Changan Star D20 1 valve speed jitter is weak.

Need to check, the throttle is too dirty or the injector has too much carbon deposit.

The most common cause of vehicle vibration caused by too much carbon deposit in the engine is that the throttle valve is too dirty or the fuel nozzle has too much carbon deposit. When there is too much carbon deposit in the engine, the gasoline sprayed by the fuel nozzle will be absorbed by the carbon deposit when the cold car starts, which leads to the lean mixture when the cold car starts, making it difficult to start.