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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHTurbo lag but no turbo!
Leading reported evidence
Replace mass air flow sensor
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
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1
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Performed · outcome unconfirmed · Original poster
I replaced the MAF on the way to work this morning and the surge at 4500rpm has now gone to be replaced with a constant acceleration through out the rev range.
Leading evidence: 'Replace mass air flow sensor' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check should confirm it' (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.
Replace with a constant acceleration through out the rev range
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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 performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
I replaced the MAF on the way to work this morning and the surge at 4500rpm has now gone to be replaced with a constant acceleration through out the rev range.
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 contain suggestions
1
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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.
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Suggestion
You could try cleaning the MAF, but it is usually only a temporary fix.
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.
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Suggestion · Original poster
I've tried resetting the mapping as per other threads but it does not seem to have made any difference.
Discussions that performed work without a confirmed outcome
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.
Performed · outcome unconfirmed · Original poster
I replaced the MAF on the way to work this morning and the surge at 4500rpm has now gone to be replaced with a constant acceleration through out the rev range.
Replace with a constant acceleration through out the rev range
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
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.
Performed · outcome unconfirmed · Original poster
I replaced the MAF on the way to work this morning and the surge at 4500rpm has now gone to be replaced with a constant acceleration through out the rev range.
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.
Porsche Club GB: 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: 20261026T165820Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Over the last couple of days I've noticed a very distinct surge in power when on full throttle just as revs go over 4500 rpm. The power delivery is no longer the smooth linear push that it was. I've tried resetting the mapping as per other threads but it does not seem to have made any difference.
Then tonight I noticed that two warning amber lights (PSM and brake disc) decided to come on under heavy acceleration. Turning the ignition off and back on saw the llights going out.
Does anyone have any thoughts what might be the cause?
Thanks in advance
Mark
ABS and PSM lights coming on under hard accelleration is usually caused by a faulty MAF. This may also explain the odd power surge, as the MAF will not be giving the DME the correct aair flow values. You could try cleaning the MAF, but it is usually only a temporary fix. If the car has done 50,000+ miles, you are living on borrowed time, so I'd replace it if I were you.
A diagnostic check should confirm it.
Thanks Richard that fits with my own line of thinking. So if you don't mind there are some supplementary questions.
The first is where is the best place to get a diagnostic Reader from and how much.
The second is how easy is it to do the MAF oneself and again what sort of cost is one.
Once again thanks
Mark
The BEST DIY diagnostic reader is the Durametric system, which is Porsche-specific, and not only covers the engine control unit, but also most other system like alarm, airbags, aircon, ABS/PSM, instrument cluster, etc, etc. But it's the most expensive. www.durametric.com. Other than that, for your C4, if you only want to read engine codes you could pick up almost any OBD2 hand scanner/code reader from somewhere like fleabay. Bear in mind that some cheap code readers do not show pending codes, only the ones which are triggering a CEL, and I have no idea which one to recommend. Therefore, if you go for a cheapie handheld device, get a scanner, so that you can read the actual values of things like MAF output and O2 sensor outputs. There are also several dozen PC-based scanners on eBay, which aren't too expensive. If you wanted to try a Durametric before you bought one, I have one of those too, and you would be welcome to borrow it for a couple of days. You can download the software from the Durametric site, and then just plug in the cable.
There are 3 different MAFs for 996s. The one for your car is part number 996.606.124.00. The list price of these from Porsche is - sitting down? - £491.33 inc vat. Try Forest Fine or Euro Car Parts as they are much cheaper there.
It's a very easy DIY. You will see the MAF on the top right hand side of the air box, next to where the hose goes off to the throttle body. There are two T20 security Torx screws holding it in. The plug clip is a bit difficult to see on a C4, so I find it easier to undo the screws first, lift out the MAF, and then remove the clip. The security Torx screws have a small pin in the middle, so you need a driver which has a hole up the centre. They are fairly easy to obtain - I bought a set of bits and driver handle for a few quid at a local motor factors.
As always Richard a very detailed and informed response. thank you.
I guess I am reaping the benefits (cough, splutter) of driving a porsche through my wallet.
Mark
It would now appear that the problem has been resolved. I replaced the MAF on the way to work this morning and the surge at 4500rpm has now gone to be replaced with a constant acceleration through out the rev range.
Many thanks Richard for steering me towards Europarts as the really did come up trumps on price. In the end the part cost me less than £160 inc VAT!! A big difference on the OPC price. Swapping it over took less than 5 minutes as well. All I need to do know is think about what Diagnostic tool to buy myself. The Durametric is coming towards the forefront of my thinking though.
Thanks again
Mark
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