In the Fourth Era of China, electronically controlled high-pressure common rail engine has become the mainstream. Because of the addition of electronic control, there are many problems in the circuit, and the maintenance is not very convenient. This puts forward high requirements for maintenance personnel. The previous extensive maintenance is no longer suitable for the current situation.
A truck crane equipped with Xichai 6df3-22e engine had the fault that the engine power was limited and the speed could only reach 1500. After changing several batches, the maintenance personnel did not repair it. Forum users “crazy coax random explosion” received a call for help and immediately sent someone to repair. However, on the first day, after all the hardware were inspected and the parts that need to be replaced were replaced, the fault remained. The read data stream is still the trigger value of the fuel metering unit is unstable. After the dispatched personnel came back in the evening, they analyzed the problem together and discussed how to solve it. The main reason should be the circuit.
After discussion, I decided to continue the maintenance the next morning. When I arrived at the store, I arranged what I needed to bring, including a set of diesel filter elements and an ECU. I brushed the ECU, computer, multimeter, circuit diagram, wires and various plugs. I was ready to go on the road. Before departure, call the car owner and ask them to charge the battery to ensure sufficient power.
Before arriving at the car, first install the fuel injection nozzle removed yesterday, and replace the full set of diesel filter. The failure of the car is still the same. In fact, in itself, this problem is generally not an ECU problem, but up to now, we can only eliminate the hardware first, so replace the ECU. As it is a construction machinery program, the original vehicle data must be copied first and then written to the new ECU. The fault remains after startup. It has been proved that it is a circuit fault, and it is a small fault, but the line needs to be cleaned gradually. The crane has been for 5 years, and the line is very miscellaneous and chaotic.
After checking the line from ECU for more than an hour, I didn’t find any damage. Finally, I glanced at the plug-in wire of the metering unit inadvertently. You should be able to see that this line was externally connected later. It is a detail that doesn’t attract people’s attention, but often such an unnoticed detail is the problem. This line was broken before, and the electrician reconnected it.
This is the connector of the metering unit. The waterproof protective cover inside is gone. If the waterproof protective cover inside the plug is not removed, it is difficult for the plug to be inserted. Many repairmen remove the waterproof cover to save trouble. As a result, there is such a problem. It is really difficult for you to find out.
In order to verify the problem, I took a new one and started the test run. After starting the car, first use the decoder to clear the fault code, and then look at the data flow. The trigger value is finally stable. After reading the data, I know it clearly, and the fault is eliminated. The speed of one foot accelerator is 2500 rpm. When it is released, it is still 2500 rpm. Then release the pedal and continue to rotate at 2500 rpm. The accelerator is stable and there is no loss of speed. The test is still the same when the engine is turned off. After repeated tests, the car returns to normal.
This is the fault because the former repairman was not meticulous in the maintenance process. Due to the small operating space of the crane, it was difficult to plug in the waterproof sleeve on the plug. The repairman removed the waterproof sleeve and plugged it in, resulting in the loosening of the plug for a long time. The forum user “coax and explode” is not the case. He is a very meticulous maintenance personnel. Although he finally solved the problem with the most primitive exclusion method, his meticulous and serious attitude is worth learning by the majority of maintenance personnel. The value of high-level maintenance personnel is reflected in these places. Are you willing to be a high-level or traditional extensive maintenance personnel?
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