The method of replacing the spark plug is: firstly, clean the dust and oil pollution near the high-voltage line pile head, and then unscrew the fixing screw of the high-voltage line pile head with a sleeve. The pile heads of some high-voltage lines may be tight. If this is the case, it is necessary to swing from side to side and operate slowly, otherwise it is easy to break the high-voltage line. After removing the high-voltage wire pile head, loosen the spark plug with the sleeve, be careful not to let dust enter the combustion chamber, and keep it clean, dry and free of oil pollution, otherwise it will cause air leakage and spark weakening. Next, insert the hose on the pile head of the high-pressure pipeline into the combustion chamber and pull out the spark plug. Please note that after removing a spark plug in this process, install a new spark plug and replace it one by one, instead of removing all of them and installing them together. When installing, aim the spark plug at the threaded hole with sleeve, screw it in gently by hand, screw it to about half of the total thread length, and then tighten it with sleeve. After the spark plug is plugged in, it is fixed on the pile head of the high-voltage line, and the internal buckle clamps the spark plug. After installing the spark plug, if you screw it with an ordinary socket, you don't need a torque wrench. As long as it feels tight, you don't need to twist it hard, otherwise it will be easy to twist the screw. When tightening the spark plug, pay attention to straightening the wrench as far as possible, so as to avoid the part outside the rubber ring of the wrench touching the tail of the spark plug and causing damage to the insulating porcelain. When installing the ignition coil, be careful not to make mistakes, and install it according to each cylinder. Of course, the high-voltage wire length of each ignition coil is different, so be careful.