The 6-year-old BMW 320 is short of cylinders, and its recent working conditions are not good. After cleaning the air intake and throttle valve, it is found that the cylinder is missing, and the spark

The 6-year-old BMW 320 is short of cylinders, and its recent working conditions are not good. After cleaning the air intake and throttle valve, it is found that the cylinder is missing, and the spark plug and igniter are normal. How to determine the missing cylinder? How do you know that the spark plug is working properly when the cylinder is missing? Has the spark plug suspected of leaking cylinder been interchanged with the spark plug of the adjacent cylinder?

After confirming the lack of cylinder, I think you should check the fuel injection of the cylinder. Is the nozzle of the cylinder in good working condition? If the fuel injector is good, do you want to check the intake and exhaust valves of the cylinder? For example, is there carbon deposition?

I don't know if the knock sensor works, but I think you should check it, too. As for the normal discharge after the cylinder is missing, I think this is the automatic protection function of the computer, and the fuel injection to the cylinder has stopped. If the cylinder does not work well, resulting in incomplete gasoline entering the exhaust pipe, then incomplete gasoline will continue to burn in the three-way catalyst. If the time is not too long, the temperature of the three-way catalyst will be very high, and too high temperature will lead to the destruction of the three-way catalyst. Therefore, measures to stop fuel injection are implemented, which is a protective measure to protect the three-way catalytic converter.