A watercraft propulsion system includes a propulsion unit to be driven by an engine. The engine includes a cylinder block, an air intake channel, an exhaust channel, a supercharging device, and a fuel injector. The watercraft propulsion system includes the engine, the propulsion unit to be driven by the engine, a rotation speed sensor to detect a rotation speed of the engine, an air intake pressure sensor to detect an air intake pressure of the engine, and a controller. The controller is configured or programmed to compute a command fuel injection amount so that the engine performs a combustion operation at an air/fuel ratio in a lean-burn range (lean-combustion range) according to the rotation speed detected by the rotation speed sensor and the air intake pressure detected by the air intake pressure sensor, and to drive the fuel injector based on the computed command fuel injection amount.

A control device estimates a leakage gas amount with respect to gas that leaks to an upstream side from a downstream side of a fresh air introduction valve when the fresh air introduction valve is closed. If the leakage gas amount is equal to or greater than a predetermined value when there is a request to open the fresh air introduction valve, a target opening degree of the fresh air introduction valve is determined based on the engine speed and intake pressure, and also a correction opening degree with respect to the target opening degree is calculated based on the leakage gas amount. The fresh air introduction valve is opened to an opening degree greater than the target opening degree by an amount corresponding to the correction opening degree, to thereby cause leakage gas that is accumulated in a fresh air introduction passage to flow into an intake passage together with a required amount of fresh air.

Systems and methods are described for operating a turbocharger. A current exhaust manifold pressure is determined based on an engine operating condition. A current operating condition of the turbocharger is determined. A surge correction factor is determined based on the current operating condition of the turbocharger. The current exhaust manifold pressure is adjusted based on the surge correction factor.

Systems and methods are described for operating a turbocharger. A current exhaust manifold pressure is determined based on an engine operating condition. A current operating condition of the turbocharger is determined. A surge correction factor is determined based on the current operating condition of the turbocharger. The current exhaust manifold pressure is adjusted based on the surge correction factor.

An example engine system is disclosed. The engine system may control a turbocharger of an internal combustion engine, and more particularly control a boost pressure provided by a turbocharger to an internal combustion engine. An example method for controlling a boost pressure provided by a turbocharger may include receiving a boost pressure demand and identifying a compressor speed demand to achieve the received boost pressure demand. The method may also include converting the compressor speed demand into a kinetic energy demand of the turbocharger rotating components and controlling the kinetic energy of the turbocharger rotating components to meet the kinetic energy demand by controlling power supplied by the turbine and the electric motor assist.

An example engine system is disclosed. The engine system may control a turbocharger of an internal combustion engine, and more particularly control a boost pressure provided by a turbocharger to an internal combustion engine. An example method for controlling a boost pressure provided by a turbocharger may include receiving a boost pressure demand and identifying a compressor speed demand to achieve the received boost pressure demand. The method may also include converting the compressor speed demand into a kinetic energy demand of the turbocharger rotating components and controlling the kinetic energy of the turbocharger rotating components to meet the kinetic energy demand by controlling power supplied by the turbine and the electric motor assist.

Methods and systems for adjusting a branch communication and wastegate valve in a dual scroll turbocharger system are provided. In one example, a method may include adjusting the branch communication and wastegate valve in a passage connecting a first scroll, a second scroll, and a wastegate passage may control an amount of exhaust flow to a turbine during certain engine operating conditions.

An auxiliary-machine control device equipped with: a command-value acquisition unit for acquiring an operation command value for a device to be controlled and an allowable range for the operation amount of control means for controlling the operating state of the device to be controlled; an operation-amount calculation unit for calculating the operation amount for the control means on the basis of the acquired operation command value; and an operation-amount determination unit for outputting the calculated operation-amount signal to the device to be controlled if the operation amount calculated by the operation-amount calculation unit falls within the allowable range, and outputting an upper-limit value or a lower-limit value for the operation-amount allowable range if the calculated operation amount falls outside of the allowable range.

Devices and methods are described for remotely tuning a diesel engine of a vehicle using a pneumatic control device. A tunable control system for an aneroid fuel control (AFC) injection system includes a pneumatic control device that has a pneumatic pressure regulator configured to be adjusted by a first tuning adjustment controller and a pneumatic flow control valve configured to be adjusted by a second tuning adjustment controller. An air signal line links the pressure regulator to the flow control valve. The control system also includes an inlet line connected to the control device and configured to be connected to an air pressure source of an engine. An outlet line is connected to the control device and is configured to be connected to an AFC of an engine.

According to a device and a method for controlling an internal combustion engine, a control device (38) enables controllability of the internal combustion engine to be improved by preventing surging from occurring upon starting or stopping of the internal combustion engine, by opening a relief valve (28) as a turbine rotational speed reaches a surging rotational speed when the control device (38) causes a motor generator (32) to assist in rotation of the turbocharger (12) upon starting of a diesel engine body (11).