What are the reasons for the cold start, flameout or jitter of the car?

Slight jitter is normal. If the jitter is serious, it needs to be checked.

The most common cause of automobile jitter is that the throttle valve is too dirty or the fuel injector has too much carbon deposit.

When there is too much carbon deposit in the engine, the gasoline sprayed by the fuel injection head will be absorbed by the carbon deposit during the cold start, which leads to the lean mixture during the cold start and makes it difficult to start. In this case, only when the gasoline adsorbed by carbon deposits is saturated, it is easy to run into the car. After running into the car, the gasoline adsorbed on carbon deposits will be sucked into the cylinder by the vacuum suction of the engine for combustion, which will thicken the mixture and dilute the combustible mixture of the engine, resulting in idling jitter after cold start.