I went to the garage to clean the throttle. As a student, I opened the hose and sprayed it directly on the engine. Master immediately stopped spraying hoses. Is it harmful?

No problem. The distance between the throttle and the air inlet of the engine is very short, so a small amount of throttle cleaner may enter the engine when cleaning the throttle, and the effect is negligible. After a few throttling, there is nothing. Moreover, the accelerator cleaner will not have a great adverse effect on the engine, not to mention only a little, and the problem of black smoke may be short-lived. There won't be any problems