jerry wentworth

Car has 130,000 miles and has been running fine until I went for an "Italiian tuneup"...full throttle up hill. Massive smoke poured out the back. I supected AOS failure. New ASO and another tune up (same hill), same result...massive smoke.
Bottom line is that the car runs fine and seems to have normal power until I floor it, then the smoke covers the landscape and power drops off badly. CEL of course... "SAI insuficient flow" which I've had for years and P0139 Aging of Oxygen Sensor After Catalytic Converter (Cylinders 1 - 3) which is new. The 02 sensors have never been replaced (I know, my bad). I would be very appreciative to hear any thoughts from the group about what's happening here and how I might go about diagnosing/confirming
the cause. Thanks for your help.

Gasngo

What color is the smoke ? What model what year?

jerry wentworth

2003 986 S and smoke is not white

pilot4fn

Could it be that you have too much oil? Try with dipstick marks only half of oil, then this same 'Italian tuneup'. The electronic dash oil cauge could be showig wrong.

Dr. 914

usually the air oil separator has failed

Bush Pilot

Jerry is saying that the smoke is not white so it's not oil. If it's not oil then it has to be gas and that shows as black smoke. Sounds like the engine is receiving too much fuel under a load. I'm not sure what would cause that.

Bush Pilot

As a start I would trust the fault code and replace the oxygen sensor.

Gasngo

Any further input Jerry just curious.

jerry wentworth

Yes, I have more to add to the discussion but first let me correct the comment I made about the color of the smoke. When I said it was "not white" I was thinking in terms of "blown head gasket white" which it clearly was not. However, having an opportunity to see the smoke cloud without sunglasses convinced me that I've misdirected the discussion. The smoke is clearly not the black smoke one would expect from a fuel problem and I apologise for this misstatement of fact. That said, I am now convinced that the problem is definitely related to oil in the induction system and last night I dismantled the plenum tubes and found lots of oil in the tubes and runners. After a careful cleaning and re-assembly I took the car for a 10 minute run which include twisty rural and freeway speeds.
Performance was normal until I took on the devil hill under hard acceleration and the massive smoke cloud appeared once again. Bottom line...I'm convinced that for whatever reason a ton of oil is finding its way into the air induction system. And. most importantly, the problem only shows up under hard acceleration going up hill. The AOS is new and is the second one i've installed in the last few weeks because i thought (wrongly) that the first one was defective. I've seen several posts on the web about similar problems developing under high G left turns on tracked 911's that seem to be related to the scavenger pumps but have seen nothing about hard acceleration going up hill. Is it possible that no one else has ever had this problem?
I'm baffled and would love to hear any thoughts from the group.

JFP in PA

Two questions:
1. Is the new AOS unit a Porsche part, or aftermarket? Most aftermarket units we have seen are junk, right out of the box.

2. Where is your oil level? For years, everyone from Porsche to LN Engineering have recommended running the oil fill 1/2 quart LOW to reduce AOS failures and occasional smoking.

Gasngo

I like JFPs comments and ya sounds like you are on to something regarding the oil being burned. I dont know what the breathing system looks like is there a vent off a cam cover or somewhere near or crankcase. Ill read up on it but many years back we had a customer with a 500 SEL Mercedes that would complain about smoke on hard accel. We chased it and chased it no obvious problems not to mention a much more simple system So we sent the shop rat to ride home with the customer and also let the customer try to duplicate the problem. Well the shop rat came back white as a sheet. The owner [Mexican national] drove that sedan like a IMSA GTP he would accelerate as hard as he could up hill and down shift going into corners which sent the engine vacuum through the roof. Once he would accel again the intake breather was full of oil. What was happening is the timing chain/gear flung oil up into the baffle area of the valve cover and under heavy vacuum oil got drawn went into the intake. So pulled the valve cover and found a 1/4 gap between to points filled it with sealer and no more problems.
Does not sound like vacuum on your end but think along those lines what components are all included in the evap system or what ever they call it. BMWs had negative crankcase ventilation if I remember does the m96 have the same? Keep us posted.

jerry wentworth

Oil is almost a quart low and here's the dope on the AOS purchased from Pelican Parts :

Part #: 996-107-026-02-OEM Oil Separator(2003 Porsche Boxster S Convertible)(m)

I believe this is a genuine Porsche part.

Gasngo

I did not read every word but this is pretty decent info and ought to help you with diagnosis. Check it out.
https://www.pelicanparts.com/techart..._Separator.htm

Bush Pilot

I can envision the hill coupled with excess intake could cause the pooling oil in your intake to flow to the cylinders.

ZuffenZeus

Watch this...