A prescribed air-fuel ratio feedback control region for performing feedback-control of air-fuel ratio has therein: a first region where fuel is injected, during one combustion cycle, only from a first fuel injection valve injecting fuel directly into a cylinder; and a second region where fuel is injected, during one combustion cycle, from both of the first fuel injection valve and a second fuel injection valve injecting fuel into an air-intake passage. A second region is configured such that an amount of fuel injected from the first fuel injection valve and an amount of fuel injected from the second fuel injection valve remain at a given constant ratio regardless of operating status. A diagnosis on the first and second fuel injection valves is performed by using a first air-fuel ratio learning value learned in the first region and a second air-fuel ratio learning value learned in the second region.

A system includes a controller having a control signal generation unit that provides control signals to actuate one or more valve actuators of an engine to a desired position, and control signals to modify one or more operational parameters and an operational mode of the engine. A parameter signal process unit receives parameter signals corresponding to at least one operational parameter of the engine, and at least one sensor coupled to the engine. At least one sensor corresponds to a position of a valve. A failure detection unit generates at least one fault code corresponding to one or more failure modes. A failure mode isolation unit isolates a failure mode from the one or more failure modes in response to modifying the operational parameters or the operational mode, causing actuation of the valves to a desired position, or receiving the parameter signals and the sensor.

Methods and systems are provided for diagnosing the functioning of a variable displacement oil pump. In one example, a method may include commanding a change in displacement of the variable displacement oil pump during a vehicle keyed-off condition and diagnosing a degradation of the oil pump based on a corresponding change in an estimated crankcase pressure.

A locomotive engine control system includes one or more processors operably connected to fuel supply devices. The fuel supply devices are configured to supply fuel into different corresponding cylinders of an engine. The one or more processors are configured to monitor a fuel quantity injected into the cylinders of the engine before and after communication of an overfuel control signal. The overfuel control signal commands the fuel supply device corresponding to a first cylinder of the cylinders to supply excess fuel into the first cylinder. Responsive to the fuel quantity that is monitored not decreasing after the communication of the overfuel control signal, the one or more processors are configured to determine that the fuel supply device corresponding to the first cylinder is defective, and may generate one or more control signals indicative of the fuel supply device corresponding to the first cylinder being defective.

Methods and systems are provided for a vehicle engine having a pre-chamber ignition system. In one example, a method may include adjusting one or more of an air injection amount and a fuel injection amount to a pre-chamber of an engine based on an air injection offset and a fuel injection offset learned while discontinuing fueling to cylinders of the engine and reducing air flow through the engine. In this way, air and fuel may be more accurately provided to the pre-chamber, thereby decreasing an occurrence of pre-chamber misfire.

Methods and systems are provided for diagnosing an active exhaust valve in an exhaust system based on thermal data. In one example, a method may include indicating degradation of a first active exhaust valve positioned in a first exhaust pipe of a first engine bank based on a difference between a first temperature of exhaust downstream of the first active exhaust valve and a second temperature of exhaust downstream of a second active exhaust valve positioned in a second exhaust pipe of a second engine bank. Degradation of the valve may be confirmed based on thermal image data acquired at outlets of the first and second exhaust pipes.

An apparatus for diagnosing an exhaust gas recirculation (EGR) valve includes: an EGR apparatus including an EGR line connecting an exhaust line and an intake line and an EGR valve installed in the EGR line; an electric supercharger installed in the intake line to change an internal pressure of an intake manifold; a manifold pressure sensor measuring the internal pressure of the intake manifold; and a controller that when an engine is stopped while a vehicle is running, learns on an amount of opening of the EGR valve, diagnoses a fixation of the EGR valve and e a leakage of the EGR valve based on the internal pressure of the intake manifold detected by the manifold pressure sensor.

Systems and methods are provided for determining and correcting air/fuel imbalance between cylinders of an internal combustion engine. A deactivation strategy is determined and implemented. An evaluation is made of whether the engine is operating with an air/fuel imbalance between cylinders. When an imbalance is identified, an alternate deactivation strategy is implemented. Based on outcomes of the alternate deactivation strategy, a source cylinder of the air/fuel imbalance is identified, and fuel flow to the source cylinder is corrected.

Methods and systems are provided for an engine. A condition of the engine may be diagnosed based on information provided by signals from a generator operationally connected to the engine and/or other signals associated with the engine. Different types of degradation may be distinguished based on discerning characteristics within the information. Thus, a degraded engine component may be identified in a manner that reduces service induced delay.

The invention relates to a maintenance system for a fuel injection system provided in an internal combustion engine, the fuel injection system defining a hydraulic circuit having a high-pressure pump, a solenoid valve, a pressure sensor, a metering solenoid valve, a common rail and injectors. The maintenance system includes a manual control unit connected to a hydraulic unit, the hydraulic unit being capable of being inserted into the hydraulic circuit of the fuel injection system and including a test solenoid valve and a test pressure sensor mounted in a body provided with an inlet mouth, an outlet mouth and a leakage mouth.