Idle Speeds Control

Idling is maintained steady by controlling idle speed according to the operating condition of the engine and engine load when the accelerator pedal is not depressed.

ECM controls idle speeds according to the following sensors and signals.

• Engine coolant temperature sensor
• Pressure sensor downstream of throttle valve (Engine load)
• Battery voltage
• A/C auto amp. (air conditioner activation status)

ECM adjusts idle speed through the throttle valve control and determines fuel injection time according to the amount of intake air. In addition, ECM can adjust the ignition timing up to 20 degrees in retard or advance direction to stabilize idle speed.

• During warm-up
• Shifting to D or R range
• Turning on air conditioner compressor
• Purge

DURING WARM-UP

During warm-up, ECM controls idle speed according to coolant temperature to quickly increase the catalyst temperature to the operating temperature after engine start.

Prerequisites for warm-up stage

• Engine coolant temperature is 40°C (104°F) or less
• N or P range

ECM increases idle speed to approximately 1, 100 - 1, 300 RPM for approximately 20 seconds after engine start. After this, if coolant temperature is less than 70°C (158°F), ECM increases idle speed 50 - 100 RPM more than the standard idle speed additionally for approximately 50 seconds.

SHIFTING TO D OR R RANGE

ECM receives a shift position signal from TCM via drivetrain CAN communication, and when the shift position is in D or R range, ECM decreases idle speed to reduce creeping of the vehicle.

TURNING ON AIR CONDITIONER COMPRESSOR

To prevent engine speed from decreasing due to the activation of air conditioner compressor during idling, the A/C auto amplifier transmits an A/C status signal to ECM before turning ON the air conditioner compressor. ECM controls idle speed according to the signal.

PURGE

The idle speed control reduces speed fluctuation resulting from purge.