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Steve, BMW Expert
Category: BMW
Satisfied Customers: 25231
Experience:  BMW Expert
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When I plug in the air flow the engine runs badly and won't

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When I plug in the air flow the engine runs badly and won't tick overe

what has been tested other than un plugging the sensor?

what codes are present?

Customer: replied 3 years ago.
Has no fault codes the throttle response is poor when u want to pull away and I noticed it hisses from inside inlet manifold
I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.
It is possible that the maf is bad, but if you hear a noise, I suspect it may be a failed crankcase vent valve or intake air leak that is causing a lean mixture. When you unplug the maf, the car automatically richens the mix which can compensate for the leak.
I would start by checking for air leaks or a failed crankcase vent valve - or try swapping in a known good maf.
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.
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