Is Slight Idle Shaking Normal?

[LeBlakely]

Slight idle shaking is normal. Idle shaking occurs because the engine is running, and the oil does not follow up in time, causing the engine to lack optimal mechanical operating conditions or due to poor fuel injector atomization and improper idle adjustment, leading to engine shaking. If noticeable body shaking is observed when starting the vehicle or when the vehicle is parked with the engine still running, it is usually due to severe engine carbon buildup or a dirty throttle. When there is excessive carbon buildup inside the engine, the gasoline sprayed by the cold-start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts, making it difficult to start. In this situation, the vehicle will only start easily once the carbon deposits have absorbed enough gasoline to reach saturation. After starting, the gasoline adsorbed on the carbon deposits is then drawn into the combustion chamber by the engine's vacuum suction, enriching the air-fuel mixture again. This fluctuation between lean and rich air-fuel mixtures causes idle shaking after a cold start.