Old Feng Fan's engine is shaking.

First, there are several main reasons for the start-up jitter of the cold car: carbon deposition, weak ignition, low cylinder pressure, unqualified fuel and so on. The more detailed reasons are as follows: 1. There are too many carbon deposits in throttle, fuel injector and air intake, which may be one or all of them. 2. When the engine has too much carbon deposit, the gasoline sprayed by the fuel injection head will be absorbed by the carbon deposit during cold start, leading to cold start.