What happened when the cold car started screaming for a second or two?

Carbon deposition, weak ignition, low cylinder pressure, unqualified fuel, etc.

More detailed reasons are as follows:

1 There is too much carbon deposit in the throttle, injector and air intake, which may be one or all of them.

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 cold start, which will lead to too thin mixture during cold start and make the start shake.

3 Mechanical failures such as ignition coil, spark plug and fuel injector. , resulting in cylinder missing.

4 oil pressure or cylinder pressure is low, resulting in insufficient power.

5 The fuel quality is unqualified.

6 Idle speed control valve is damaged or dirty.

7 Air leakage in the intake manifold.

8 engine arm or claw pad is damaged, etc.

10 engine oil is oxidized or low in grade, mainly due to poor low-temperature fluidity and inadequate engine cold start protection.

Two: It is recommended to go to a 4S shop or a repair shop and go in for inspection and maintenance to improve the safety performance of the car.