6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHSelf Healing - MAF
Reported or suspected cause
perfectly good maf
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that report identifying a cause
1
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Reported cause
It was failing to detect a leaking cap that had me misdiagnose a MAF and replace what proved to be a perfectly good MAF.
Leading evidence: 'perfectly good maf' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'perfectly good maf' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Adjust coolant level properly' (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.
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed · Original poster
I hosed down the left side of the engine (around the coolant overflow) & adjusted the coolant level properly.
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
I did a recent oil change & checked the oil cap several times.
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Discussions that contain suggestions
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While in all my several hundred miles of driving (282K miles on the Boxster, 123K miles on the Turbo) the 2 times I've cleaned the MAF on the Boxster I've never found the MAF to be at all dirty.
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 suspect a cause
1
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Suggestion
A dirty air filter restricts the necessary volume of clean air from reaching the engine which affects the MAF and the emission control systems of the car; reducing air flow and causing a too rich air-fuel mixture which can foul the spark plugs.
While in all my several hundred miles of driving (282K miles on the Boxster, 123K miles on the Turbo) the 2 times I've cleaned the MAF on the Boxster I've never found the MAF to be at all dirty.
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Suggestion
Be aware, you have to be sure you get the TB installed again with no air leaks or you replace the AOS and the symptoms are still present and then you are scratching your head as to where the problem might be.
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.
6 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.
1 acknowledgements have no verified action link; they do not establish a repair result.
So my car was having symptoms of a failed MAF. Wandering (warm) idle, rough (cold) idle, and check engine light with 2 O2 sensor codes. I tried cleaning the MAF with no improvement. I ordered a new MAF. The day it arrived, my symptoms disappeared. Check engine light off, runs perfect. Lucky me?
What year is your 996 ?
A review of your service history is a good starting place. Did you have a recent full temp decent length drive time ? Recent full new gasoline ? How many miles ? Ever a fuel filter change if it's a early car ?
Have you serviced your air filer ? Symptoms of a dirty air filter a noticeable decrease in gas mileage also potential ignition problems caused by fouled spark plugs. A dirty air filter restricts the necessary volume of clean air from reaching the engine which affects the MAF and the emission control systems of the car; reducing air flow and causing a too rich air-fuel mixture which can foul the spark plugs. Fouled spark plugs can then create a engine miss, rough idle cold and warm In addition, that too rich fuel mixture increases engine deposits creating MAF errors which may even cause the CEL
Usually cars don't fix themselves.
No. In fact, just the opposite.
The symptoms are probably not MAF related.
The symptoms read like an intake air leak. First to be considered is the AOS.
Next is the oil filler tube cap. These can leak and cause all sorts of problems.
Post the codes.
Thanks for the replies. I had the codes written down but... I'm guessing here p1128 & p1130? I did a recent oil change & checked the oil cap several times. I also recently changed the water pump & I think I overfilled the coolant level because it overflowed on me. I hosed down the left side of the engine (around the coolant overflow) & adjusted the coolant level properly. Driveability problems started around the same time as these maintenance items were performed. Car has low 70K miles and is a 2001 model. Clean air filter. I do think my AOS is failing though; not looking forward that project.
Check the oil tube filler cap with the engine up to temperature and with the engine idling. Try to move the cap about on the tube and listen for any air leaking past the cap or note if the engine reacts. It was failing to detect a leaking cap that had me misdiagnose a MAF and replace what proved to be a perfectly good MAF. (Actually, I just couldn't hear the damn leak. A co-worker at the car heard it for me.)
Erase the codes. Drive the car. If the CEL comes back on read the codes and post.
If at any time the engine starts hesitating or develops an erratic (hunting) idle, smokes at startup but doesn't stop after a moment or two, or just acts up, shut 'er down.
If you are up to it remove the throttle body. While in all my several hundred miles of driving (282K miles on the Boxster, 123K miles on the Turbo) the 2 times I've cleaned the MAF on the Boxster I've never found the MAF to be at all dirty. However, when the first AOS was acting up the throttle body was quite dirty, oily, due to its proximity to the hose from the AOS to the intake, this hose connected right behind the AOS.
If you remove the TB and find it dirty/oily that's a good sign the AOS is going out. Be aware, you have to be sure you get the TB installed again with no air leaks or you replace the AOS and the symptoms are still present and then you are scratching your head as to where the problem might be.
Really, if you suspect the AOS just replace it. While you may not be looking forward to the job, do it at your convenience, not when the thing finally gets so bad you have to do it.
Running rough could have been caused by washing the engine down if the coil packs are cracked. This is one of the few "self-healing" issues I can imagine, and it's consistent with your timeline.
This is a source reference. Confirm exact model applicability in the original material.
