Air Flow Meter/Sensor: Description and Operation

Air Flow Meter:

The Airflow Meter, located in the right front corner of the engine compartment, is a sliding core type that moves easily, causing minimal resistance to intake air. A spring loaded measuring core, connected to a potentiometer, moves in relation to the volume of incoming air. As measuring core and potentiometer move in and out, ECU reference voltage signal varies and is calculated as differing quantities of intake air.

Incorporated into the airflow meter is an intake air thermosensor. Because sensor resistance fluctuates with temperature, the ECU can calculate changes in reference voltage as temperature variations. This input is used by the ECU to regulate fuel quantity in relation to air density.

With intake air quantity and temperature (density) information, the ECU is able to make precise fuel injection calculations that account for the spectrum of conditions between cold and warm air. Cold air is denser (more molecules per unit of volume, such as a combustion chamber) than warm air, requiring differing amounts of fuel for optimum performance and low emissions.