Injector malfunction causes difficulty in starting excavator engine

One customerDaewoo DH220-7The engine has difficulty starting and the speed is unstable after starting. The machine emits black smoke at high speeds. There is slight black smoke when operating the machine at low speeds, and the machine should be turned off when operating at high speeds.

Cause analysis:

Using data cable detection, it was found that:
1. Unstable engine speed
2. When the machine does not automatically shut down, the suction pressure and common rail pressure are relatively normal. When the machine is loaded at high speed, the suction pressure will instantly rise above 170MPa, and the engine will automatically shut down.
3. Check that the compensation values of the injector are normal (within plus or minus 0.8)
Based on the above situation, it is speculated that it is caused by poor pressure limiting valves or common rail pressure sensors on the common rail. So the common rail was replaced, but the test malfunction still persists. After reporting the fault symptoms and collected data to the company, it was believed that it may be caused by a faulty SCV valve. After replacing the SCV valve, the fault symptoms persisted. Then suspicion arose that it was a problem with the injector. After replacing the injector, the fault was eliminated.

Solution:

Ultimately, the malfunction was resolved after replacing the injector
Due to some unclear controls in the common rail system. For example, how does the ECU determine and make control decisions when collecting data on common rail pressure, diesel temperature, and suction pressure. So analyzing the data collected by the DX program can easily lead to errors. I hope the company can provide more information and cases in this area to improve its ability to solve faults in the common rail system.