Abstract: Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Abstract: Various methods and systems are provided for a multi-fuel capable engine. The system includes a liquid fuel system to deliver liquid fuel to an engine, a gaseous fuel system to deliver gaseous fuel to the engine, and a control system. The control system can control and test the liquid and gaseous fuel systems.

Abstract: Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Abstract: Various methods and systems are provided for a multi-fuel capable engine. The system includes a liquid fuel system to deliver liquid fuel to an engine, a gaseous fuel system to deliver gaseous fuel to the engine, and a control system. The control system can control and test the liquid and gaseous fuel systems.

Abstract: Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Abstract: Methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system may include first and second fuel systems to deliver liquid and gaseous fuels, respectively, to at least one cylinder of the engine, and a controller. The controller may be configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder to compression ignite the liquid fuel and combust the gaseous fuel in the at least one cylinder, and retard an injection timing of the injection of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel. In some examples, the controller may further be configured to adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on the measured parameter.

Abstract: Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel.

Abstract: Various methods and systems are provided for a multi-fuel capable engine. The system includes a liquid fuel system to deliver liquid fuel to an engine, a gaseous fuel system to deliver gaseous fuel to the engine, and a control system. The control system can control and test the liquid and gaseous fuel systems.

Abstract: Various methods and systems are provided for adjusting fueling to groups of cylinders of an engine based on individual cylinder knock sensor outputs. As one example, a system for an engine includes: a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the engine cause the controller to: deliver natural gas and diesel fuel to a first group of cylinders at amounts that produce a common, first substitution ratio of natural gas; deliver natural gas and diesel fuel to a second group of cylinders at amounts that produce a common, second substitution ratio of natural gas; and change a makeup of each of the first group of cylinders and the second group of cylinders based on individual knock sensor outputs of each cylinder of the first group of cylinders and the second group of cylinders.

Abstract: Various methods and systems are provided for adjusting fueling to groups of cylinders of an engine based on individual cylinder knock sensor outputs. As one example, a system for an engine includes: a controller with computer readable instructions stored on non-transitory memory that when executed during operation of the engine cause the controller to: deliver natural gas and diesel fuel to a first group of cylinders at amounts that produce a common, first substitution ratio of natural gas; deliver natural gas and diesel fuel to a second group of cylinders at amounts that produce a common, second substitution ratio of natural gas; and change a makeup of each of the first group of cylinders and the second group of cylinders based on individual knock sensor outputs of each cylinder of the first group of cylinders and the second group of cylinders.

Abstract: Various methods and systems are provided for adjusting an amount of intake airflow diverted away from an intake manifold and to atmosphere in response to a temperature of exhaust entering a turbocharger turbine and a target pre-turbine temperature. In one example, an amount of intake airflow entering engine cylinders, and thus an air-fuel ratio entering the engine cylinders, may be controlled to maintain the temperature of exhaust entering the turbocharger turbine at the target pre-turbine temperature.

Abstract: Various systems are provided for delivering fuel to an engine. In one example, a system includes a controller and a fluid system configured to maintain a fluid at a pressure downstream of a check valve. The controller may be configured to determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system, and responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases.

Abstract: Various systems are provided for delivering fuel to an engine. In one example, a system includes a controller and a fluid system configured to maintain a fluid at a pressure downstream of a check valve. The controller may be configured to determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system, and responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases.

Abstract: Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel.

Abstract: Various methods and systems are provided for adjusting an amount of intake airflow diverted away from an intake manifold and to atmosphere in response to a temperature of exhaust entering a turbocharger turbine and a target pre-turbine temperature. In one example, an amount of intake airflow entering engine cylinders, and thus an air-fuel ratio entering the engine cylinders, may be controlled to maintain the temperature of exhaust entering the turbocharger turbine at the target pre-turbine temperature.

Abstract: Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel.

Abstract: Various systems are provided for delivering fuel to an engine. In one example, a system includes a controller and a fluid system configured to maintain a fluid at a pressure downstream of a check valve. The controller may be configured to determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system, and responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases.

Abstract: Various methods and systems are provided for maintaining combustion stability in a multi-fuel engine. In one example, a system comprises a first fuel system to deliver liquid fuel to at least one cylinder of an engine, a second fuel system to deliver gaseous fuel to the at least one cylinder, and a controller. The controller is configured to supply the gaseous fuel to the at least one cylinder, inject the liquid fuel to the at least one cylinder thereby to ignite the liquid fuel and the gaseous fuel in the at least one cylinder via compression-ignition, and adjust an amount of the gaseous fuel relative to an amount of the liquid fuel based on a measured parameter associated with auto-ignition of end gases subsequent to the compression-ignition of the liquid fuel.

Abstract: A method for signaling a driver of a motor vehicle that the motor vehicle is operating in a stoichiometric air/fuel mode or a non-stoichiometric air/fuel mode. The method includes providing an air/fuel sensor, the air/fuel sensor providing a signal that is representative of a stoichiometric air/fuel ratio mixture or a non-stoichiometric air/fuel ratio mixture being supplied to or burned by the motor vehicle. The method also includes providing a powertrain control module that is operable to receive the signal from the air/fuel sensor and to energize a light source when a non-stoichiometric air/fuel ratio mixture signal is received.

Abstract: A method for signaling a driver of a motor vehicle that the motor vehicle is operating in a stoichiometric air/fuel mode or a non-stoichiometric air/fuel mode is disclosed herein. The method includes providing an air/fuel sensor, the air/fuel sensor providing a signal that is representative of a stoichiometric air/fuel ratio mixture or a non-stoichiometric air/fuel ratio mixture being supplied to or burned by the motor vehicle. The method also includes providing a powertrain control module that is operable to receive the signal from the air/fuel sensor and to energize a light source when a non-stoichiometric air/fuel ratio mixture signal is received. In some instances, the non-stoichiometric air/fuel ratio mixture is a fuel enriched air/fuel ratio mixture.