What Causes Idle Vibration in a New A6?
2 Answers
Introduction to the causes of idle vibration in a new A6: 1. Unstable Oil Pressure: Abnormal fuel pump supply pressure or incorrect readings from the intake pressure sensor can cause body vibration. Owners should check the oil pressure and replace components if necessary. 2. Shock Absorption System: The engine mount is essentially the shock absorption system of the engine. If the engine mount is faulty, vibrations can be transmitted to the steering wheel and the cabin, causing idle vibration. 3. Severe Engine Carbon Buildup: After driving for a certain mileage, a dirty throttle valve may fail to close properly or the idle motor may become stuck, leading to higher engine idle speed. Carbon buildup during this process causes vehicle vibration, especially noticeable when starting the engine, which may shake more than usual. It is important to clean carbon deposits promptly. 4. Ignition System Issues: During cold starts, the engine requires a richer air-fuel mixture and higher ignition energy. If the spark plug gap is too wide, or if the ignition coil or high-voltage coil is aging, ignition energy may decrease, resulting in body vibration. Inspect the spark plugs and distributor wires, and adjust or replace them if necessary.
As someone who frequently repairs cars, idle shaking is quite rare in new cars, but not unheard of. Possible causes include issues with the engine's ignition system, such as loose or prematurely aged spark plugs. Even though the car is new, assembly quality can vary. The fuel system is another culprit—if the fuel injectors are clogged or the fuel pump delivers unstable pressure, the engine RPM becomes uneven, leading to shaking. Additionally, a poorly installed or leaking air filter can cause fluctuations in air intake, resulting in the same issue. During the break-in period of a new car, loose engine mounts or transmission mounting bolts can transmit vibrations directly to the body. Throttle body dirt buildup or faulty computer sensor readings may also be to blame. I recommend checking the dashboard warning lights and trying a simple test: drive at high speed for a few minutes. If the shaking disappears, it might be a software calibration issue; otherwise, visit the dealership immediately—repairs are usually free under warranty, saving you hassle. Don’t ignore idle shaking, as it can affect engine longevity over time.
