What causes significant shaking during BMW's auto start-stop function?
2 Answers
BMW auto start-stop function causes significant shaking due to the following reasons: Aging components: Engine ignition coils or spark plugs may experience insulation degradation from prolonged use, leading to insufficient ignition energy. This results in poor engine combustion and unstable operation, causing the engine to shake. The solution is to replace the damaged ignition coils or install a new set of spark plugs. BMW spark plugs should be replaced every 40,000 kilometers or 20,000 kilometers, depending on the engine model. Poor fuel quality: If the vehicle's engine uses low-quality fuel or operates frequently in stop-and-go city traffic without highway driving, excessive carbon deposits can accumulate inside the engine. These deposits absorb fuel from the intake and fuel injection systems, preventing the engine from reaching optimal performance and causing shaking. Regular cleaning of engine carbon deposits, throttle body, and fuel injectors is necessary to resolve this issue.
When driving my BMW, I noticed that the auto start-stop system causes particularly noticeable shaking when restarting the engine. This could be related to aging engine mounts or battery issues. Once the engine mounts soften, they can no longer absorb the vibration impact during start-stop cycles; a weak battery may cause difficulty in system activation, increasing the shaking sensation. Sometimes it's a software bug, such as sensors misjudging vehicle conditions and triggering abnormal starts. To address this, I recommend first checking whether the mounts are damaged or the battery voltage is low—routine maintenance with a voltmeter will suffice. Severe shaking affects driving comfort, especially during traffic jams where it becomes irritating; regular professional maintenance can prevent more expensive problems, such as accelerated component wear.
