What are the causes of idle vibration in new cars?

[DelGabriel]

New car idle vibration can be caused by poor fuel combustion, insufficient ignition energy due to spark plug failure, air leakage in the intake system or low fuel pressure, poor fuel injector atomization, improper idle adjustment, malfunctioning idle control valve or bypass air valve, carbon buildup on valves and intake ports, etc. Here is the relevant content introduction: Intake manifold or various valve leaks. When unwanted air, gasoline vapor, or combustion exhaust enters the intake manifold, it can cause the air-fuel mixture to become too rich or too lean, leading to abnormal engine combustion. When the leakage affects only individual cylinders, the engine will experience more severe vibration, which has a greater impact on new car idle conditions.