Function of Idle Speed Adjusting Knob for Isuzu Freight Cars

This function is used to adjust the idle speed when the engine is shaking, because the idle speed is low when the vehicle is cold or with air conditioning.

When the idle load of the engine increases, ECU controls the idle control valve to increase the air intake, thus improving the idle speed and preventing the engine from being unstable or flameout; When the engine idle load decreases, ECU controls the idle control valve to reduce the intake air, thus reducing the idle speed and avoiding excessive idle speed.

The idle speed control valve is installed on the vent hole beside the throttle. According to the ignition signal, when the engine speed is lower than 750 rpm, the idle control valve will be activated in time to increase the engine speed, and when the engine speed exceeds 1050 rpm, the idle control valve will stop working.

In vehicles equipped with air conditioning system, this control valve is also called idle acceleration valve. After the air-conditioning compressor operates, the engine load is generated, which reduces the engine idle speed, and the idle speed control valve acts accordingly to maintain the idle speed stability. When the working parameters of the engine deviate from the normal value, the idle speed is adjusted by using the idle speed control valve.

Idle speed is regulated by controlling the amount of air bypassing the throttle body. After the engine is started, the idle speed control valve is opened for a period of time, and the intake air is increased, so that the engine idle speed is increased by about 150r/min-300r/min.

When the engine coolant temperature is low, the idle speed control valve is opened to obtain a suitable fast idle speed. The engine computer controls the position of the plunger of the idle control valve by changing the signal intensity sent to the idle control valve according to different coolant temperatures.