What Causes the BMW 740 to Shake During Rapid Acceleration?
2 Answers
Reasons for the BMW 740 shaking during rapid acceleration: Severe Engine Carbon Buildup: The most common cause of car shaking is a dirty throttle body or excessive carbon buildup in the fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts and making it difficult to start. In this situation, the car will only start easily once the carbon deposits have absorbed enough gasoline to reach saturation. After starting, the gasoline adsorbed on the carbon deposits is then drawn into the combustion chamber by the engine's vacuum suction, causing the air-fuel mixture to become too rich. The engine's combustible mixture alternates between being too lean and too rich, leading to idle shaking after a cold start. Ignition System Issues: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance in the ignition system or inadequate spark plug firing can also cause this type of problem. Unstable Fuel Pressure: If you have already cleaned the engine carbon deposits, throttle body, replaced the fuel gasket and spark plugs, but still notice the car shaking at idle, it is recommended to visit a 4S shop to check whether the fuel supply pressure and intake pressure sensor are functioning properly. Abnormal fuel pump pressure or incorrect readings and poor performance of the intake pressure sensor can also cause the car to shake.
When I accelerate hard in my BMW 740, it shakes, which is really annoying. Based on experience, the shaking is mainly caused by issues in the ignition system or engine mounts. Worn or eroded spark plugs can lead to uneven ignition, causing unstable combustion during hard acceleration. Poor contact or loosening of ignition coils can also trigger strong vibrations. Additionally, aging or cracked rubber in engine mounts fails to dampen engine vibrations, especially noticeable under high power. Fuel system problems, such as insufficient supply from the low-pressure fuel pump or clogged injectors, can disrupt the air-fuel ratio. Carbon buildup in the throttle body or cylinders also affects combustion stability. Ignoring such shaking can impact performance and safety. I recommend first visually inspecting the mounts for damage, then checking fuel pressure or reading OBD fault codes. Don’t wait until it causes trouble at high speeds. Regular carbon cleaning can prevent issues before they arise.
