A Honda flying car with a mileage of about 100 thousand km in 2005. User response: after the vehicle was put into reverse gear, the engine was jitter drastically, the speed decreased obviously, and the noise of "ga la ga la" was emitted from the engine room. If the air conditioner is opened at this time, the symptoms are more obvious. Fault diagnosis: the analysis may be caused by the loosening or damage of the cooling fan coil, the breakage or damage of the damping spring in the flywheel, failure of the components of the starting clutch (including friction plates, steel plates, piston and O rings), failure of the parts of the reverse gear brake, and the CVT transmission control system. Malfunction and so on. Start the engine again, turn on the air conditioner and hang the reverse gear to reappear the fault. At the same time, open the engine room cover and look for the sound source. After checking, the cooling fan ring and motor are working normally without loosening or damage. The lifting vehicle was searched for the sound source from the middle part of the body. After examination, no abnormalities were found in the connections between the engine and the transmission and the body. It is doubted that the damping spring in the flywheel is broken or damaged, and the transmission is separated from the engine, and the flywheel is dismantled carefully to find that the damping spring is intact. No problems were found in the above inspections, so they decided to dismantle the CVT transmission. After carefully disassembling the components of the CVT transmission, it is found that all parts of the clutch are normal, and all parts of the reverse gear clutch are regular. No obvious faults were found after the transmission was removed, so the parts of the transmission were thoroughly cleaned and assembled again. After testing the gearbox after loading, it was found that the symptoms disappeared when the car was cool, and the trouble remained after the hot car. After careful consulting the data and communicating with the peers, the analysis may be the error of the control program for the start clutch of the ECM/PCM, which leads to the failure of ECM/PCM to effectively control the engagement and separation of the starting clutch, so the road test for the starting clutch of the vehicle is carried out according to the method in the maintenance manual.