My komatsu PC130-7 suffers from a combination problem, which if arm and boom is raised at the same time, one of them will slow down or stop completely until the another one is raised fully, pressure in pump is normal, engine rpm is normal meanwhile if i disconnect the the pump solenoid the engine doesn't drop. Reducing is ok. Any suggestion? Thank you.
May be a hydraulic volume issue not pressure .How many hours on filiters
Which one slows or stops? Its very likely a pressure compensator on the control valve. Each port has one, looks like a 30mm plug. Pull out the 4 for the two circuits you're describing. DONT MIX THEM UP as the surface areas are different for all of them and could cause issues if swapped. Things to look for are major scoring or mushrooming. As well there are two black teflon seals on each and they tend to wash away over time. The good news is that the seals are not sold separately and the valves are $700-$1000 each. Have fun.