Scirocco L4-1781cc 1.8L DOHC (1986)
Idle Speed/Throttle Actuator - Electronic: Description and Operation
Fig. 14 Idle Speed Control Valve
The idle speed control valve, Fig. 14, supplies the engine with the proper amount of air, through a bypass around the throttle plate, to maintain the
correct idle speed. It takes over the function of the auxiliary air valve which is no longer needed. The idle actuator is controlled by the ECU.
Information data processed within the ECU to determine the signal to send to the idle speed controller include, engine speed, coolant temp, idle speed
signals, drive gear position, and whether the a/c compressor is activated.
With the ignition switched off, the idle control valve maintains a set position (limp home mode). With the ignition switched on (and the engine off),
the idle valve is activated by a predetermined voltage signal. Once the engine is started, the ECU will vary the voltage to maintain a constant idle speed.
