After I changed the oil, I cleaned the throttle. When the cold car started, it would emit blue smoke for about 2 minutes.

The fact that the cold engine is not easy to start is related to the dirty throttle, because the throttle is closed slowly when it is dirty, and the air intake is large, so the cold engine is not easy to ignite. And if you clean the throttle, the air intake will be less, and the engine will be easy to start, because the gasoline has not completely burned at this time. However, the tail gas should be white smoke, and your tail gas should be blue smoke from burning engine oil. Open it for a while, and then look at the oil gauge. It may be that there is a little too much oil, or it may be caused by the throttle cleaner flowing into the cylinder and burning. Look at it later. If not, you have to change the piston ring.