Inland idling, shaking, refueling, not shaking.

Reason: 1. Serious carbon deposit inside the engine: throttle carbon deposit, nozzle carbon deposit, spark plug carbon deposit and piston carbon deposit. When these carbon deposits accumulate to a certain extent, they will absorb the heat of combustion and even lead to deflagration and detonation.

2. Ignition system Q _: Due to excessive carbon deposition in the spark plug and insufficient ignition voltage, flashover will be affected, and single-cylinder or multi-cylinder fire will occur, and the engine will tremble and vibrate due to insufficient power.

3. Unstable fuel pressure: The fuel system includes fuel tank, gasoline filter, gasoline pump, oil-gas separator, tubing and fuel gauge. If one of them has problems, it will affect the instability of oil pressure.

4. Aging of engine internal parts: This will only happen after the vehicle has been used for a certain number of years or after driving. If the engine power is seriously reduced, it will cause trembling and vibration. Under normal circumstances, such cars are prone to tremble and vibration at low speed, and the symptoms have been improved to some extent after fuel supply.