Excelle 1.8 What should I do if the speed increases when the manual gear is in neutral?

For the question you asked, it may be because the carbon deposit blocked the idle passage, causing the throttle or idle motor to jam or exceed its adjustment range, or because too much carbon deposit caused the throttle shaft to jam and could not return, resulting in the idle speed rising after receiving oil. After cleaning the throttle, the idle speed of oil collection will increase, which has happened many times. This is because when cleaning the carbon deposit, the carbon deposit solution enters the throttle shaft, causing the throttle shaft and the valve body base to get stuck. It is also possible that the throttle valve cannot completely return to the initial position set by the manufacturer because it is not initialized after cleaning, and the throttle valve has a large opening, which leads to the phenomenon of high idle speed. It may be the engine computer again, but it needs a special diagnostic computer to determine. I hope my answer is helpful to you.