What Causes Severe Idle Vibration in a New Car?

[JuliaLynn]

Here are the reasons for severe idle vibration in a new car: 1. Severe engine carbon buildup: When there is excessive carbon buildup inside the engine, it can cause idle vibration after a cold start. This happens because the excessive carbon deposits absorb the injected gasoline, resulting in an overly lean air-fuel mixture that makes starting difficult. The engine can only start once the mixture reaches a certain level, but then the excessive carbon buildup causes the mixture in the cylinders to become too rich, leading to engine vibration. 2. Ignition system issues: Problems with the ignition system can also cause idle vibration, typically due to excessive spark plug carbon buildup.