Vane Type Air Flow Meters Vs General Information

The vane type air flow meter is located in the air induction system inlet pipe between the air cleaner and the throttle body. It is composed of the measuring plate, compensation plate, return spring, potentiometer, and by-pass passage. The sensor also incorporates the idle mixture adjusting screw (factory sealed), the fuel pump switch, and the intake air temperature sensor (which will be addressed later in this lesson). Because intake air volume is a direct measure of the load placed on an engine, the vane type air flow meter provides the most important input to the ECU for fuel and spark calculations.

,n ™te To Air Intake Chamber

Via Throttle Valve

Idle Mixture Adjusting Screw

By-pass Passage Measuring Plate

,n ™te To Air Intake Chamber

Via Throttle Valve

Idle Mixture Adjusting Screw

By-pass Passage Measuring Plate

When air passes through the air flow meter, it forces the measuring plate open to a point where it balances with the force of the return spring. The damping chamber and compensation plate prevent vibration of the measuring plate during periods of sudden intake air volume changes.

The potentiometer, which is connected to the measuring plate and rotates on the same axis, converts the mechanical movement of the measuring plate into a variable voltage signal. Movement of the measuring plate and the analog voltage signal produced by this sensor are proportional to the volume of air entering the intake manifold.

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