The mileage is about 25 thousand km, with 2013 KIA K2 cars equipped with 1.6 engines and automatic transmission. Users reflect: the engine jitter, acceleration is weak, engine fault lights are lit. Fault diagnosis: the car suddenly appeared in the driving engine jitter and engine fault lights on the problem, engine fault lights at the same time appeared to speed up the situation. Because the location of the car's fault was very close to my shop, the customer drove the car to my shop for repair. After the repair technician first opens the engine cover and starts the engine, it is found that the engine is shaking very seriously at the idle speed, then the acceleration pedal is stepped down, the engine speed is obviously able to feel the "sudden" during the rising of the engine, and we can preliminarily judge the possibility of the engine. In the problem of the lack of cylinder. The maintenance technician then uses the diagnostic apparatus to diagnose the engine control system self. The read fault code is P0300 perception irregular fire, and the P0302 sensing No. 2 cylinder loses fire. The fault code can be deleted at that time, but after restarting the engine and running for dozens of seconds, the fault code P0302 will appear again, and the engine will shake again. According to the frequency of the fault code, we can judge that the ignition of the 2 cylinder failed or that the ignition could not be normal. The causes of engine misfire usually include spark plugs, ignition coils, cylinder pressure, fuel injectors and fuel pressure. When maintenance technicians are troubleshooting fire accidents, they often think of ignition systems. So in the maintenance of the car, the maintenance technicians start with the ignition system first. The engine of the KIA K2 model has applied the independent ignition system. Each cylinder has an independent ignition coil. The ignition coil is supplied by the main relay of the engine control system, and the generator ECU controls the primary circuit of the ignition coil. Because the fault code has always reflected the 2 cylinder fire, the maintenance technician in the maintenance of the fault, the 2 cylinder ignition coil and the 1 cylinder ignition coil, and then start the engine, after the engine has been running for dozens of seconds after the jitter well and the engine fault lights light. At this time, the fault code read by the diagnostic instrument becomes P0301 aware of the 1 cylinder fire. The method of adjusting the ignition coil proves that the ignition coil of the No. 2 cylinder has been damaged, and the replacement of a new ignition coil is installed into the No. 2 cylinder, and the engine will no longer shake and the fault is ruled out after the engine is started.