Air Flow Meter/Sensor: Description and Operation

Mass Air Flow Sensor:

PURPOSE
To provide the Powertrain Control Module with an electronic (input) signal which corresponds to changes in intake air flow to the engine.

OPERATION
The Mass Air Flow (MAF) sensor, located between the air filter and the throttle body, measures the mass of the air entering the engine.
The MAF sensor operates on the principle that if a mass is maintained at a constant temperature above the ambient environment, then the thermal loss is proportional to the mass flow of the cooling medium it is subjected to.
The electronic module of the MAF sensor heats a wire element to (200°C) 392°F above ambient temperature. As air passes through the sensor, the air cools the wire element. The MAF sensor supplies more power to the wire to keep it at a constant temperature difference. When a drop in power useage occurs, the MAF sends a signal to the Powertrain Control Module indicating the drop. The signal increases with the airflow into the engine.