Idle Speed Adjuster

The idle speed adjuster is an electrically controlled solenoid that opens and closes an orifice. With the ignition off, the orifice is completely open. With the ignition on and engine not running, the orifice is open and the adjuster is operated by 0-1.5 volts from the control unit,

When the engine is running, the orifice is decreased in size as the adjuster receives 4-5 volts. At 5 volts, the orifice is closed. When engine speed is over 900 RPM, the orifice is kept slightly open by 4.5 volts so that the engine will not stall if the throttle is closed suddenly.