Why can't the car catch fire after washing the nozzle and throttle, and it needs to be hit by stepping on the throttle?

Because of the carbon deposit, there will still be a certain gap after the throttle is closed, but it is blocked by carbon deposit. After cleaning, the carbon deposit is removed, but the throttle will temporarily stay in the original position, so the engine will have unstable idle speed or high idle speed. After cleaning the throttle and nozzle, the throttle must be initialized with a diagnostic computer; There is also a slight vibration of the engine, which will shake with the pedal through the throttle line.