The vane type air flow meter is a commonly used air volume measurement device on Toyota EFI engines. The meter consists of a measuring plate, which is spring loaded closed by a return spring, and a potentiometer attached to the plate, which varies an electrical signal to the ECU as the position of the plate changes. Air volume entering the engine is directly proportional to the amount of movement detected from the measuring plate. Additionally, the air flow meter incorporates a fuel pump enable contact which breaks the ground circuit of the circuit opening relay if the engine stops running.
The air flow meter is placed in series between the air cleaner and the throttle body, thereby measuring all air which enters the engine. Integrated with the air flow meter is an intake air temperature sensor and an idle mixture by-pass passage.
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