Poor EGR valve leads to black smoke emission from Shengang SK200

A certain customer'sKobelco SK200 ExcavatorContinuously emitting black smoke at work; Especially when the hydraulic pump overflows, the engine emits thicker and longer lasting black smoke. The operator reported that the engine suddenly emitted black smoke during machine operation.

Cause analysis:

Firstly, inspect the oil circuit and intake air; No abnormalities were found in the diesel filter, oil-water separator filter, air filter, and turbocharger.
2. Remove the SCV valve and check for any abnormalities. After cleaning, the phenomenon is the same. In Jiangsu, there was a similar engine emitting black smoke. Due to dirty diesel use, the SCV valve got stuck, causing excessive common rail pressure and resulting in black smoke. Clean the SCV valve to eliminate the fault
3. Use the engine data cable to detect and check for cylinder breakage, correct the engine cylinder compensation value, and eliminate black smoke caused by injector failure
4. Check that the common rail pressure is normal
5. When detecting the EGR opening, it was found that when the indicated opening was 0%, the measured value was 39%. When adjusting the indicated opening, there was no change in the measured value or the deviation from the indicated value was significant

Handling method:

It is inferred that the EGR valve is faulty. Unplug the EGR valve plug, clean the dust and impurities inside the plug. Use a data cable to check and repeatedly adjust the opening of the EGR valve. Suddenly, it was found that the measured value of the EGR valve was close to the indicated value, and the machine engine no longer emitted black smoke. The machine resumed normal use
Speculation: EGR solenoid valve is at high temperature, causing malfunction due to card sticking