Is it normal for the BMW 7 Series engine to shake a few times when starting?

[VonDerek]

It is normal for the BMW 7 Series engine to shake a few times when starting, but if the shaking persists, it is abnormal and the cause should be identified and resolved in a timely manner. Taking the 2017 BMW 7 Series as an example, it belongs to the large car category with the following dimensions: length 5250mm, width 1902mm, height 1498mm, wheelbase 3210mm, fuel tank capacity 46l, trunk capacity 420l, and curb weight 2190kg. The 2017 BMW 7 Series is equipped with a 2.0t turbocharged engine, delivering a maximum horsepower of 258ps, maximum power of 190kw, maximum torque of 400nm, paired with an 8-speed automatic transmission.

[VanBrandon]

Having worked at a BMW 4S dealership for many years, I've encountered numerous 7 Series owners inquiring about engine shaking during startup. In fact, slight shaking during cold starts is quite common, especially in low temperatures. This occurs because the thicker engine oil requires time to build pressure, during which the ECU controls additional fuel injection to raise RPM, causing brief vibrations. It's generally fine if the RPM normalizes within ten seconds. However, if accompanied by metallic clanking sounds or dashboard warning lights, immediate attention is needed. Last week, a 740Li owner discovered aged engine mounts during maintenance, causing noticeable vibrations transmitted to the chassis. For such luxury vehicles, I recommend biennial inspections of ignition systems and suspension support components, as severe shaking may impact air suspension and transmission longevity.

[SanMila]

I used to drive an older 730Li, and it did vibrate a few times when starting up in the garage during winter. This kind of shaking is quite common in turbocharged engines, mainly because the fuel-air mixture isn't stable at startup. BMW engineers have mentioned that direct injection systems can amplify this phenomenon. As long as the RPM stabilizes around 800, it indicates the system is functioning normally. However, if the shaking persists or recurs after the engine reaches operating temperature, it's likely a high-pressure fuel pump or electronic throttle issue. Once before a road trip, I discovered excessive spark plug gaps during inspection, which nearly caused a misfire. The new 7 Series with 48V mild hybrid technology now has significantly reduced startup vibrations.

[VonJulia]

Having driven three generations of BMW 7 Series, I believe cold start shaking depends on the season. When the garage temperature is below zero in winter, the vibration is more noticeable in the first few seconds after starting, which is a normal response as the engine warms up quickly. BMW's inline-six engines are inherently smooth, but if you also smell gasoline or see black smoke from the exhaust, it might indicate clogged fuel injectors. During my last maintenance, carbon buildup in the intake manifold was found to worsen this phenomenon. Daily driving habits are crucial—avoid using low-grade fuel regularly, and periodic cylinder cleaning can significantly alleviate the issue. Now, my 750Li is four years old, and it still maintains a slight vibration for about two seconds upon each startup.