How to check whether the throttle valve needs cleaning?

Failure phenomena such as slow acceleration, unstable idle speed and power drop can all indicate that the throttle valve is too dirty and needs cleaning. The following is the method for judging that the throttle valve needs cleaning: 1. When idling, the tachometer is unstable, indicating that the throttle valve is too dirty and needs cleaning. 2. The EFI car is in neutral, slamming on the accelerator for 3000 revolutions and then suddenly collecting oil. Pay attention to the pointer of the tachometer. When the pointer quickly drops to 1, 000 turns to 1, 200 turns, the pointer will pause a little, then drop to about 800 turns, and the throttle is slightly dirty. When the pointer quickly drops below 800 rpm or even 700 rpm, and then slowly rises to about 800 rpm, and the idle speed is from small to large, then the throttle valve is seriously fouled and needs to be cleaned immediately.