Abstract: Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a low-pressure pump operable to pump fuel from a fuel source at a first pressure, a high-pressure pump operable to increase the first pressure to a second pressure, a valve positioned between the low-pressure pump and the high-pressure pump and operable to control fuel flow to the high-pressure pump, a common fuel rail fluidly coupling the high-pressure pump to a plurality of fuel injectors coupled to cylinders of an engine, and a controller. The controller is operable to adjust an amount of valve electrical current supplied to the valve to reach a commanded pressure of the common fuel rail during cylinder firing conditions, the supplied valve electrical current adjusted based on a valve pre-firing correction factor for the valve obtained based on valve electrical current prior to cylinder firing commencing.

Abstract: Various methods and systems are provided for diagnosing an engine component based on a measured engine speed during an engine shutdown event. As one embodiment, a method for an engine includes measuring an engine speed drop rate, via an engine speed sensor, during an engine shutdown event; and indicating a change in performance of one of the engine speed sensor or an additional engine component in response to the measured engine speed drop rate deviating from a reference engine speed drop rate by a pre-set or pre-defined threshold rate.

Abstract: Various methods and systems are provided for an exhaust gas cooler. In one example, a method includes controlling a flow of coolant to at least a first stage of a plurality of stages of an exhaust gas cooler relative to a second stage of the plurality of stages to maintain at least one of: a controlled amount of heat removal from the first stage relative to the second stage, an about equal coolant temperature increase across the first stage relative to the second stage; an about equal gas temperature decrease across the first stage relative to the second stage; and an about equal gas heat removal across the first stage relative to the second stage.

Abstract: A system includes an impedance gas sensor configured to be in contact with one or more hydrocarbons. The impedance sensor includes electrodes and a sensing region circuit that is configured to have a sensing material and to generate electrical stimuli to the sensing material upon exposure to one or more hydrocarbons at one or more of a reduced heater voltage or a reduced sensing region temperature as compared to a prescribed heater voltage or a prescribed sensing region temperature. The system also includes one or more processors configured to receive electrical signals from the sensor, where the electrical signals are representative of impedance responses of the sensing material to one or more hydrocarbons. The one or more processors also are configured to analyze the impedance responses and determine an amount of at least one hydrocarbon of interest in the one or more hydrocarbons.

Abstract: A system includes an impedance gas sensor configured to be in contact with one or more hydrocarbons. The impedance sensor includes electrodes and a sensing region circuit that is configured to have a sensing material and to generate electrical stimuli to the sensing material upon exposure to one or more hydrocarbons at one or more of a reduced heater voltage or a reduced sensing region temperature as compared to a prescribed heater voltage or a prescribed sensing region temperature. The system also includes one or more processors configured to receive electrical signals from the sensor, where the electrical signals are representative of impedance responses of the sensing material to one or more hydrocarbons. The one or more processors also are configured to analyze the impedance responses and determine an amount of at least one hydrocarbon of interest in the one or more hydrocarbons.

Abstract: Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a high-pressure fuel pump operable to increase fuel pressure from a first pressure to a second pressure, a common fuel rail fluidly coupling the high-pressure fuel pump to a plurality of fuel injectors each of which is operable to inject fuel to individual cylinders of an engine, a pressure sensor operable to detect a pressure of fuel at the common fuel rail, and a controller operable to diagnose a condition of the high-pressure fuel pump based on output from the pressure sensor.

Abstract: A system includes a sensor configured to be in contact with lubricant within an engine of a vehicle system. The sensor includes a sensing region circuit that is configured to generate stimuli at different times during an operational life of the engine. The system also includes one or more processors configured to receive signals from the sensor. The signals are representative of responses of the lubricant to the stimuli. The one or more processors are configured to analyze the responses and determine a characteristic of the lubricant that represents one or more of a total base number (TBN) or a total acid number (TAN) of the lubricant. The one or more processors are configured to determine an unhealthy state of one or more of the engine or the lubricant based on the characteristic of the lubricant that is determined.

Abstract: Various methods and systems are provided for diagnosing an engine component based on a measured engine speed during an engine shutdown event. As one embodiment, a method for an engine includes measuring an engine speed drop rate, via an engine speed sensor, during an engine shutdown event; and indicating a change in performance of one of the engine speed sensor or an additional engine component in response to the measured engine speed drop rate deviating from a reference engine speed drop rate by a pre-set or pre-defined threshold rate.

