Air Flow Meter/Sensor: Description and Operation

Air Flow Meter:

PURPOSE
Measures quantity of intake air and signals PCME. Unit also contains an intake air temperature sensor.

LOCATION
Attached to air cleaner assembly, left side engine compartment.

OPERATION
The airflow sensor is a sliding cone type with a measuring cone in a large venturi, supported by a light spring. Incoming air moves the cone in proportion to the volume of air (more air, more movement). As the cone moves, a sliding potentiometer attached to the cone also moves. The PCME reads the change in resistance through the potentiometer and calculates the volume of air entering the engine.

Incorporated into the sensor is an intake air temperature sensor. The sensor is a negative temperature coefficient thermistor; as temperature increases, resistance decreases. Cold air is more dense than warm air. The PCME measures sensor resistance and calculates incoming air temperature. The PCME adjusts fuel injection quantity and idle speed control to compensate for changes in air density due to changes in temperature.