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My 99 996 idles up and down if I turn the automatic climate control on and off. The car idles much smoother with the climate control on. When it is off it idles rough and trips the maf sensor. It will idle at about 900rpm with the automatic climate on and about 700 and running rough with it off. Any thoughts????? :(

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Have you tried cleaning the MAF?

I just tried that and it seemed to help. I did disconnect the battery for a few minutes and the CE light is off now. I am not sure it will come back on or not. I did cycle the ignition 10 times and the light did not come back on. It does however seem to run a little rough with the Climate control off, but better. Any other thoughts?

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On the older Motronics 5.4 (or something like that), it will take 2 - 3 full cycles to completely settle the idle down. At first, the idle will be a little high and be slow to go down when coming to a stop. After the 3rd time your car is started after sitting for a few hours, all should be back to normal. You might also remove the idle control valve on the left side of the throttlebody and spray the inside valve with carb cleaner. It gets sticky sometimes.

If you find that it improves things, you can clean the MAF again and again without damagiing it.

Edited by 1999Porsche911
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...  You might also remove the idle control valve on the left side of the throttlebody and spray the inside valve with carb cleaner.  It gets sticky sometimes.

I have a similar problem, do you have a picture of the valve you are talking about, and maybe some step by step comments? I'd like to try it, but would like some guidance.


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