What are the causes of unstable idle speed in gasoline engines?
1 Answers
Excessive carbon deposits in the throttle valve and surrounding intake passages can change the cross-sectional area of the air passage, making it difficult for the control unit to precisely regulate the idle air intake. This may also lead to an overly rich or lean air-fuel mixture, causing unstable idle speed in the car. The engine's intake system has numerous components, such as the throttle motor, idle speed stepper motor, duty cycle solenoid valve, air flow meter, and intake pressure sensor. Faults or damage to these components can result in unstable idle speed. The specific causes of unstable idle speed in gasoline engines are as follows: 1. Excessive carbon deposits in the throttle valve and air flow meter: The throttle valve and air flow meter are prone to dirt accumulation. Most modern cars use electronic throttle valves, which can be affected by even minor carbon deposits. Excessive carbon deposits in the throttle valve can cause throttle response issues, severe power loss, and unstable idle speed. 2. Dirty air flow meter: This can lead to incorrect air flow signals. Since the intake air volume determines the fuel injection volume, this directly results in inaccurate fuel injection, increasing fuel consumption and causing severe power deficiency. Therefore, replacing the air filter is crucial, and it is recommended to clean it every 30,000 kilometers. 3. Excessive carbon deposits in the cylinder combustion chamber and pistons: Too much carbon buildup in the combustion chamber can absorb some of the gasoline, prolonging the ignition start time. 4. Excessive carbon deposits: These often form on the valves and piston rings, indirectly causing insufficient cylinder pressure. Cold starts are more likely to result in unstable idle speed, which improves when the engine warms up. There can be many reasons for unstable idle speed in daily driving, such as vacuum leaks or faulty spark plugs.
