What Causes the Abnormal Noise When Accelerating a BMW 7 Series?
2 Answers
BMW 7 Series acceleration with abnormal noise reasons are as follows: Positioning Valve Function Failure: The mechanic used a computer to detect the transmission system, and the fault code displayed 400671 positioning valve function failure. The mechanic explained that this is due to excessive mileage of the transmission, causing wear on the transmission valve body and abnormal oil pressure. When replacing the new transmission fluid, sudden pressure fluctuations triggered this fault. The vehicle's fault is due to abnormal wear on the transmission valve body. Changing the transmission fluid was just a trigger; the actual fault lies in the wear of the transmission valve body, leading to abnormal oil pressure fluctuations. Solution: Lift the vehicle and drain the transmission fluid. Remove the transmission oil pan, separate the transmission valve body from the computer, and upgrade and process the transmission valve body separately.
Acceleration-related noises are quite common in BMW 7 Series. Having driven such vehicles, I can say the noise might stem from issues with the engine belt—like an aging belt that squeals when tightened during acceleration. Alternatively, a worn-out belt tensioner could throw the system off balance, generating noise. Additionally, if the engine mounts have deteriorated, the vibrations from acceleration can cause body components to rub against each other, resulting in clicking or rattling sounds. Loose exhaust system bolts might also rattle and clang when accelerating. My advice is not to delay addressing these noises, as prolonged neglect could lead to bigger issues, such as a snapped belt causing engine damage. The best course of action is to promptly take the car to a professional repair shop for diagnostics—using computer tools to pinpoint the exact cause before replacing parts. BMWs require meticulous maintenance; regular checks of belts and mounts can prevent such annoyances.
