Air Flow Meter/Sensor: Description and Operation

Volume Airflow Sensor:

PURPOSE
Measures airflow into the engine intake system with a potentiometer rotated by a spring loaded measuring plate.

LOCATION
Attached to air cleaner assembly on left side of engine compartment.

OPERATION
Incoming air moves the measuring plate in relation to volume (more air, more movement), overriding spring tension. As the measuring plate moves, contacts in the attached potentiometer also move, varying potentiometer resistance and the input voltage signal sent to the PCME.

Incorporated into the airflow meter is a fuel pump switch and an intake air temperature sensor. The fuel pump switch prevents fuel pump operation when the engine is not running and the ignition switch is "ON." The sensor measures ambient air temperature to allow PCME fuel compensation based on air density.

The PCME factors intake air temperature into its fuel quantity calculations because density varies with temperature (cold air is denser than warm). With both flow volume (measuring plate and potentiometer) and temperature information, the PCME can make precise mixture adjustments under a wide range of operating conditions.