What is the problem of unstable idle speed of freight cars?

The air flow meter detects the amount of air entering the engine, which is one of the main bases for ECU to control fuel injection. Due to the failure of the air flow meter and its circuit, the ECU cannot receive the air flow signal, or the received signal is distorted, the fuel injection quantity of the injector is inaccurate, the mixture is too rich or too thin, the speed is too low, or there is a fire, and the idling operation is not soft. The failure of idle air conditioner will affect the incorrect adjustment of idle air conditioner. The common reason is that the throttle motor is damaged or hairpin; Idle stepper motor, duty ratio solenoid valve and rotary solenoid valve are damaged or stuck. Reasons for unstable idle speed of freight cars: 1. Due to pollution, mechanical parts wear, installation errors and other reasons. , the power of each cylinder changes, resulting in unbalanced power of each cylinder and unstable idle speed of the engine; 2. Too much carbon and dirt are deposited in the throttle and the surrounding air intake, and the cross-sectional area of the air passage changes, so the control unit cannot accurately control the idle intake, and the mixture is too rich or too thin, resulting in abnormal combustion; 3, the fuel pressure is too low, the oil is covered by fog, the spray quality is poor, and only a part of oil droplets appear in the serious nozzle. The main performance is that the mixture is too thin, the engine idle speed is unstable, the speed is low, and it is often accompanied by fire.