Accord EX Coupe V6-3.0L (2001)
Idle Air Control Valve: Description and Operation
Idle Control System
When the engine is cold, the A/C compressor is On, the transmission is in gear, the brake pedal is pressed, the P/S load is high, or the alternator is
charging, the PCM controls current to the IAC valve to maintain the correct idle speed. Refer to the System Diagram to see the functional layout of the
system.
Idle Control System Diagram
The idle speed of the engine is controlled by the IAC (Idle Air Control) valve:
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After the engine starts, the IAC valve opens for a certain amount of time. The amount of air is increased to raise the idle speed by about 150 - 300
rpm.
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When the engine coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of bypassed air is thus
controlled in relation to engine coolant temperature.
Idle Air Control (IAC) Valve
To maintain the proper idle speed, the IAC valve changes the amount of air bypassing the throttle body in response to an electrical signal from the PCM.