Unplug the wiring harness of ignition coil and remove the fixing bolt of ignition coil; Check the spark plug (check whether the terminal is damaged, check whether the insulator is broken, check whether the electrode is worn, etc.); Select the appropriate tool, assemble the tool, disassemble the spark plug, and remove the spark plug one by one; Cover the spark plug holes on the cylinder with a cleaning cloth to prevent objects from entering the cylinder