Idle-RPM Control System

An electronically governed idle-rpm control valve keeps the idle speed stable under the various engine operating conditions. Measured intake air from the airflow meter bypasses the throttle plate through the idle-rpm control valve and subsequently calls for additional fuel injection. The amount of by-pass air is determined by a variable orifice in the valve.

The idle-rpm ECU controls the orifice via the rpm-signal generated from the starter ring teeth. The opening is enlarged or reduced by a solenoid according to operating conditions (e.g. engine friction, automatic in 'DRIVE' or air condition 'ON'). The system is calibrated to stabilize at 950 rpm below 45°C coolant temperature and 700 rpm above 45°C.

With automatic transmission in 'DRIVE' the system stabilizes at 700 rpm. It rises to 850 rpm if air conditioner is switched on and the outside temperature is below -5°C with automatic transmission in 'P' or 'N' position only.