Idle Up Control Valve: Description and Operation

A small electrically operated valve is used to control the idle speed. The valve consists of a small single winding electric motor. A rotary valve and a return spring are attached to the motor's armature. This is a different design from previous versions.
The motor is operated by a cycled DC voltage (duty cycle) which will cause the armature to work against the return spring. The strength of the motor's current (duty cycle) will determine the position of the armature and the size of the rotary valve opening.
If the valve should fail for any reason, the return spring will force the armature against a stop. This will establish a fixed rotary valve opening and cause a warm idle speed of about 900 RPM for emergency operation.





The idle stabilization valve is operated by the fuel injection control unit. The system will control the engine idle speed at the following levels:

COLD ENGINE
Approximately 1,000 RPM, this speed will vary depending on the engine temperature. Idle speed will decrease from this value until it reaches the warm engine value.

WARM ENGINE 720 +/- 70 RPM

A/C Switched 720 +/- 70 RPM
ON

With this system, no idle speed adjustments are possible or necessary. Because of this, there is no test lead to measure the idle stabilization valve's duty cycle.
To insure proper system operation, make sure the idle air bypass screw is turned in fully on its seat in the throttle housing.