【Fault description】
    Automatic transmission shift, the speed fluctuated, the engine speed at 4000r / min, the speed can reach 100km / h.
    【Inspection process】
    The engine speed of 400Or / min, speed to reach 100km / h, indicating that the automatic transmission did not enter the 4-speed drive, so the transmission assembly overhaul, check the transmission inside the friction plate, brake belt and oil seal and so good, did not find any problems. The initial suspect fault occurred in the transmission body assembly, so the valve body assembly to open the cleaning, the transmission re-assembly after the test, the fault remains the same. At this time on the fault again re-analysis, that failure does not necessarily appear in the transmission, there may be insufficient engine power, torque is not enough, so that the transmission shift, resulting in high and low speed, and can not rise to 4 files. Then the engine to repair, first clean the engine oil, and extract the engine fault code, fault code display: air flow meter line problems, measuring the flow meter external lines normal, unplug the flowmeter plug test (the engine can not take the air flow meter Signal, automatic failure protection), then, the vehicle shift strong. 2500r / min when the speed reaches 100km / h, the transmission can enter the fourth gear, to determine the air flow meter problem.