What's the matter that the outboard oil valve can't return automatically?

There is too much carbon and dirt in the throttle and the surrounding air intake, and the cross-sectional area of the air passage changes, which makes the control unit unable to accurately control the idle intake, resulting in the mixture being too rich or too thin, which makes the combustion abnormal.

Spark plugs will also deposit carbon, which can be cleaned to restore the activity of spark plugs, but some spark plugs will have poor performance when their service life is approaching.