A controller, in electrical communication with the one or more of the injectors and a high-pressure fuel pump, generates a first signal responsive to which the valve in the injector opens or closes and a second signal responsive to which the high-pressure fuel pump increases or decreases the pressure level in the fuel accumulator. The system may also include one or more sensors to detect a pressure within the air manifold and to detect the pressure within the fuel accumulator. The controller is programmed to calculate an in-cylinder gas pressure. When the engine is operating at a maximum engine load and the in-cylinder gas pressure reaches or exceeds a maximum pressure limit, the controller transmits one or more signals to adjust the fuel injection timing and/or adjust the pressure in the fuel accumulator to maintain NOx and fuel consumption within acceptable limits.