Idle Speed/Throttle Actuator - Electronic: Description and Operation

The idle control valve keeps the idle speed stable under various engine operating conditions. The idle control valve is located in-line with the bypass hose which is connected to the throttle valve plate. The valve consists of two opposed windings, an armature and a rotary slide. The CIS-E control unit regulates the idle 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 CIS-E 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. With the ignition switched off, the idle control valve is held open by spring action. When the ignition is switched to the run (ON) position and the engine is off the valve is activated by a specific voltage from the CIS-E control unit, depending upon coolant temperature. After the engine is running the nominal speed is maintained between 720 RPM and 900 RPM depending upon inputs to the idle speed control unit.