The throttle opening is 15% at idle speed.

Are you asking whether the throttle opening of 15% is abnormal at idle speed? This is abnormal and needs to be cleaned or replaced.

According to car home Forum, when idling, the throttle opening of 15% is abnormal, and the normal opening should be 3%. If it exceeds 3%, the throttle valve needs to be cleaned or replaced.

Throttle is a controllable valve that controls air to enter the engine. After the air enters the intake pipe, it will be mixed with gasoline to form a combustible mixture, and the combustion is successful. It connects the air filter and the engine block, and is called the throat of the automobile engine.