Engine operation and power
Engine stalls under load
When RPM falls and the engine stalls during digging, lifting, travel or other heavy work, distinguish two causes: insufficient engine power, or hydraulics/transmission demanding more load than they should.
Response to hydraulic unlocking
Without operating functions, observe the engine when the hydraulic lock lever is moved to its working position.
Load appears immediately
If RPM falls before touching the joysticks, look for a common hydraulic cause: pump not unloading, excessive displacement commanded by the regulator, a sticking common valve, incorrect LS/PC/EPC signal, failed pump power limiting or a constant command/binding in the control valve. Do not start with the bucket cylinder; load appeared before a function was selected.
It runs normally after unlocking
Compare bucket, arm, boom, swing, travel and auxiliary circuits individually under brief load/at their stop. Which pulls RPM down most? A modest full-load drop is normal; nearly stopping is not. Do not hold a function against its stop for long: it heats the oil quickly.
Only one function lugs the engine
Check that control-valve section, local valve, spool, cylinder/motor, lines and pilot/electrical control.
All functions lug it equally
Hydraulics: pressure, pump regulator, main relief valve, power shift/torque control, LS signal and pilot pressure. Engine: fuel filters, low-pressure supply, loaded Common Rail, injectors, turbo, air filter, boost leaks, DPF/exhaust, EGR, derate and temperature.
Observe parameters under load
The fault may not appear at idle. Watch desired/actual RPM, fuel pressure, actual/desired Common Rail, boost, hydraulic pressure, pump command/position and active power limits.
Air, turbo and exhaust
A loaded engine needs much more air. Check filter, turbo, hoses, intercooler, boost leaks, boost sensors, EGR and exhaust backpressure. Black smoke with power loss particularly supports investigating this direction.
What to observe
Immediate lugging on unlocking or only one function? Which function? Only at the stop or mid-movement? Black smoke, stalling while travelling, unloaded operation, derate and faults.
Related problems
Further service support
Have a fault code?
Problem still there?
If these checks have not identified the cause or the fault returns, contact TSV Servis. The more initial information you provide, the sooner we can identify the next diagnostic direction.
What to send us
Model, S/N, engine, hours, affected function, lock-lever response, RPM and available loaded fuel/hydraulic readings.
Include the make and model, S/N or a nameplate photo, engine model if known, operating hours, exact code or display photo and when the fault occurs.
Also tell us what you have already checked or replaced and the results. Include a photo or short video of the symptom where useful.
+420 722 307 850 · tsvcz@seznam.cz