Methods and systems are provided for adjusting a substitution ratio based on water in a combustion mixture of a multi-fuel engine. In one example, a method includes adjusting a substitution ratio in response to an amount of water provided to a multi-fuel engine configured to combust a first fuel and a second fuel, the second fuel different than the first fuel.

The disclosure relates to a method for controlling compression ignition combustion phasing in an internal combustion engine, the method comprising providing a high heat of vaporization fuel charge, the high heat of vaporization fuel charge having a latent heat of vaporization; and directly injecting a spray of the fuel charge into a cylinder of an internal combustion engine during the intake stroke, the internal combustion engine having a gas exchange stage and a combustion stage, the injecting from a single injector and occurring at least immediately after Top Dead Center during the gas exchange stage.

A method for determining an air mass in an air separator of a water direct injection system for injecting a water/fuel mixture into a combustion chamber of an engine of a motor vehicle. The air separator is disposed between a water pump for delivering water of the water/fuel mixture and a high-pressure pump for feeding the water/fuel mixture to a high-pressure injector for injecting the water/fuel mixture into the combustion chamber. The method includes increasing a pressure of the water from a first pressure value to a second pressure value by the water pump, determining a water volume delivered by the water pump during the increasing of the pressure of the water by the water pump, and determining the air mass in the air separator on a basis of the determined water volume delivered by the water pump.

A method for determining an air mass in an air separator of a water direct injection system for injecting a water/fuel mixture into a combustion chamber of an engine of a motor vehicle. The air separator is disposed between a water pump for delivering water of the water/fuel mixture and a high-pressure pump for feeding the water/fuel mixture to a high-pressure injector for injecting the water/fuel mixture into the combustion chamber. The method includes increasing a pressure of the water from a first pressure value to a second pressure value by the water pump, determining a water volume delivered by the water pump during the increasing of the pressure of the water by the water pump, and determining the air mass in the air separator on a basis of the determined water volume delivered by the water pump.

A split cycle internal combustion engine includes a combustion cylinder accommodating a combustion piston and a compression cylinder accommodating a compression piston. The engine also includes a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to close during the return stroke of the combustion piston, before the combustion piston has reached its top dead centre position (TDC), when the indicated parameter is less than a target value for the parameter; and close on completion of the return stroke of the combustion piston, as the combustion piston reaches its top dead centre position (TDC), when the indicated parameter is equal to or greater than the target value for the parameter.

A split cycle internal combustion engine includes a combustion cylinder accommodating a combustion piston and a compression cylinder accommodating a compression piston. The engine also includes a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to close during the return stroke of the combustion piston, before the combustion piston has reached its top dead centre position (TDC), when the indicated parameter is less than a target value for the parameter; and close on completion of the return stroke of the combustion piston, as the combustion piston reaches its top dead centre position (TDC), when the indicated parameter is equal to or greater than the target value for the parameter.

Spark ignition engine operation at higher RPM so as to reduce alcohol requirements in high efficiency alcohol enhanced gasoline engines is disclosed. Control of engine upspeeding (use of a higher ratio of engine RPM to wheel RPM) so as to achieve an alcohol reduction objective while limiting any decrease in efficiency is described. High RPM alcohol enhanced gasoline engine operation in plug-in series hybrid powertrains for heavy duty trucks and other vehicles is also described.

Spark ignition engine operation at higher RPM so as to reduce alcohol requirements in high efficiency alcohol enhanced gasoline engines is disclosed. Control of engine upspeeding (use of a higher ratio of engine RPM to wheel RPM) so as to achieve an alcohol reduction objective while limiting any decrease in efficiency is described. High RPM alcohol enhanced gasoline engine operation in plug-in series hybrid powertrains for heavy duty trucks and other vehicles is also described.

Methods and systems are provided for adjusting the amount of secondary fluid being injected into an engine. In one example, a method may include adjusting an amount of secondary fluid injected at an engine cylinder based on a secondary fluid injection amount estimated from outputs of an exhaust oxygen sensor. For example, the secondary fluid injection amount may be estimated based on a first change in pumping current of the exhaust oxygen sensor between a first and second reference voltage when only fuel is injected into the engine cylinder and a second change in pumping current of the exhaust oxygen sensor between the first and second reference voltage when fuel and the secondary fluid are injected into the engine cylinder.

Methods and systems are provided for adjusting the amount of secondary fluid being injected into an engine. In one example, a method may include adjusting an amount of secondary fluid injected at an engine cylinder based on a secondary fluid injection amount estimated from outputs of an exhaust oxygen sensor. For example, the secondary fluid injection amount may be estimated based on a first change in pumping current of the exhaust oxygen sensor between a first and second reference voltage when only fuel is injected into the engine cylinder and a second change in pumping current of the exhaust oxygen sensor between the first and second reference voltage when fuel and the secondary fluid are injected into the engine cylinder.