Changan CS75

The car has a single part with a front-right fender spray. The engine is positioned normally. The car's mileage is 374,000 km. There is an engine misfire issue—I'm not sure what it is. I took it to several people, including specialists familiar with Chinese vehicles, and they said the ignition is cut off from one of the spark plugs. Until now, I haven't identified the solution—even after replacing the ECU with a new one.