What are the reasons for BMW car body shaking during startup?

[Daniela]

There are three main reasons for BMW car body shaking during startup. Below is a detailed introduction to these three reasons: 1. Severe carbon deposits: This may be due to a dirty throttle valve or excessive carbon deposits in the fuel injector and intake manifold. In cold conditions, carbon deposits can absorb some fuel, leading to incomplete combustion, which results in unstable idling and difficulty starting. The throttle valve or fuel system should be cleaned promptly. 2. Ignition system failure: When the ignition system is not working properly or the spark plug firing condition is poor, it can easily lead to such faults. Check if the spark plugs have excessive carbon deposits and replace them if necessary. 3. Unstable oil pressure: If you have already cleaned the engine carbon deposits, cleaned the throttle valve, replaced the oil pad and spark plugs, but still notice body shaking during idling, you should check whether the fuel supply pressure and intake pressure sensor are normal. When the fuel pump supply pressure is abnormal or the intake pressure sensor value is incorrect, it can easily cause body shaking.