How to check and eliminate the fault caused by exhaust pipe leakage in BMW 760Li?

BMW 760Li sedan, chassis model E65, equipped with N73 engine. Idle jitter, weak acceleration.
Diagnostic inspection: Perform fault diagnosis instrument detection, fault information shows that 2 cylinders are not working properly. Clear the fault code, restart the vehicle, and the fault code appears again. Continue to query the fault information of the DME2 control module, the content is that 8 cylinders are not working properly, and there is also a misfire fault. There are many reasons for the poor operation of the cylinder, involving multiple systems. After inspection, the fuel pressure is normal, and the ignition coil and spark plug are also normal.
Fault determination and elimination: Check the cylinder pressure and whether there is leakage. The structure of this engine is very complex, and the intake manifold must be disassembled to measure the cylinder pressure. During the inspection, it was found that the crankcase exhaust pipe was not plugged in firmly, which may cause the engine idle speed to be unstable. Re-plug it firmly and measure the pressure of each cylinder, all of which are normal. The fault is completely eliminated.
Engines with electronic valve devices are very sensitive to air leakage. This is because the intake volume is directly controlled by the intake valve, and the inside of the intake manifold is close to a vacuum. Once there is air leakage, it will affect the mixture and affect the combustion inside the cylinder, causing the engine to work poorly. When the engine control module recognizes this fault, it will be judged as a misfire fault to prevent damage to the three-way catalytic converter.