Methods and systems are provided for diagnosing a positive crankcase ventilation (PCV) system. In one example, a PCV system diagnostic method is provided that includes a determining a fault condition in a positive crankcase ventilation (PCV) system by comparing a pressure sampled from a pressure sensor positioned on a clean side of an oil separator coupled to a crankcase with a modeled pressure representing an expected pressure on the clean side of the oil separator.

A blow-by gas treatment device includes a first blow-by gas pipe, a second blow-by gas pipe, a first pipe joint located on a first head cover, the first blow-by gas pipe being connected to the first pipe joint, a second pipe joint located on a second head cover, the second blow-by gas pipe being connected to the second pipe joint, a first union located on the first pipe joint, a second union located on the second pipe joint, and a pressure sensor connected to the first pipe joint by the first union and connected to the second pipe joint by the second union.

Methods and systems are provided for diagnosing a positive crankcase ventilation (PCV) system. In one example, a PCV system diagnostic method is provided that includes a determining a fault condition in a positive crankcase ventilation (PCV) system by comparing a pressure sampled from a pressure sensor positioned on a clean side of an oil separator coupled to a crankcase with a modeled pressure representing an expected pressure on the clean side of the oil separator.

An anomaly diagnostic device for an onboard internal combustion engine includes a parameter deriving unit and a leaking anomaly diagnostic unit. The parameter deriving unit is configured to derive a determination parameter such that, when a PCV pressure sensor value that indicates a pressure detected by a PCV pressure sensor is less than an atmospheric pressure, a value of the determination parameter increases as the difference between the PCV pressure sensor value and the atmospheric pressure increases. The leaking anomaly diagnostic unit is configured to perform a leaking anomaly diagnostic process that diagnoses that there is an anomaly at a portion of a blow-by gas passage that is closer to an intake passage than to a connection portion of the PCV pressure sensor when the determination parameter derived when an intake air amount changes is less than a threshold.

A process of evaluating performance of a positive crankcase ventilation (PCV) valve is disclosed. The process includes utilizing an optical sensor coupled to the PCV valve to collect baseline valve position data during a calibration phase. The baseline valve position data represents satisfactory PCV valve performance. The process also includes utilizing the optical sensor to collect operational valve position data during an operational phase. The process further includes determining whether a deviation of the operational valve position data from the baseline valve position data satisfies a performance threshold associated with unsatisfactory PCV valve performance. When the deviation satisfies the performance threshold, the process includes communicating an error code to an alert indicator.

A method for operating an internal combustion engine wherein the internal combustion engine to be operated is supplied with lubricating oil via an oil circuit. A measurement value of a total base number and/or a measurement value of the viscosity of the lubricating oil currently used in the oil circuit for the lubrication is detected. Dependent on the established measurement value of the total base number and/or dependent on the established measurement value of the viscosity an exchange oil quantity for the oil circuit is determined. Currently used lubricating oil to an extent corresponding to the exchange oil quantity is removed from the oil circuit. New lubricating oil to an extent corresponding to the exchange oil quantity is supplied to the oil circuit.

A method for operating an internal combustion engine that is supplied with lubricating oil via an oil circuit. A measurement value of the total base number and/or a measurement value of the oxidation of lubricating oil currently used in the oil circuit for the lubrication is detected. Dependent on the established measurement value of the total base number and/or dependent on the established measurement value of the oxidation an exchange oil quantity for the oil circuit is determined. Currently used lubricating oil to an extent corresponding to the exchange oil quantity is removed from the oil circuit and new lubricating oil to an extent corresponding to the exchange oil quantity is supplied to the oil circuit.

An on-vehicle oil sensor includes an enclosure and a detecting unit. The enclosure includes: an enclosure inner space provided inside the enclosure and configured to allow oil to enter the enclosure inner space; and a plurality of oil paths provided in the enclosure and connecting an exterior of the enclosure to the enclosure inner space. The detecting unit is configured to detect at least one of pressure of oil in the enclosure inner space and temperature of oil in the enclosure inner space.

An internal combustion engine includes on-off valves that configure a closed space by closing an internal space of a breather line, a pump that depressurizes or pressurizes the closed space, a pressure sensor that detects a pressure of the closed space, and an abnormality assessment element that assesses abnormality of the breather line. The abnormality assessment element assesses abnormality of the breather line based on a pressure change of the closed space in a case where the closed space is depressurized or pressurized by the pump.

An oil state detection device includes an index member, a lighting device that illuminates the index member, and a photographing device that photographs the index member through oil in a machine device.