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To MAF or not to MAF?


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I'm not sure whether I even have a problem, but here's the deal.

Have had the car (996TT 6sp) for around 5k miles.

I have always found the car difficult to drive slowly. Difficulty matching engine revs so that I don't get a clonk from the transmission. Not impossible but it sure needs a lot of concentration and a very gentle easing out of the clutch. Does not always work. Anyway, very tiring in traffic.

I thought this was normal.

However recently it has been stalling on me. Not daily, or even all that often. Just did 3k miles in 10 days, and it did it 3 or 4 times. In between gears. It simply did not hold idle for the short time that my foot was off the throttle and the clutch was depressed.

Sometimes - very occasionally - when coming off the throttle, clutch depressed, I get revs surging for an instant.

Another thing, when depressing the gas pedal a small amount - I get a response, but say one second later I get a little bit more response. To explain this I could say that if I pressed the throttle 10% of it's travel, I get the appropriate (I think) response, then a second or so later I get some more throttle, as if I had pressed the throttle (say) 12% of it's travel. Like the Egas/DME has woken up and decided that what I really want is a little bit more throttle than I have given it. Or perhaps, it gave me less than ti should have originally, based on pedal position, and it's now giving me what I should have had. A quick note, I opened up the pedal assy and lubed it, feels smooth (wasnt smooth before) so that's not related.

I have the MAF out and will clean it (discovered that contact cleaner is not what I should have bought!) so I will do that but wondered whether I should also be looking elsewhere for a resolution.

At the moment don't have what it takes to pull any codes etc.

Thanks in advance, all.

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I'm not sure whether I even have a problem, but here's the deal.

Have had the car (996TT 6sp) for around 5k miles.

I have always found the car difficult to drive slowly. Difficulty matching engine revs so that I don't get a clonk from the transmission. Not impossible but it sure needs a lot of concentration and a very gentle easing out of the clutch. Does not always work. Anyway, very tiring in traffic.

I thought this was normal.

However recently it has been stalling on me. Not daily, or even all that often. Just did 3k miles in 10 days, and it did it 3 or 4 times. In between gears. It simply did not hold idle for the short time that my foot was off the throttle and the clutch was depressed.

Sometimes - very occasionally - when coming off the throttle, clutch depressed, I get revs surging for an instant.

Another thing, when depressing the gas pedal a small amount - I get a response, but say one second later I get a little bit more response. To explain this I could say that if I pressed the throttle 10% of it's travel, I get the appropriate (I think) response, then a second or so later I get some more throttle, as if I had pressed the throttle (say) 12% of it's travel. Like the Egas/DME has woken up and decided that what I really want is a little bit more throttle than I have given it. Or perhaps, it gave me less than ti should have originally, based on pedal position, and it's now giving me what I should have had. A quick note, I opened up the pedal assy and lubed it, feels smooth (wasnt smooth before) so that's not related.

I have the MAF out and will clean it (discovered that contact cleaner is not what I should have bought!) so I will do that but wondered whether I should also be looking elsewhere for a resolution.

At the moment don't have what it takes to pull any codes etc.

Thanks in advance, all.

At relatively low RPM's the MAF has little impact on how the car would drive. I would strongly suggest before spending money that is potentially unnecessary, you get the car scanned with a Porsche specific system (PIWIS or Durametric) which can tell you a lot of real time parameters concerning mixture control, throttle position, and boost; as well as looking for potential pending codes that may be related. Too many people start swapping out expensive parts unnecessarily simply because they did not do simple diagnostics first. Get the car checked out, it could be something else entirely.......

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Thanks. I won't be spending any money for now, just cleaning out the MAF fwiw.

In a couple of months I should be able to pull some codes but in the meantime was wondering whether the issues I had - those that are real issues - are commonly attributed to any particular part failure.

I read about lack of smoothness in the throttle pedal and sorted that but I do now realise that the pedal itself is linked by cable to the potentiometer (?) so there is still further mechanical connection, wonder whether that could have any significance in the "delayed response" issue.

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Thanks. I won't be spending any money for now, just cleaning out the MAF fwiw.

In a couple of months I should be able to pull some codes but in the meantime was wondering whether the issues I had - those that are real issues - are commonly attributed to any particular part failure.

I read about lack of smoothness in the throttle pedal and sorted that but I do now realise that the pedal itself is linked by cable to the potentiometer (?) so there is still further mechanical connection, wonder whether that could have any significance in the "delayed response" issue.

Problem is that without specific codes, you have to rely on real time data readings (fuel trims, boost data, throttle position data, etc.) to tell you what is happening when it occurs. This is particularly important on turbo cars because increased level of complications in the system. Something like the Durametric system can supply you with real time throttle position data to tell you what your e-gas system is doing at any moment in time. Without this information, you are reduced to guessing what is happening.

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