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Idle issue
Never had a problem with this before, just wondering if it's due to outside temp(40 degrees) Start the car and it really searches for an idle speed and stalls when starting in the morning. Seems better when warmed up.
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PCA National Instructor 93 RS America (some things done to it....)(gone) 85 Carrera (gone) 06 BMW M5 (gone) "If you ain't first, your last" |
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03-18-2010, 04:57 AM
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I'd almost be prepared to put money on the fact that it's an oil contaminated ISV. The effect of cold oil makes the slider reluctant to move so the engine gets insufficient air on idle - so it dies. Once things warm up a bit, the oil thins and the slider can move quicker and the idle stabilises better.
There's every chance I may be wrong, but cleaning the ISV with some carb cleaner would be a good cheap move and it may solve the problem. Regards Dave |
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03-18-2010, 05:42 AM
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Pardon my ignorance, ISV? Would be up to do myself, just need to know what to do?
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03-18-2010, 06:06 AM
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The ISV is the Idle Stabilisation Valve which sits right at the top of the induction above the engine. It's an electrically operated valve controlled by the DME which allows a controlled volume of air to pass into the induction system in order to maintain the idle speed.
The DME is set up to match the ISV by performing what is called a "System Adaptation" with the Bosch tester. Anything that alters the characteristics of the ISV (like oil contamination) will have an impact on the idle speed. A sluggish response will mean the engine will not get sufficient air to maintain the idle and it will stall. If the ISV doesn't respond quickly enough in a start situation, the engine will not start. This is why you should not touch the accelerator when you start the engine as it prevents the DME from controlling the ISV. There is a DIY (admittedly for a 993) here, but the basics are virtually identical for the 964. Hope that explains it. Regards Dave Last edited by computamedic; 03-18-2010 at 07:45 AM.. |
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03-18-2010, 07:40 AM
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Found the article and it's a very straightforward operation. I'll take care of it today and hopefully that will do the trick. Thanks for the insight!
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03-18-2010, 09:06 AM
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Thanks for the help. Real easy to do. Only thing I changed were the hose clamps. The stock ones are a little difficult to remove. Just added screw in type.
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PCA National Instructor 93 RS America (some things done to it....)(gone) 85 Carrera (gone) 06 BMW M5 (gone) "If you ain't first, your last" |
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03-19-2010, 08:06 AM
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