Idle Air Control

- The ECM activates the idle air control solenoid valve in advance to control the amount of by-pass air flowing through the throttle valve in relation to signals emitted from the crankshaft position sensor, camshaft position sensor, engine coolant temperature sensor and A/C switch, so that the proper idle speed specified for each engine load is achieved.
- The idle air control solenoid valve is a rotary type and operates by duty cycle. For this reason, the by-pass air flow is regulated by controlling the duty ratio. The relationship between the duty ratio and by-pass air flow is as follows:
- Duty ratio (high) -> Increases by-pass air flow.

- By-pass air control features the following advantages:
- Compensation for engine speed under A/C (air conditioning) system and electrical loads.
- Increase in idle speed during early stage of warm up period.
- A dashpot function during the time the throttle valve is quickly closed.
- Prevention of engine speed variations over time.