BMW 5 Series Cold Start Vibration
2 Answers
BMW 5 Series cold start vibration may be caused by the following reasons: 1. Engine management system malfunction: Such as incorrect coolant temperature or intake air temperature signals, wiring faults, etc. 2. Ignition system failure: Such as excessive spark plug carbon deposits or incorrect gap, high-voltage wire or distributor cap leakage, ignition coil damage, etc. 3. Fuel supply system failure: Such as injector nozzle sealing failure or blockage due to excessive internal carbon deposits. If the engine vibration disappears as the engine temperature rises, it may be caused by excessive spark plug carbon deposits, which are burned away as the intake air volume increases and temperature rises.
My BMW 5 Series used to shake badly during cold starts. At first, I thought it was a minor issue, but after some research, I found it was mostly due to carbon buildup—impurities accumulating inside the engine, affecting the air-fuel mixture; or aging spark plugs causing poor ignition; clogged fuel injectors or unstable fuel pump pressure could also be the culprits. I tried cleaning the throttle body and fuel injectors, and the improvement was noticeable. It took some time to do it myself, but I saved some money. I recommend checking the air filter and oil condition, and waiting a few seconds after a cold start before driving to reduce shaking. Don’t underestimate it—delaying repairs could lead to engine wear, making repairs more expensive. Regular maintenance is better for your car.
