Air Flow Meter/Sensor: Description and Operation

Air Flow Sensor:

PURPOSE
Measures volume and temperature of intake air. With intake air quantity and temperature (density) information, the PCME makes 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) than warm air, requiring differing amounts of fuel for optimum performance and low emissions.

LOCATION
Right front corner of engine compartment near air cleaner.

OPERATION
A spring-loaded measuring core, connected to a potentiometer, moves in relation to incoming air volume. As measuring core moves in and out, PCME reference voltage signal from the potentiometer varies and is calculated as differing quantities of intake air.

Incorporated into the sensor is an intake air thermosensor. Because sensor resistance fluctuates with temperature, the PCME calculates changes in reference voltage as temperature variations. This input is used to regulate fuel quantity in relation to air density.

CONSTRUCTION
Sliding core type sensor with potentiometer and built-in intake air thermosensor.