FAW TOYOTA crown limousine in 2012 with a mileage of about 26 thousand km. User response: sometimes the vehicle will be accelerated for 30 km or more. Through communication with the customers, the maintenance staff learned that the vehicle had eliminated the leakage of the coolant caused by the loose pipe hoop, resulting in the failure of the vehicle to extinguish during the driving due to the high temperature of the coolant. Inspection and analysis: the vehicle is normal in the process of coming to the shop. The maintenance personnel try to check the vehicle control system with the IT2 fault diagnosis instrument after receiving the car, and no fault code is found. Observe the water temperature in the dashboard display is normal, open the engine cover and observe the coolant capacity is normal. The maintenance personnel were tested in connection with the IT2 fault diagnosis instrument. When the vehicle was running continuously for 30 km, the customer described the malfunction again. Under the condition that the vehicle is unable to accelerate, the data flow of Wu Ji Lu fault is diagnosed by IT2 fault diagnosis, which shows that the intake volume and fuel injection pulse width are abnormal. The maintenance personnel opened the engine hatch cover and found that the surface of the engine control unit was a bit hot. At this time the temperature of the environment was 35 degrees centigrade. What was the reason why the surface of the engine control unit was found to be 70? After careful examination, it was found that the air vent of the engine control unit fell off, and then the vehicle was installed. But when the vehicle was running for 35km continuously, the acceleration of the weakness was also repeated. Two maintenance personnel had to repeat the test to analyze the failure phenomenon. When the vehicle was running for 80km, the IT2 fault diagnosis instrument showed that the vehicle had P0174 fault code. The meaning of the fault code is that the 2 column of the cylinder is too thin. Before this, the assumed judgment was overthrown by the maintenance personnel to test the fuel oil meter. When the failure occurred again, the fuel pressure was observed. The fuel pressure of the failure occurred less than 100 kPa, obviously this was abnormal. The maintenance personnel removed the fuel filter for inspection and found that the dirt was serious. This is the real reason for the acceleration of weakness after running for a period of time. Troubleshooting: Troubleshooting after replacing fuel filter and cleaning fuel supply system. Review and summary: the seemingly simple fault also made the maintenance personnel brain drain because the maintenance personnel were interfered by other factors. Facts have proved that the necessary data analysis and indomitable spirit are essential for vehicle maintenance. Maintenance personnel should broaden their minds and not be trapped by some factors.