.

My new AOS should be here tomorrow. Will replace Saturday, followed by an oil change.

Heart is still racing, but a glass of Oban helped calm the nerves somewhat.

Would be good if you can remove the throttle and the T plenum and check thr inside of the intake manifold. If it's the AOS, you should see lots of oil there. Also good to clean that up (can hold a lot) so you don't scare yourself when you see smoke again after the new AOS is installed.

If you haven't changed your coils, I would do that at the same time as part of your 120,000 miles service. Pelican parts have them at under $40 each. Slightly thicker with new type screws. Don't worry, the car will be fine.

Good luck with the fix, im sure you'll sort it all out.

Sounds pretty close to what happened to me when my AOS went. Really scary! And my engine hydrolocked too. But all was fine, so I think you may be happily surprised (if a $1,500+ bill makes you happy!).

Good choice of single malt Oban :D

UPDATE:

AAA sent a truck that was too tall to get into my underground parking garage. Ended up pushing the car to the bottom of the driveway ramp, tow truck backed halfway down and winched my car 1/2 way up the ramp using front tow hook. Truck drove to top of the ramp and winched the car all the way up. Loaded on flatbed and taken down the street to the shop. Shop called and told me next steps.

Step 1: AOS likely dead (replace it). Fix a coolant leak and replace some broken vacuum clamps. Run engine to burn off oil.

Step 2: Replace spark plugs. Maybe replace catalytic converters and O2 sensors (depending on how much oil was ingested into the system).

Step one isn't too expensive, but step two is not cheap. If I need new cats, I'll go aftermarket 200 cell. Very annoyed that I just replaced spark plugs a few weekends ago. All needs to get done as I have emissions due in a couple of weeks. Thanks all for the support.

If your car loses the misfires after the AOS replacement and no error code from the cats/OS, you can skip two completely.

That's the hope!

Well, parts were delayed coming from Porsche and arrived late Friday so shop didn't do any work last week. Shop worked on the car today and apparently the diaphram housing on the new AOS is thicker than the old one, so additional delay in fitting new AOS. Tech finally started the car up at 400p and car is burning off a significant amount of oil. Shop stated it could take over an hour to burn off all the oil. May have to continue to run the engine in the morning if they can't finish tonight.

Sitting here anxiously and hoping cats aren't toast, though I feel they are. Messaged with Fabspeed today and there's a 5 week build time. My emissions test is due by end of month so looks like my options are more limited than I'd like them to be.