D21 Hardbody 2WD V6-2960cc 3.0L SOHC MFI (VG30E) (1991)
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Auxiliary Air Control (AAC) Valve: Description and Operation
Idle Speed Control System
CIRCUIT OPERATION
The idle speed is controlled by the amount of air that is allowed to bypass the throttle plate through the auxiliary air control (AAC) valve. The
AAC valve is turned ON and OFF at a rate between 100 and 200 Hz. The ECU calculates the duty cycle (frequency of ON/OFF signals) necessary
to maintain the proper idle speed, compensating for transmission gear position, electrical and accessory loads.
IACV-Auxiliary Air Control Valve
AUXILIARY AIR CONTROL VALVE
The auxiliary air control (AAC) valve controls the idle speed. It receives a pulse signal from the ECU which opens and closes an air passage
allowing a precise amount of air to bypass the throttle plate.
