7.1 Air Flow Measurement

Fig. 7-2 is an exploded view of the air flow sensor, the throttle valve, and their connecting air duct. As intake air is drawn past the air flow sensor flap, the flap opens and in turn actuates the potentiometer. The varying resistance of the potentiometer provides a signal to the control unit that is proportional to air flow. The air flow sensor also contains an intake air temperature sensor which measures the temperature of the incoming air.

The throttle valve is operated by the accelerator pedal via the accelerator cable, and controls the amount of air drawn in by the engine. The throttle valve is adjusted during manufacture and does not require any routine adjustment. The throttle valve can be adjusted if the factory settings have been tampered with.

Fig. 7-2.

Exploded view of throttle valve and air flow sensor. Inset shows air flow sensor terminals used for electrical testing.