A mileage of about 70 thousand km, carrying the Chery engine's Chery QQ car in 2011. User reflection: it is difficult to start the car cold car. Inspection and analysis: the maintenance personnel put the car to test the car after one night. The temperature reached - 14, and the temperature of the coolant was - 16 C, which was in line with the failure conditions described by the user. When the engine is running, when the engine speed reaches 181 r/min, it is found that the air pressure in the intake manifold does not change significantly, and the throttle opening at this time is 23 degrees. In this case, if the engine can pump normally, the air pressure in the intake manifold should be reduced. Further observation also found that although the ignition timing was accurate, the fuel injection signal was not delivered. The analysis shows that the engine control unit does not send fuel injection signals because the intake volume is 0 g/s. Since the engine speed can exceed 150 r/min, there is no problem with the piston and crankshaft. The low bending part of the exhaust pipe is heated by the gas cutting gun, then the engine is started and the water is ejected from the exhaust pipe. After the cooling solution reaches the normal temperature, the data flow of the engine idle speed is observed and the parameters are normal, which indicates that the engine itself has no problem, but the water deposition in the exhaust pipe causes the above failure in the lower bend of the exhaust pipe. Troubleshooting: the minimum point of the exhaust pipe is drilled by a electric drill with a diameter of 2 mm diameter, so that when the car hot car is stopped, the water will be discharged from here, and it will not form ice again. After a day's trial run, the engine started smoothly and the problem was solved thoroughly.