How to judge that the throttle valve needs cleaning?

The trick is: start the car, put it in neutral, boom the throttle to about 3000 rpm, and release the throttle. Pay attention to the pointer of the tachometer. When you release the throttle, the pointer will quickly drop to a low speed. If the accelerator is not dirty, when it drops to about 1000~ 1200 rpm, the pointer will stop, just like a car suddenly stepping on the brakes while driving, and then continue to drop to about 800 rpm. If there is no such pause process at 1000 rpm to1200 rpm, congratulations, you have to spend money to wash the throttle quickly.

After asking a lot, I finally know the principle. It turns out that when the engine is designed with no load, the fuel injection will automatically stop when the throttle falls behind the fuel filler door. When the speed drops to 1000~ 1200 rpm, fuel injection will resume, and then it will be gradually reduced to idle fuel injection. Form a buffer and don't turn off the fire.

If you find it useful, post it back. . . .