Idle Speed/Throttle Actuator - Electronic: Description and Operation

Fig. 88 Idle Control System Wiring And Vacuum Hose Diagram:

The idle speed and air mixture of the engine is controlled by the Electronic Air Control Valve (EACV) and the fast idle valve. The valve changes the amount of air bypassing into the intake manifold in response to electric current sent from the ECU. When the EACV is activated, the valve opens to maintain the proper idle speed.

1. After the engine starts, the EACV opens for a certain time. The amount of air is increased to raise the idle speed about 150-250 rpm.

2. When the coolant temperature is low, the EACV is opened to obtain the proper fast idle speed. The amount of bypassed air is thus controlled in relation to the coolant temperature. When the coolant temperature is below 50°C (122°F), it also activates the fast idle valve to prevent the idle speed from dropping.