Why does the car vibrate when idling but not when refueling?

The car vibrates when it is idling, but it does not vibrate when refueling. It may be that the engine oil adsorbed on the carbon deposit is sucked into the cylinder by the vacuum suction of the engine for combustion, resulting in a thicker mixture and the car will not shake. Vibrates at idle.

　　

The idle speed of the engine is called the idle speed of the engine, and the size of the idle speed can be adjusted by adjusting the size of the damper. Idle speed is a working condition of the car, which means that the engine is running in neutral. The idle speed of the engine with excellent working performance is generally 550~800 rpm. When the car's idling speed has problems, it will cause engine noise. When the engine is running, the accelerator pedal is released, and the engine will be in an idling state. Adjusting the idling speed should not be high or low, which will cause wear and tear on the engine and needs to be repaired in time.