What is the reason for resonance around 1200 RPM in a BMW 5 Series?
2 Answers
Tire tread wear and unevenness can cause resonance sounds due to friction and impact between the tire and the ground, which are transmitted into the cabin along with vibrations from the fender and mudguard. In this case, soundproofing materials should be added to areas such as the doors, fenders, and mudguards to reduce noise. More related information is as follows: 1. If the car engine shakes severely while driving and sometimes fails to start, it may be due to a dirty throttle or excessive carbon buildup in the fuel injector and intake manifold. In cold conditions, carbon deposits can absorb some fuel, and if the fuel does not fully enter the cylinder for combustion, it can cause unstable idling and difficulty starting. 2. When driving at a certain speed on the highway, the steering wheel may noticeably shake or vibrate, but this is not obvious at low speeds. In fact, there are many reasons for engine shaking. Here, we first need to rule out abnormal shaking caused by engine faults, as engine issues usually also occur at low speeds.
This resonance issue is quite common in the BMW 5 Series. I suspect it originates from the engine, as the 1200 rpm range is typically a low-speed interval where the engine might not be well balanced. For example, the inline-six engine inherently has its own natural vibration frequency. If there's uneven ignition in a cylinder or slightly dirty fuel injectors, it can cause minor vibrations. Coupled with aging chassis components, such as hardened engine mounts or transmission support rubber, the resonance can amplify. Additionally, if the exhaust pipe's hangers are loose or rusted, airflow impact at this rpm might produce a buzzing sound. I recommend avoiding long trips for now and finding a reliable repair shop to check the sensor data. If it turns out to be an issue with the spark plugs or fuel injection system, it could easily lead to more faults. For prevention, regularly inspect these rubber components during maintenance and keep them lubricated to extend their lifespan.
