What Causes Engine Shaking When Starting a BMW 5 Series?
2 Answers
BMW 5 Series engine shaking when starting may be caused by the following reasons: Engine Carbon Deposits: Severe engine shaking in a BMW 5 Series could be due to excessive carbon deposits in the engine. Excessive carbon buildup in the combustion chamber not only increases the compression ratio, creating high pressure, but also forms hot spots on the carbon deposit surfaces, leading to engine shaking. Clogged Fuel Injectors: Clogged fuel injectors can also cause engine shaking. The fuel injectors in electronic fuel injection vehicles are critical components for fuel delivery and have a long service life, potentially lasting hundreds of thousands of kilometers. However, gum deposits in gasoline can clog the injector nozzles, causing inconsistent fuel delivery from each injector. This inconsistency leads to uneven cylinder operation, resulting in engine shaking. The solution is to remove and clean the injectors.
The issue of BMW 5 Series shaking during ignition is frequently discussed in car owner groups. The main causes include ignition system and engine malfunctions. For example, if the spark plugs are aged or dirty, they may not provide sufficient energy to properly ignite the fuel during startup, causing the car to shake. Problems with the ignition coil are another factor—if the coil is faulty, the unstable current can lead to noticeable shaking, especially during cold starts. Severe engine carbon buildup is also a significant contributor; excessive carbon around the piston rings can affect cylinder sealing, leading to vibrations during ignition. The fuel system should also be inspected, as clogged fuel injectors or poor-quality gasoline can result in incomplete combustion of the air-fuel mixture. Additionally, loose or worn engine mounts can cause instability and shaking during ignition. It's recommended to start with the simplest fix—replacing the spark plugs with BMW-specific parts—then check the fuel filter and carbon buildup. Regular maintenance can prevent these issues, and during cold starts, allowing the engine to warm up for a few seconds before driving can help.