Abstract: Various methods and systems are provided for diagnosing a condition of a fuel injector of an engine. In one example, a method for an engine includes injecting a first pulse of fuel as a first pilot injection into a first subset of cylinders of a plurality of engine cylinders, where the first pilot injection precedes a primary injection of fuel into the first subset of cylinders by a duration; correlating a first response in an engine operating parameter to the first pilot injection; and adjusting the primary injection of fuel into the first subset of cylinders based on the first response. In one example, the first pilot injection precedes the primary injection by a predefined short duration and the primary injection of fuel is adjusted within a predefined or preset upper limit and lower limit.

Abstract: Various methods and systems are provided for health assessments of a fuel system. In one example, a fuel system includes a low-pressure pump operable to pump fuel from a fuel source at a first pressure, a high-pressure pump operable to increase the first pressure to a second pressure, a valve positioned between the low-pressure pump and the high-pressure pump and operable to control fuel flow to the high-pressure pump, a common fuel rail fluidly coupling the high-pressure pump to a plurality of fuel injectors coupled to cylinders of an engine, and a controller. The controller is operable to adjust an amount of valve electrical current supplied to the valve to reach a commanded pressure of the common fuel rail during cylinder firing conditions, the supplied valve electrical current adjusted based on a valve pre-firing correction factor for the valve obtained based on valve electrical current prior to cylinder firing commencing.

Abstract: A fuel injector assembly in one embodiment includes a nozzle, at least one needle, and at least one actuator. The nozzle includes at least one cavity in fluid communication with nozzle openings. The at least one needle is movably disposed within the at least one cavity, and prevents flow through the nozzle openings in a closed position. The at least one actuator is configured to move the at least one needle within the cavity. The at least one actuator is configured to move the at least one needle to at least a first fuel delivery configuration and a second fuel delivery configuration. A first amount of fuel is delivered through the nozzle openings with the at least one needle in the first fuel delivery configuration, and a second amount of fuel is delivered through the nozzle openings with the at least one needle in the second fuel delivery configuration.

Abstract: Various methods and systems are provided for individually adjusting fueling to cylinders of an engine based on an output of a knock sensor coupled to each cylinder. In one embodiment, a method for a multi fuel engine comprises individually adjusting, for each cylinder of the engine, one or more of a gas flow rate of gaseous fuel, a diesel flow rate of diesel fuel, an injection or induction timing of gaseous fuel, or an injection timing of diesel fuel based on each of an output of an individual knock sensor for each cylinder, a knock threshold for current engine operating conditions, and a reference value of individual cylinder output.

Abstract: A sensing system includes a sensor and one or more processors. The sensor includes a sensing region in contact with an industrial fluid. The sensing region includes electrodes and a sensing region circuit electrically connected to the electrodes. The sensing region circuit generates an electrical stimulus having multiple different frequencies that are applied to the industrial fluid via the electrodes. The one or more processors receive one or more electrical signals from the sensor representative of an impedance response of the sensing region to the electrical stimulus. The one or more processors analyze the impedance response and determine at least one of a contaminant concentration of an external contaminant in the industrial fluid, an acid concentration of acidic components in the industrial fluid, or a base concentration of basic components in the industrial fluid based on the impedance response.

Abstract: Various methods and systems are provided for individually adjusting fueling to cylinders of an engine based on an output of a knock sensor coupled to each cylinder. In one embodiment, a method for a multi fuel engine comprises individually adjusting, for each cylinder of the engine, one or more of a gas flow rate of gaseous fuel, a diesel flow rate of diesel fuel, an injection or induction timing of gaseous fuel, or an injection timing of diesel fuel based on each of an output of an individual knock sensor for each cylinder, a knock threshold for current engine operating conditions, and a reference value of individual cylinder output.

Abstract: Various methods and systems are provided for a pressure relief valve of a fuel system. In one example, a valve includes a first chamber in fluid communication with a first fuel line, a second chamber in fluid communication with a second fuel line and in fluid communication with a fuel storage tank, a piston separating the first chamber from the second chamber, and a needle coupled to the piston and controlling a flow passage between the second fuel line and the second chamber, where the piston and needle are sized such that a force applied on the piston by the first chamber parallel to an axis of movement of the piston maintains the needle in a closed position when the first fuel line flows fuel at a first pressure and the second fuel line flows fuel at a second pressure, the second pressure greater than the first pressure.