The engine has no idle speed. Generally, the throttle is turned off when it is placed at the idle position. When the throttle is slightly enlarged, the speed is increased quickly and cannot be stably operated at a low speed. Reason a. The governor idle spring is too soft or broken. b. The governor sensing element is worn too much. c. The plunger of the fuel injection pump is seriously worn. d. The temperature is too low. e. The cylinder pressure is too low. Diagnosis and treatment a. There is no idle speed at cold start, which is generally a normal phenomenon. This is because the temperature is too low, the viscosity of the oil is too large, the internal resistance of the engine is increased, the spray and evaporation conditions of diesel oil become worse, resulting in the engine can not maintain the minimum stable speed operation, when the throttle is raised, it will turn off quickly. In this case, the throttle can be adjusted to run at a slightly higher idle speed, and then resume i