1999 BMW 540i



April, 5, 2010 AT 12:03 PM

Engine Performance problem
1999 BMW 540i V8 Two Wheel Drive Automatic 100, 00 miles

I have an idle question about my 540 bmw the car runs good but the idle is low. I have checked for vac. Leaks and I want to look at the iac motor and valve but I turned the ac on and when the compressor is on it idles where it should " odd" so now its real strange. Do you have any ideas as to what could be the problem. Thanks for any help you can give


2 Answers


Dr. Hagerty

April, 30, 2010 AT 12:20 AM

The idle is too low? What is too low?



May, 26, 2010 AT 1:45 PM

The idle is sitting at 500 rpm whitch is the line, but when I turn on the ac compressor it will idle at around 750 rpm, with the ac compressor on it runs better with it off you feel the down shift to first gear and when it down shifts the rpm drops below 500 for a split sec. And comes back up. I took it to a mechanic and he cleaned terminals and it idled at 750 for a day then down again i'm wondering if it is ilde air vaulve or motor or something

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