What causes intermittent idling vibration in the Audi A4L?

[OAnna]

The following are the reasons for intermittent idling vibration in the Audi A4L: 1. Dirty throttle valve and fuel injectors: When there is excessive carbon buildup, the gasoline sprayed by the fuel injectors does not enter the cylinders normally; instead, most of it is absorbed by the carbon deposits. This results in an overly lean air-fuel mixture, ultimately causing difficulty in starting the car. After the engine starts, the gasoline attached to the carbon deposits is absorbed and burned again, causing the engine's air-fuel mixture to become too rich. The unstable state of the air-fuel mixture leads to idling vibration. 2. Ignition system failure: The main areas to check are the spark plugs, high-voltage wires, and ignition coils. Special emphasis should be placed on the spark plugs. If the spark plugs have excessive carbon buildup, it is recommended to replace them directly. 3. Unstable fuel pressure: For this issue, it is advisable to visit a 4S shop for inspection and repair, as professional diagnostic equipment is required for analysis. The items to be checked include fuel supply pressure, intake pressure sensor, etc.