The mileage is about 105 thousand km, the new Elysee comfort car equipped with automatic transmission. User response: the engine suddenly stalled while driving. After restarting, the vehicle can be normal. However, it is not long before the flameout fault occurs, and the interval between extinction becomes shorter. Fault diagnosis: (1) the engine control system of the car is read by PROXIA 3 diagnostic instrument, and no information about the failure of the engine is not obtained. (2) using the special diagnostic wiring harness of the ME7. 4.4 EFI system to check the components and lines of the EFI system. Check the resistance of engine speed position sensor, normal. Continue to check the feedback waveform of the engine speed position sensor, there is no abnormal situation, eliminate the possibility of engine speed sensor fault location. Check the voltage of the power supply foot and the iron foot of the engine control unit. The measured results are respectively the battery voltage and 0V, which meet the normal standard. Check the working state of the injector of the 4 cylinder of the engine, and clean and detect the 4 injectors. The fuel pump and fuel line were inspected and no bad condition was found. The above inspection results show that the engine fuel supply system works normally. Check the status of the engine intake pressure sensor and its circuit, and everything is normal. Check the operating conditions of the electronic throttle body in the engine control system, when the engine is running and the engine is flameout (the ignition switch hits the M bit), and uses a multimeter to measure the power supply foot of the electronic throttle motor, the tie foot, the throttle position sensor, the leg, the No. 1 signal feedback foot, and the number 2 letter. The voltage value of the foot is fed back, and there is no problem. Continue to use the oscilloscope function in the diagnostic instrument to read the waveform of the feedback signal, and the result is normal. This eliminates the electronic throttle body and its related lines. (4) check the work of carbon tank and emission solenoid valve and related line to meet the requirements, 5 because it is automatic transmission model, and there is information connection between the engine control unit and automatic transmission control unit, which can affect the normal work of each system. Yu Shijian check the automatic transmission control unit and its correlation. Line. The fault of the automatic transmission control unit is read by the diagnostic instrument without any fault information. The voltage and resistance of every working foot of automatic transmission and automatic transmission control unit are checked, and everything is normal. The above results exclude the possibility of automatic transmission problems. Check the relevant condition of the engine anti start system. First of all, under the condition of engine operation, the PROXIA3 diagnostic instrument is used to carry out the parameter measurement operation of the engine anti start system, and the results meet the requirements. When engine failure occurs, it continues to measure parameters and finds that the key code has not been received. According to this information, it is considered that there may be some problems with the anti startup control box, the engine control unit, the key and the coil and their wiring. To check the above parts and related lines, the whole replacement operation is carried out for the 3 components on the same model car, which is on the same model, which is on the same model of the same model without fault. The fault still exists, indicating that the fault is related to the line of the anti start system. Continue to check the line, use the multimeter to measure the resistance of the coil, found that there are two cases of normal value and circuit breakage inside the coil, so a new coil is replaced, and the fault is completely disappearing. Fault dimension summary: the detection of the fault parts, the coil has a section of the existence of virtual connection, resulting in the normal work of the coil (the coil internal loop, and sometimes the normal circuit breaker). When the coil is broken, the answer device in the key can not pass the information through the coil to the anti start control box. The engine control unit is in the lock state at this time, and the engine will suddenly extinguish. Sometimes the internal circuit of the coil is normal. Under this condition, the information transmission between the engine control unit and the key and the anti startup control box is in a normal state. The engine control unit is in the unlocked state when the transponder is successful with the anti start control box, the anti start control box and the engine control unit, and the engine is able to operate normally.