What Causes a Sudden Increase in Car Idle Speed?

[ErinDella]

Reasons for a sudden increase in car idle speed: 1. It may be caused by excessive air intake during idling, excessive fuel injection, or incorrect engine control signals; 2. During cold starts, the idle speed increases. Some all-aluminum engines dissipate heat too quickly and have good sealing, resulting in higher combustion efficiency upon restart. If the speed is too low during ignition, incomplete combustion may occur, leading to excessive carbon buildup or cylinder misfire. Therefore, the higher speed during ignition serves as protection for the engine; 3. Idle speed increases when the air conditioning is turned on. After turning on the air conditioning, the engine requires additional power to drive the compressor, increasing the load. Thus, more fuel is injected to compensate for this additional power, causing the idle speed to rise accordingly.