940 L4-2.3L SOHC VIN 88 B230F (1992)
Idle Control Valve: Description and Operation
Bendix
Idle Air Valve
Sent by the fuel injection ECU:
PURPOSE AND LOCATION
The idle air valve (located below the intake manifold) provides the control for constant idle speed. In order to set the correct air valve opening to
achieve constant idle speed, the fuel injection control unit uses information from the throttle valve switch and the ignition control unit (RPM
signal) to regulate the output current to the idle air valve.
The idle speed should remain constant and compensate for changing engine load conditions (A/C operation, headlights, windshield wipers...).
Idle Air Valve Construction
CONSTRUCTION
The idle air valve consists of a solenoid, plunger, air valve and electrical connector to the ECU.
OPERATION
When the throttle valve switch idle contacts are closed during idling, the fuel injection control unit will send a current to the idle air valve solenoid
to keep the idle speed at the correct level. The solenoid controls the plunger which is connected with the air valve.
As the solenoid gets energized, the plunger opens the air valve, thus letting air by-pass the throttle valve. A constant idle speed is maintained by
the variable opening of the air valve. This speed is not preset in the fuel injection ECU, it bases the control current on memorized experience.
The idle air valve operates at all engine speeds, thus preventing a unnecessarily high vacuum in the intake manifold should the throttle valve
suddenly close.
The idle air valve will close when there is no voltage signal (ignition OFF, bad electrical connection...).
