Slight hesitation, temp fixed by resetting computer

[grahamtwatson]

My 02 996 has a slight hesitation at low revs when accelerating. It's not serious but it is annoying. The odd thing is that if I reset the computer by leaving the battery disconnected for an hour or so, the hesitation vanishes, the car feels a little more lively, and the fuel consumption improves a little (from 17 to 19 on my usual routine). Over a couple of weeks, the hestitation returns and the fuel consumption slowly increases.

I'm wondering if the computer is "getting it wrong" as it trys to relearn after the reset???

I've cleaned the throttle body thoroughly and also the MAF using the correct cleaners, without any effect. I also took the car to Schucks and got them to read the codes, but there weren't any - although I'm wondering if their reader would pick up every code.

Help?

[RFM]

If you disconnect the battery, the DME will reset not only the memory but the actual values also, that's why the engine runs better if the parameters are not too much out of the permitted values. Let check the DME "actual values" with a PIWIS or similar diagnostic tool when the car is suffering with hesitations, even with the CEL out (no fault codes found)

[grahamtwatson]

If you disconnect the battery, the DME will reset not only the memory but the actual values also, that's why the engine runs better if the parameters are not too much out of the permitted values. Let check the DME "actual values" with a PIWIS or similar diagnostic tool when the car is suffering with hesitations, even with the CEL out (no fault codes found)

I think I know what the problem is now - I got a local independent garage to put his Durametric on my machine, and although there were no codes, the car did think that the air intake temperature was 54 degrees Centigrade, which is about 130 degrees Fahrenheit. On a rainy day in Seattle, I don't think so!

I gave the MAF a REALLy good cleaning, and it's marginally better, but I think it's basically due to be replaced.

Before I spend unbelievably large amounts of money on a tiny piece of plastic and metal, does anyone want to tell me what they think will happen as a result of the car thinking it's 130 degrees when it's really about 55? My guess is that it will decide the air is thinner and put less fuel in, hence leaning out the mix. Am I right?