What are the reasons for unstable idle speed and easy stalling of a car?

[KeiraDella]

Here are the common causes of idle stalling: 1. Oil contamination impact: The normal idle speed of an electronically controlled fuel injection engine is determined by the idle speed control valve. The electronic control unit (ECU) calculates signals such as engine speed and temperature to adjust the opening of the idle speed control valve, increasing the intake air volume to raise the engine idle speed. If oil contamination or carbon deposits cause the idle speed control valve to stick or the throttle valve to not close properly, the ECU cannot accurately regulate the engine idle speed. 2. Intake pipe leakage: Normally, the intake air volume must be strictly controlled. If there is a leak in the intake pipe, the air flow sensor cannot measure the actual intake air volume, leading to inaccurate control by the ECU and resulting in unstable idle speed. 3. Fuel injector leakage or blockage: If the fuel injector leaks or is blocked, or if there is a circuit fault affecting the quantity and quality of fuel injection, it cannot inject fuel as instructed by the ECU. This causes the air-fuel mixture to be too rich or too lean, leading to poor performance in individual cylinders and unstable idle speed.