Air Flow Meter/Sensor: Description and Operation

Mass Air Flow (MAF) Sensor:

PURPOSE
The Mass Air Flow (MAF) sensor uses a hot wire sensing element to measure the amount of air entering the engine.






OPERATION
Air passing over the hot wire causes it to cool. This hot wire is maintained at 200 degrees C (392 degrees F) above the ambient air temperature as measured by a constant cold wire.

The current required to maintain the temperature of the hot wire is proportional to the air intake mass. The MAF sensor then outputs an analog voltage signal to the Powertrain Control Module (PCM) proportional to the intake air mass.

The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. This input is also used in determining transmission Electronic Pressure Control (EPC), shift and torque converter clutch scheduling.