What Causes a Jetta to Suddenly Start Shaking?
2 Answers
Generally, there are two main reasons for car shaking: one is engine power output vibration, and the other is vehicle body structure vibration. Power output vibration refers to issues with the coordination or independent operation of the engine and transmission, while vehicle structure vibration involves problems with the coordination of various components in the chassis suspension system. Engine power output vibration may be caused by carbon deposits, primarily on the spark plugs, throttle body, or inside the cylinders, leading to engine performance issues. The resulting shaking is mainly due to poor power output, and cleaning the engine internals may be considered. Shaking during gear shifts or when accelerating is often caused by aging engine mount shock absorbers. During gear shifts, the power output reduces balance, causing the engine to directly impact the vehicle body. Issues related to the chassis suspension system should be addressed by a repair shop, as there are many components involved. For example, aging rubber bushings can also lead to car shaking.
I encountered a similar situation last time I drove my Jetta - it suddenly started shaking violently, even the steering wheel was vibrating. The most likely issues are in the engine compartment, such as aging spark plugs causing poor ignition. Misfiring cylinders will lead to noticeable shaking. Also check the engine mount bushings - when these age and crack over time, they lose their damping effect, allowing all the engine vibrations to transmit into the cabin. Fuel system problems could be another cause, like clogged fuel injectors or a gasoline filter that hasn't been changed for too long, leading to poor fuel delivery. In my case, replacing all four spark plugs fixed it immediately. I suggest focusing your troubleshooting on these areas, and pay special attention to whether the shaking is more noticeable during acceleration or at idle, as this helps significantly in diagnosing the fault point.
