(1) Failure phenomenon: an official website of China National Heavy Duty Truck JNll7l 6130Q used cars diesel engine, there is the phenomenon of weak driving. Flat on the road at high speed in the past to achieve 80hkh, now can only reach 40 ~ 50km / h. In the past with the third gear to climb the steep slope, and now must use a file or two files Caixing. (2) Fault diagnosis excluded: the beginning, this phenomenon mistaken for bad cylinder seals, piston ring wear due to severe. However, after replacement of piston rings cylinder boring, still not improve. Finally, after a comprehensive analysis on the reasons that the following aspects will lead to the failure. ① Official website of China National Heavy Duty Truck Diesel Engine intake system resistance increases. Normal diesel engine, the cylinder into the air more than the end of compression pressure and temperature increased, the rapid combustion, engine torque and power is also large. If the air filter resistance increases, the intake valve through the cross section at small, it will reduce the cylinder into the air and affect the engine torque and power. In the maintenance of the oil bath air filter, if not clean the filter cleaning, and to raise the oil inside the air filter too, which will increase the intake resistance. Some research institutes test proved that the surface covered with dust filter, the diesel will drop 24% maximum power, maximum torque down 24.6%. In addition, if the valve clearance adjusted properly, will affect the level of valve lift or valve timing is not accurate, will also affect the cylinder into the gas. ② Poor quality oil. Official website of China diesel heavy truck work, such as the oil shortage, inability to make diesel engines for power. The causes of insufficient oil supply, in addition to pump fuel supply to adjust properly, unable to adapt to various engine operating conditions, the Practice has proved that poor oil supply, but also lead to a common cause of failure of this one. The reasons for oil block, multi-line fuel filter into the oil filter and fuel pump inlet valve between the mouth to filter too dirty, the filter is clogged. Also some diesel without precipitation, by adding the use of the fuel tank caused. Diesel engine fuel injection timing, diesel engine performance has a great influence. Fuel injection timing is too small, the ignition delay time accordingly, even in the dead only after burning. Since the combustion process lag, combustion period is extended, the maximum combustion pressure is reduced, the thermal efficiency decreased significantly, which makes car driving weakness. In addition, if the injection pressure fuel injectors reduce injection atomization of poor quality, or the injector needle and the needle valve body sealing cone poor mixture formation were also cause undesirable, resulting in deterioration of leaving the combustion process Diesel engine power reduced. Based on the above analysis, the official website of China National Heavy Duty Truck Diesel Engine Fault is the real reason for the air cleaner element plugged. For the new filter after troubleshooting.