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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHChanged my air filter, removed Hemholtz, and WTF smoke - help
Reported or suspected cause
air oil separator
Reported cause
No successful repair reported for this finding.
1
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0
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0
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1
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Reported cause · Original poster
Just because I hate it when threads are not updated - it was the AOS.
Changed my air filter, removed Hemholtz, and WTF smoke - help
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Leading evidence: 'air oil separator' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'air oil separator' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check dash' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
Realzing it was the AOS I tried to drive the 10 miles back to the dealer but only made it a mile before the AOS got so bad that not only was the engine smoking heavily all the time it was running rough.
Changed my air filter, removed Hemholtz, and WTF smoke - help
around 700 miles
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
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Reported cause
The first sign of a problem was around 700 miles from home and a few more times as I drove nearly 2K miles.
Changed my air filter, removed Hemholtz, and WTF smoke - help
Check dash
Performed · outcome unconfirmed
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0
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0
Unsuccessful attempts
1
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Performed · outcome unconfirmed
At first suspecting a coolant leak I checked the dash for any signs of trouble.
Changed my air filter, removed Hemholtz, and WTF smoke - help
Check rear view mirror and saw a cloud
Performed · outcome unconfirmed
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Performed · outcome unconfirmed
The last one in particular the engine was fine, no CEL, no symptoms of any pending issue and after taking off from a stop light I checked the rear view mirror and saw a cloud.
Changed my air filter, removed Hemholtz, and WTF smoke - help
Check rear view mirror and saw a cloud
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Performed · outcome unconfirmed
The last one in particular the engine was fine, no CEL, no symptoms of any pending issue and after taking off from a stop light I checked the rear view mirror and saw a cloud.
Changed my air filter, removed Hemholtz, and WTF smoke - help
Use some random cleaner
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Suggestion · Original poster
While changing the air filter, I wiped out the inside of the air box to clean it and used some random cleaner from the kitchen - and I thought I avoided spraying the MAF, but maybe not.
Changed my air filter, removed Hemholtz, and WTF smoke - help
aos i tried
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
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Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
Realzing it was the AOS I tried to drive the 10 miles back to the dealer but only made it a mile before the AOS got so bad that not only was the engine smoking heavily all the time it was running rough.
Changed my air filter, removed Hemholtz, and WTF smoke - help
Coverage and how to read this overview
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
18 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261026T033439Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Sorry, had to make a catchy title
I changed my air filter a couple of days ago with a brand new Mann filter. The old filter was probably in there for 10K too long. Dirty but not awful. I also removed the Hemholtz resonator and sealed up the hole in the air box (rubber intake boot was previously sealed when I capped the air box). They are good and sealed.
On start up the car's idle was terrible and lumpy. I drove it around a bit and noticed heavy exhaust smoke after about three miles. Not steam, not oil - I suppose the mix is bad and its excess gas. I reset the ECU and drove it around a few more miles. It seemed to go away. All good.
Driving home from work today it started again with a vengeance. Even worse. Like enormous, billowing clouds trailing me for an 1/8th of a mile after slowing down and accelerating. Tried to reset the ECU again. Tried to fiddle with the intake boot (squeeze/pull etc) looking for vac leaks. No dice. Actually got much worse.
Oil is OK, level is unchanged. Coolant looks OK. Oil pressure and coolant temp are normal.
Did I somehow kill the MAF? Would the MAF even cause THAT MUCH smoke? It's like James Bond levels. While changing the air filter, I wiped out the inside of the air box to clean it and used some random cleaner from the kitchen - and I thought I avoided spraying the MAF, but maybe not.
I appreciate your educated guesses. I just dropped a couple grand in maintenance so I'm not so pscyhed about this, and I don't dare drive it in this state.
Dave
You know it's funny, I've been sitting here reading about AOS failures...but why on EARTH would be it precisely coincidental with an air filter change? The oil cap is moderately difficult to turn and the engine hunts and drops RPM when I remove it at idle.
I also had the car in the shop a week ago to have the plugs/tubes/coilpacks changed. Coincidence? Could they have borked something?
Thanks, 3.4 in my old girl.
Just for giggles I cleaned the MAF, re-sealed the resonator exit plug, cleaned the TB...
and still the same.
Calling a flatbed in the morning.
I generally don't believe in coincidences but they do happen. I replaced the bad micro switch on the passenger door handle. When I finished the job and went to pull my car back into the garage, I noticed that my drivers door latch micro switch had stopped working. What are the odds?
To remove the idea of coincidence in your mind, have you tried putting the other air filter (I know it's old and dirty) and putting the air box back to its original state? Aos wouldn't cause a lumpy idle or billowing smoke (from what I've read here) just a brief moment of smoke at start up.
Reads like AOS. A bad MAF could result in a number of sympotms but smoking is not one of them.
In some AOS fialure stages the oil filler tube cap can be hard to imoossible to remove against the bad AOS low pressure in the crankcase vs. atmospheric pressure but even if the cap is not hard or impossible to remove this doesn't necessarily let the AOS off the hook.
Persistent smoking upon start up and after is a pretty good sign of a bad AOS. The 3 bad AOS's on my Boxster manifested that sign. The last one in particular the engine was fine, no CEL, no symptoms of any pending issue and after taking off from a stop light I checked the rear view mirror and saw a cloud. At first suspecting a coolant leak I checked the dash for any signs of trouble. There was none. Realzing it was the AOS I tried to drive the 10 miles back to the dealer but only made it a mile before the AOS got so bad that not only was the engine smoking heavily all the time it was running rough. The car covered the rest of the distance to the dealer on the back of a flat bed tow truck.
The AOS failing is probably just a coincidence. I do not recall the last time, but the time before I had just had teh car servcied before heading out on a road trip and had only had the car back from the shop a few days. The AOS was giving hints of a pending problem while I was on the road but I mis-diagnosed the symptom (CEL) as a bad MAF. The first sign of a problem was around 700 miles from home and a few more times as I drove nearly 2K miles. Afterwards I was at my final destination spent the night in a hotel room. The next day at first start the engine emitted copious amounts of oil smoke.
*edited* Good to know it's just the AOS.
Since the transmission is coming off...any plans to address any other PM items?
Where did the $1500 number come from? I'm assuming labor - I have seen posts on other sites from 996 owners who were charged 20 hours labor to replace an AOS. 3 hours for a non-drop, 7-10 hours maybe for the more involved procedure...
Just because I hate it when threads are not updated - it was the AOS.
83pCz5I.jpg
And there is the torn diaphragm. I have a tip so the easiest way to do this was for the shop to drop the drivetrain. Took them five minutes to swap the AOS with a new one. Dammit.
AOS is one of those parts where if it were in the front of the engine it would be a piece of cake. But dropping the engine and have to get to it is such a pain. I did it myself and am proud that I did but it was a tedious job that I hope I don't have to do again any time soon.
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