
Unstable idle when using gas but normal when using fuel. Extended knowledge about car idling is as follows: 1. Causes: Poor spark plug performance; Vacuum tube leakage; High-voltage wire leakage; PCV valve blockage; Throttle position sensor failure; Idle stepper motor malfunction; Idle control valve failure; Abnormal throttle opening; Intake system leakage. 2. Hazards: Unstable car idling is mainly manifested as fluctuations in the tachometer needle during idling, unstable pointing, up and down movements. Unstable idling is often accompanied by idling vibrations. Unstable idling can be considered one of the most common engine faults, with the severity varying; Unstable idling refers to idle speed exceeding the expected value by ±20r/min or experiencing severe speed fluctuations; Engine idle performance has a significant impact on emissions, fuel consumption, and comfort, making it an important indicator for evaluating engine performance; During idling, the engine is separated from the transmission system with the throttle pedal fully released, the engine only overcomes its own resistance to operate without external power output.


