Iacv (Idle Air Control Valve) - Honda MUV700 big red Service Manual

TECHNICAL FEATURES
IACV (Idle Air Control Valve)
The lACV consists of a step motor and a slide valve, and controls the amount of air bypassed around the closed thronle
valve. With the ignition switch ON, the amount of idle air is determined by the PCM from information detected by various
sensors, During engine start-up or while maintaining idle (throttle valve closed), the amount of inlet air is continuously
adjusted according to various sensors' information .
This system eliminates the need for a manual idle speed adjustment and high altitude adjustment settings.
THROTILE BODY
STEP MOTOR
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SUDE VALVE
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OPERATION
The PCM controls the IACV during engine idling only, so the PCM stops controlling the IACV and leaves it in the closed
position when the PCM detects the following:
• Throttle valve open
• Gear position switch is in gear position (except neutral)
During engine idling and warm up, from the time the ignition switch is turned ON, the PCM controls the IACV step motor
as follows:
With the ignition switch ON
• When the ignition switch is turned ON, the IACV is initialized and
the step motor will operate: The slide valve goes from the open
position, to the closed, and again to the open position.
Engine starting and warm up
• While the throttle valve is closed, the bypass opening is optimized
by the IACV, and the correct amount of inlet air passes through
allowing proper engine starting.
• After the engine has started, the PCM controls the IACV step motor
to adjust the slide valve pOSition by processing various sensors'
information. This results in a reduced amount of bypassed air com-
pared to the amount during engine start-up, and initiates engine
warm-up for sever a! minutes.
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STEP MOTOR
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I~SUDE
VALVE
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