BMW E34 mass air flow sensor faults and cleaning
518iM5
How is the E34 mass air flow sensor cleaned?
Remove the sensor and spray air sensor cleaner (e.g. CRC Air Sensor Cleaner) onto the sensor and its flap. Check the sensor wire before cleaning. Cleaning can improve throttle response, but the help may be only temporary.
What can damage the mass air flow sensor?
An oiled air filter ruins the sensor, so one should not be used. The sensor reading can also dip at half throttle when the sensor is old; a new sensor improved running and throttle response. An ignition fault can disturb the sensor's signal.
How do I know if the fault is in the mass air flow sensor?
The sensor's operation can be verified with an oscilloscope. A quick test is to unplug the sensor connector for a moment: if the engine runs better, the fault may be a vacuum leak or the sensor. It is not a fix. The leak can be, for example, in the intake manifold gasket.
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