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BMW 3-Series (E90 E92) Forum
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Car stalls but not with MAF unplugged
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10-16-2018, 11:00 PM | #1 |
Captain
124
Rep 654
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Car stalls but not with MAF unplugged
I had to replace the starter motor.
Now the car would start, but stalls right afterwards. No codes. When I unplug MAF sensor, it holds idle, though rough. Is this for sure a bad MAF sensor? Or this could be due to other vacuum leak created from above ? Thanks in advance |
10-19-2018, 08:43 AM | #2 |
Second Lieutenant
124
Rep 287
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Drives: 2009 328i
Join Date: Dec 2011
Location: Harrisburg, PA
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Vacuum leak. That's a classic symptom. Engine is getting unmetered air from somewhere, and because the MAF is plugged in and providing (an incorrect) signal, the DME doesn't compensate with more fuel. I chased the same thing on my old X3 until I found a wrecked front crank seal.
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10-20-2018, 09:29 AM | #4 |
General
17226
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I agree, there is a vacuum leak somewhere. There should be a SES light now too (for the missing MAF signal). The engine will idle without the MAF plugged in because the ECU is not getting a MAF signal and goes into a predetermined map to keep the engine running as best it can. Check for a PCV hose being cracked or broken (common problem when removing the intake), or you left a hose off the intake when reinstalling it. Or an intake manifold gasket didn't seat correctly and is leaking.
My 2 cents.
__________________
A manual transmission can be set to "comfort", "sport", and "track" modes simply by the technique and speed at which you shift it; it doesn't need "modes", modes are for manumatics that try to behave like a real 3-pedal manual transmission. If you can money-shift it, it's a manual transmission. "Yeah, but NO ONE puts an automatic trans shift knob on a manual transmission."
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10-21-2018, 01:49 PM | #5 |
Lieutenant
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Did you plug in the fuel tank vent valve that goes behind the throttle body?
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