The engine speed fluctuates slightly.

It is caused by abnormal throttle, abnormal battery, engine carbon deposit, actuator failure of intake system, ignition system failure, air leakage of intake manifold, fuel system failure, etc.

For abnormal throttle, it is necessary to replace the throttle to solve it. For the abnormal battery, replacing the battery is helpful to solve the problem. For engine carbon deposit, cleaning engine carbon deposit is helpful to improve unstable speed. For the actuator failure of intake system, ignition system failure, air leakage of intake manifold, fuel system failure, etc., it is necessary to carry out corresponding inspection and maintenance, such as replacing ignition coil, spark plug and other parts, cleaning fuel nozzle or replacing filter.