A system includes a controller configured to receive a signal acquired by the at least one knock sensor coupled to a reciprocating device, to sample the received signal, to analyze the sampled signal, and to utilize standard quality control (SQC) techniques to perform real-time diagnostics on the reciprocating device based on the analyzed signal.

Methods and systems are provided for adjusting spark and/or fuel injection to a cylinder based on late combustion, partial burn, or misfire in a neighboring cylinder. In one example, a method may include deactivating spark and fuel injection to a second cylinder receiving exhaust residuals from combustion in a first cylinder, the first cylinder experiencing a misfire or late combustion event. Mitigating actions are performed in the second cylinder before the occurrence of a pre-ignition event.

A method of deriving reciprocating device component health includes receiving a signal from a knock sensor coupled to a reciprocating device, deriving total harmonic distortion (THD) at one or more frequencies, and determining whether the derived THD exceeds a threshold value.

Methods and systems are provided for operating a variable displacement engine that includes a knock control system. Engine knock background noise levels determined during all cylinders operating mode may be determined via two filters that are constructed in parallel. Output of the two filters may be the basis for determining the presence or absence of engine knock.

A glow plug including a substantially cylindrical housing extending in an axial direction; a rod-shaped heater unit having a front end protruding from the front end of the housing and movable in the axial direction; a connecting member connecting the heater unit to the housing within the housing and allowing the heater unit to move in the axial direction; and a pressure sensor that detects pressure received by the heater unit. The heater unit has a large-diameter portion at the rear end thereof and a small-diameter portion frontward of the large-diameter portion and having a diameter smaller than the diameter of the large-diameter portion. The connecting member connects the small-diameter portion of the heater unit to the housing within the housing.

A glow plug including a substantially cylindrical housing extending in an axial direction; a rod-shaped heater unit having a front end protruding from the front end of the housing and movable in the axial direction; a connecting member connecting the heater unit to the housing within the housing and allowing the heater unit to move in the axial direction; and a pressure sensor that detects pressure received by the heater unit. The heater unit has a large-diameter portion at the rear end thereof and a small-diameter portion frontward of the large-diameter portion and having a diameter smaller than the diameter of the large-diameter portion. The connecting member connects the small-diameter portion of the heater unit to the housing within the housing.

Method to detect and control detonation phenomena in an internal combustion engine provided with a number of cylinders and with at least two detonation sensors. For each combustion cycle as a function of the cylinder and of the engine point that is being explored, the method comprises the steps of processing the signal coming from each detonation sensor so as to determine a detonation energy for each detonation sensor; calculating a detonation index for each detonation sensor and controlling the internal combustion engine as a function of a total detonation index through the algebraic sum of the detonation indexes for each detonation sensor.

Method to detect and control detonation phenomena in an internal combustion engine provided with a number of cylinders and with at least two detonation sensors. For each combustion cycle as a function of the cylinder and of the engine point that is being explored, the method comprises the steps of processing the signal coming from each detonation sensor so as to determine a detonation energy for each detonation sensor; calculating a detonation index for each detonation sensor and controlling the internal combustion engine as a function of a total detonation index through the algebraic sum of the detonation indexes for each detonation sensor.

In one embodiment, a method is provided. The method includes receiving a plurality of signals representative of an engine noise transmitted via a plurality of noise sensors, wherein the noise sensors are disposed in a grid about an engine. The method further includes receiving a knock sensor signal representative of an engine noise transmitted via a knock sensor. The method additionally includes deriving a combustion event based on the knock sensor signal, and deriving an engine condition based on the plurality of signals and the combustion event. The method also includes communicating the engine condition.

An engine system for a vessel propulsion device includes an engine including an intake amount adjusting unit and an ignition plug, and configured to generate a drive force for the vessel propulsion device. The engine system includes an ignition timing control unit, a knocking detecting unit, a knocking retard control unit that retards the ignition timing of the ignition plug by a unit retard amount when the knocking detecting unit detects knocking, an abnormality judging unit that, when a state where the knocking detecting unit detects knocking at intervals within a predetermined time continues, judges that an abnormality has occurred based on a continued state of knocking detection, and an intake amount limiting unit that limits the intake amount of the engine based on judgment of an abnormality made by the abnormality judging unit.