What Causes an Engine to Idle at an Abnormally High Speed?

[MacElliana]

The reasons for an engine idling at an abnormally high speed are as follows: Fuel Injection System: If the fuel supply system pressure is insufficient or the fuel injectors are clogged, leading to poor atomization of the fuel injectors, it can cause idle speed issues. Check if the fuel filter is clogged or dirty, and replace it if any abnormalities are found. Also, inspect whether the fuel pressure regulator is functioning properly, and then check the fuel pressure. The normal fuel pressure value should be between 250 kPa and 300 kPa. Idle Speed Control System: If the idle speed control valve is dirty, stuck, or its control circuit is open, when the engine needs to increase the idle speed, the command issued by the computer cannot be executed, and the intake air volume cannot meet the load requirements, leading to idle speed issues or engine stalling.