What should I do if the visual x3 idling speed is too high?

Usually, the main reason for high idle speed is excessive intake air or incorrect engine control signal. Causes of high idle speed include air temperature sensor failure, water temperature sensor failure, throttle position sensor failure, air flow meter or intake manifold absolute pressure sensor failure, switch signal failure, idle speed control valve failure, engine control unit failure or matching setting problem.

1. Idle switch is not turned off.

When the idle contact is disconnected, the ECU determines that the engine is in a partial load state. At this time, the ECU determines the fuel injection quantity and time according to the air flow sensor, crankshaft position and speed signal. At this time, the engine is idling, and the intake air is less, which leads to the mixture being too rich and the speed increasing.

When the ECU receives the signal that the mixture is too rich from the oxygen sensor, it will reduce the fuel injection and increase the opening of the idle control valve, which will lead to the mixture being too lean and slow down the vehicle speed. When the ECU receives the signal that the mixture fed back by the oxygen sensor is too lean, it will increase the fuel injection and reduce the opening of the idle control valve to make the mixture too rich, thus increasing the speed.

This repetition makes the idle speed of the engine unstable. When idling, turning on the air conditioner, steering wheel and turning on the light will increase the load of the engine. In order to prevent the engine from stalling due to increased load, ECU will increase the fuel supply to maintain the balanced operation of the engine. When the idle contact is disconnected, ECU thinks that the engine is not in idle state and will not increase the fuel supply, so the speed will not increase.

Solution: Adjust or replace the throttle position sensor.

2. Idle speed control valve is faulty.

The normal idle speed of EFI engine is guaranteed by idle speed control valve (ISC). According to the signals of engine speed, temperature, throttle switch and air conditioner switch, ECU can increase the intake bypass passage of idle speed control valve or directly increase the throttle opening, thus increasing the intake air volume and improving the engine idle speed.

When the idle speed is higher than the set speed, ECU instructs the idle speed control valve to close the air intake bypass channel to reduce the air intake and the engine speed. Oil pollution and carbon deposition lead to the action card of idle speed control valve being issued or the throttle valve not being closed correctly, which will make ECU unable to adjust the engine idle speed correctly and lead to unstable idle speed.

Troubleshooting: Clean or replace the idle speed control valve, and basically set the idle speed with a special decoder.