What is the cause of the abnormal noise in the Audi A3?

[AmeliaMarie]

The main cause of abnormal noise in the Audi A3 is the accumulation of carbon deposits in areas such as the throttle body, intake manifold, and valves. Reasons for shaking: When the engine is cold, it absorbs some gasoline. Once the engine warms up, this gasoline evaporates, causing an overly rich air-fuel mixture during idle, which leads to low-speed shaking. Throttle body: It is a controllable valve that regulates the air entering the engine, available in two types: traditional cable-operated and electronic throttle. The air entering the intake manifold mixes with gasoline to form a combustible mixture for combustion and power generation. Connected to the air filter at the top and the engine block at the bottom, it is often referred to as the throat of the car engine.