Air Flow Sensor Plate Position Sensor: Description and Operation

Air Flow Sensor Plate Potentiometer:

The air-flow sensor plate potentiometer which is located on the air flow sensor housing informs the CIS-E control unit of the need for extra fuel enrichment during cold-engine part-throttle acceleration. The potentiometer consists of a wiper brush working on a carbon film. Based on sensor plate position the potentiometer signals how fast and how far the sensor plate moves as air flow increases. This information helps to prevent the familiar "flat spot" that accompanies an abrupt opening of the throttle valve during cold engine operation.

Potentiometer Voltage Graph:

The E.C.U. provides the air-flow sensor plate potentiometer with a 5 volt reference signal. During acceleration, the movement of the sensor plate produces a modified voltage signal back to the E.C.U. via the potentiometer wiper. From this input, the E.C.U. calculates the need for enrichment and sends a compensating voltage to the differential pressure regulator. For approx. 1 second, the additional current to the differential pressure regulator allows more fuel to be injected into the cylinders. The greatest enrichment takes place when the engine is cold; partial enrichment when the engine is cool and no enrichment when the engine is at normal operating temperature.