What Causes the Idle Vibration of Audi 2.0T When Cold?

[MaryDella]

Idle vibration during cold starts is fundamentally caused by poor combustion in the cylinders. Below is an analysis of the reasons for idle vibration during cold starts:1. Excessive engine carbon deposits: The most common cause of car vibration is a dirty throttle body or excessive carbon buildup in the fuel injectors. When there is too much carbon inside the engine, the fuel sprayed by the injectors during a cold start is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts, making it difficult to start. It is recommended to clean the carbon deposits.2. Ignition system issues: After prolonged use, the spark plugs' ignition gap and timing control may vary. However, the ECU cannot detect this deviation, leading to a discrepancy between actual and theoretical conditions. As a result, some cylinders produce less power, causing vibration. It is recommended to replace the spark plugs.3. Unstable fuel pressure: If body vibration is noticed during cold idle, check whether the fuel supply pressure and intake pressure sensors are functioning properly. If the fuel pump's supply pressure is abnormal or the intake pressure sensor's values are incorrect or malfunctioning, it can cause cold start vibration. The solution is to check the fuel pressure.