The liberation tractor of the overload king of forum card friends has been transporting coal from Zhangjiakou, Hebei to Tianjin, and has been operating on this line for many years. The king of overload has never been careless in the maintenance of the car. He has always used dafite filter and modified two-stage air filter. The car has been doing well in the past four years, but the power of the car has been significantly lower than before in the past six months, and black smoke has accelerated. So we decided to go to SongGe, Qingxian County to repair the vehicle. We also broadcast the repair process live of EFI.
The computer diagnoses and reads the data. The injection advance angle of the original vehicle is 1.0ca, and the closing timing of the oil pump PCV is 129ca. The closing timing of oil pump PCV is obviously low, and the normal data should be about 146ca. Next, for the unit Ca, CA should be the English abbreviation of crank angle. In general, the crankshaft angle is often expressed in ° Ca, that is, 1 ° CA represents one degree in 360 degrees of crankshaft rotation. Generally, it is 0 ° CA when the piston moves to TDC.
Then the car was raised to disassemble the PCV valve. After disassembly, the PCV valve was disassembled for maintenance. During the period, the internal valve plate of PCV valve was slightly worn. The worn valve plate will lead to large oil return and slow rise of rail pressure. After repair, the retest vehicle was installed, and the PCV valve data did not rise significantly. Troubleshoot the PCV valve itself.
Then remove the fuel injector and fuel injector jumper pipe to check whether there is internal leakage. Then, it was found that the ends of the jumper pipes of the six fuel injectors of the vehicle were damaged. It is suspected that the maintenance personnel were disorderly in the installation process, resulting in the damage of the jumper pipes. At the same time, check the fuel injector and it is in good condition. After reassembly, the data has not increased significantly.
Then, it is suspected that there is a problem in the low-pressure oil circuit. Disassemble the low-pressure oil return screw and directly supply oil to the fuel injector. The data has not increased significantly.
Disassemble the common rail pressure sensor and test it. The common rail pressure sensor is normal.
The gasket of the exhaust pipe with air leakage and damage and the snap ring at the pipe joint were replaced.
According to our analysis, the hardware of high-pressure oil pump and PCV valve are normal without failure. It is analyzed that the electrical common rail system of 6dl1 is provided with timing signal by two different systems. The crankshaft position sensor of flywheel position provides fuel injection timing signal to ECU computer, and one is located on the oil pump to provide fuel injection timing signal. First disconnect the connecting plug on the high-pressure oil pump and find that the data is restored to 138 close to 140. Then plug in all the plugs, disconnect the crankshaft position sensor and find that there is no change in the data flow. The fault point at this position is gradually clear!
So why are the signals different? We analyzed that the car has been running for more than four years, and the gap may have been worn out in the middle of the timing gear, resulting in the deviation of the signal transmitted to the high-pressure oil pump. To be exact, it should be lagging! Next, we come up with two schemes to verify whether the judgment is correct. First, the fixed hole of the connecting flange of the high-pressure oil pump is processed into an elliptical hole with adjustable deflection. If the original hole is round, it cannot be adjusted; Second, drive the oil pump gear forward one tooth in advance! Later, the second scheme with small difficulty coefficient was selected to remove the fault.
Finally, a climbing program with an advance angle of 6 degrees is written on the computer of the vehicle’s electronic engine, so as to further improve the vehicle power. Then, the power lifting and tail gas of the test run are satisfactory, and the whole maintenance process is over.
In the whole maintenance process, first judge whether the PCV valve itself is normal according to the data flow itself, and then gradually eliminate the faults of fuel injector, crossover pipe and low-pressure oil circuit until the problem is finally solved. The whole process can be described as going through twists and turns. From this failure case, it is not difficult for us to understand that EFI maintenance is not terrible. As long as we can master knowledge, correct logical judgment thinking, rigorous maintenance technology and professional maintenance equipment, these problems will eventually be solved. At the same time, the owner’s spirit of careful maintenance of the car is also worth learning.