Idle Speed Control System

Idle Speed Control System:

PURPOSE

The Idle Air Control System allows for precise control of the engine idle during cold, warm and high load conditions.

Idle Air Adjusting (IAA) Unit:

LOCATION

Idle Control Housing and Air Regulator are on the intake manifold.

OPERATION

Idle speed is controlled by fine adjustment of the amount of air allowed to bypass the throttle valve.

Two different devices, all part of the Idle Control System, are used to control engine idle. The devices are:

1. Idle Air Control Valve-Air Regulator (IACV-Air Reg)
^ Used to provide additional by-pass air during cold engine operation. Allows cold fast idle. Is activated by 12 VDC.
2. Idle Air Control Valve-Auxiliary Air Control (IACV-ACC) Valve.
^ Used to provide fine control of the engine idle during normal conditions. Is activated by a duty cycle signal from the ECM at a rate of 100 - 200 Hz.