Idle Speed/Throttle Actuator - Electronic: Description and Operation

Idle Valve:

The idle control valve maintains proper idle speed under the various engine load conditions. The idle control valve consists of two opposed windings, an armature and a rotary slide. The DME control unit regulates idle speed by controlling the amount of time each winding is energized. The amount of bypass air is determined by a variable orifice in the idle control valve. The DME control unit compares the actual engine speed with the programmed speed. By varying the time each winding is energized, the opposing forces on the armature cause it to take a fixed position, allowing enough bypass air to maintain the correct idle speed.