XT-6 2WD L6-2.7L SOHC (1989)
Idle Control Valve: Description and Operation
Bypass Air Control Valve
PURPOSE
The bypass air control valve modifies idle speed to bring it as close as possible to preset limits.
LOCATION
The control valve at the R.R. side of the intake manifold.
OPERATION
The By-pass air control valve is a DC motor driven valve. The ECU will send polarized voltage to the motor windings to either open or close the
valve. The valve closes off an air passage when the idle speed is above preset limitis, thus lowering idle speed. The valve opens the passage when
the idle speed is too low.
The opening and closing of the valve allows air to by-pass the throttle plate, modifying idle speed.
To improve driveability, the ECU prevents a sudden drop in engine rpm when the throttle is closed, similar to the dashpot function on a carbureted
vehicle.