1997 Kobelco SK220LC Mark IV Serial number LLU2328 5.9 Cummins engine Engine is loading up when you make a small movement with the joystick. This happens as soon as you touch the controls. Engine immediately goes into full load. If you operate in H mode (I believe high pressure) at wide open throttle, the machine will power through it, but it is under full load (as if someone was trying to operate an attachment with no attachment connected). Stating this to show that I believe it is not an engine issue. Engine has tons of power. This problem does not occur in the following functions: swing left or right, Left Track, and stick in. These operate 100% normally in all power modes. It does occur in boom up, boom down, right track, and bucket curl and dump. If you push the joystick all the way in these functions, it will unload the engine, and operates normally. If the joystick is slightly moved, or moved moderately, machine instantly goes into full load. If the machine is at half throttle, and you touch the boom or bucket lever, it will stall the engine. I have removed the pump control valve (or regulator) on the pump closest to the engine. Inspected it, replaced all Orings. Everything seemed perfect inside, and it made no change to the problem. Any help would be greatly appreciated.
All those functions are on the P1 pump which is the closest to the engine. The regulators can be swapped from P2 to P1 and see if the issue changes to the left joystick.