Engine operation and power
Why will the engine not rev up?
First distinguish whether the controller refuses higher speed or the ECM requests it but the engine cannot deliver. The first points to control, sensors, modes and derate; the second to fuel, air, turbo, exhaust, mechanics or excessive machine load.
Requested versus actual RPM
Observe both values, throttle pedal/dial position, working mode and power limiting. If full operator demand still produces low ECM-requested RPM, consider the pedal/dial sensor, speed potentiometer, wiring, selected mode, emergency limiting, derate from another fault or a command from another machine controller.
High requested RPM, low actual RPM
The engine receives the command but cannot follow it. Split checks into the following three groups.
Fuel
Filters, tank supply, lift pump, low-side pressure, air ingress, actual/desired Common Rail, high-pressure pump, injectors and fuel quality. Observe pressure while the engine tries to accelerate.
Air and boost
Air filter, intake, turbo, boost hoses, intercooler, clamps, leaks downstream of the turbo, actual boost and EGR.
Exhaust
DPF, DOC/SCR, silencer, exhaust flaps and backpressure. Severe restriction can prevent acceleration despite a sound fuel system.
Observe smoke
Its color and presence help direct the next checks.
Black smoke without increasing RPM
Fuel enters but air may be insufficient or exhaust cannot escape freely. First check filter, turbo, boost leaks, EGR and DPF/exhaust. Faulty injectors or incorrect fuel delivery remain possible.
Almost no smoke
Focus more on fuel quantity, system pressure, delivery permission and electronic power limiting.
Is hydraulics loading the engine?
If it revs freely without hydraulics but not after unlocking or operating a function, check pump unloading, displacement control, main valve, LS/PC/EPC, power shift and the relevant circuit. If RPM cannot rise with the machine fully unloaded, the engine or its control is more likely.
Active derate
The ECM may deliberately limit RPM, fuel quantity and power even when engine mechanics are sound. Causes may include DPF, AdBlue/SCR, overheating, oil pressure, fuel system, sensors or engine/machine faults. Check active limiting status, not just the fault code.
If fuel, air and control are sound
Next check compression, valve gear, valve timing, turbo damage, mechanical resistance and cylinder/piston/ring condition.
What to observe
Requested/actual RPM, hydraulics enabled versus disabled, black smoke, power-limiting messages, cold/hot difference and pedal, fuel, boost, DPF or SCR 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
Machine/engine model, S/N, hours, requested/actual RPM, faults, derate, smoke color, fuel pressure, boost and whether hydraulic engagement affects the fault.
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