How often does the car clean the throttle nozzle?

The throttle shall be cleaned every 20,000-40,000 km, and the choke shall be cleaned every 40,000-60,000 km. Throttle is a controllable valve to control air entering the engine, which can be described as the "throat" of the engine. After the gas enters the intake pipe, it will be mixed with gasoline to form a combustible mixture, and the combustion is successful. The depth of the owner's stepping on the accelerator determines the size and suitability of the engine power. When the fuel nozzle is dirty, the car will have the following phenomena: 1, and the noise of the low-gear engine will become louder; 2. The throttle is unresponsive or the driving is not smooth. There is hysteresis after stepping on the accelerator. After stepping on the accelerator in neutral, the engine speed rises slowly.