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Old 05-16-2026, 09:00 AM
Effduration Effduration is offline
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Quote:
Originally Posted by Meestahbig View Post
I don't see any signs of a vacuum leak. Shop didn't even bother to do the test and brushed it off after asking multiple times. I have suction at the oil fill cap. Nothing crazy, just right. I spoke tested it and didn't see anything. Fuel mileage is okay, so maybe it's a small leak somewhere near the Idle Air Control Valve.
Do you have any way of measuring fuel trims while driving with a warm engine?

Long term fuel trims above +5% would tell you if you have a vac leak..

I use the OBDFUSION phone app in conjunction with an OBD2 WiFi reader

Also, the idle speed control valve rarely fails altogether.. it does stick and require cleaning now and then… A used Genuine BMW ISCV is likely better than a new aftermarket part.
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