According to the invention, a diagnostic system is provided for diagnosing a misfire condition is provided of individual engine cylinders in a turbocharged diesel engine having at least a first and a second cylinder associated with a common exhaust path. The system comprises a pressure sensor in an exhaust path, for measuring a pressure value; a crankshaft position sensor, for detecting a rotational crankshaft position; and a processor unit for reading the pressure sensor and the crankshaft position sensor. The processor unit is arranged for performing acts of: sampling pressure values of the pressure sensor in the common exhaust path as a function of crankshaft angle position; attributing for each cylinder fired in succession at least two sampling values (P.sub.α, P.sub.β) for at least two successive crankshaft angle positions of a pressure pulse during a cylinder firing operation; determining a boundary for a coordinate (P.sub.α, P.sub.β) formed by a tuple of sampling values (P.sub.α, P.sub.β); diagnosing a misfire condition if the coordinate formed by said tuple of sampling values is outside the boundary.

A method is provided for ascertaining a torque curve of a hybrid powertrain including a first sub-powertrain an internal combustion engine, and a second sub-powertrain, which is separated from the first sub-powertrain by a torsional elasticity and has an electric machine with a rotor (10). A rotational characteristic value of the first sub-powertrain is detected via a sensor arranged on the torsional elasticity. A rotational characteristic value of the rotor is detected via a device engaged with the rotor. An irregularity in operation of the internal combustion engine is determined based on at least one of the rotational characteristic value of the first sub-powertrain or the rotational characteristic value of the rotor. The electric machine is controlled based on the irregularity m operation.

According to one or more embodiments presently described, a method of operating an internal combustion engine that includes injecting fuel into a combustion chamber to form an air-fuel mixture, where the combustion chamber includes a cylinder head, cylinder sidewalls, and a piston that reciprocates within the cylinder sidewalls. The method may also include detecting pre-ignition of the air-fuel mixture during a detected intake or compression stroke of the piston, determining that a super knock condition could occur, and mitigating formation of a super knock condition by deploying a super knock countermeasure within the detected compression stroke.

A diagnostic system and method that (a) that uses models indicative of both successful firing and skips to determine if cylinders of a skip fire controlled internal combustion engine have successfully fired or successfully skipped and (b) uses filtered exhaust gas pressure readings for detecting faults associated with EGR systems and/or turbocharger systems.

A CPU determines that misfires are occurring in a cylinder subject to determination of whether misfires are occurring when a value obtained by subtracting a rotation fluctuation amount ΔT30[n−2] from a rotation fluctuation amount ΔT30[n] is greater than or equal to a determination threshold. The rotation fluctuation amount ΔT30[n] is subject to the misfire determination. The rotation fluctuation amount ΔT30[n−2] is 360° CA earlier than the rotation fluctuation amount ΔT30[n]. When stopping fuel supply to a cylinder #1 and determining whether misfires are occurring in cylinder #4, the CPU determines whether misfires are occurring after executing a correcting process that corrects the determination threshold to a second determination threshold Δth2, which is less than a first determination threshold Δth1.

A piston engine is provided; the piston engine has a cylinder, a main piston and an auxiliary piston; a combustion chamber is formed between the main piston and the auxiliary piston within the cylinder; the main piston has an crankpin offset L0, the auxiliary piston and the main piston move in different frequencies, an extended constant V≈Vc of the combustion chamber is formed from θ to >10° CA; when at a=θ=arc sin[L0/(L+R)] the main piston is at its top dead center; at a=arc sin(L0/R) the side force on the main piston is 0; when peak pressure of combustion is located at PPmax by choosing ignition timing, the most effective torque can be obtained; the torque is controlled by the amount of fuel injected; engine knocking can be prevented by retarded ignition at a>θ.

Methods and systems to determine a presence or absence of engine misfire or spark plug fouling are presented. In one example, rates of change in engine speed are arranged in engine data blocks and root mean square values for the rates of change in engine speed are determined. The presence or absence of engine misfire or spark plug fouling may be based at least in part on the root mean square values.

A classifier capable of predicting if cylinder valves of an engine commanded to activate or deactivate failed to activate or deactivate respectively. In various embodiments, the classifier can be binary or multi-class Logistic Regression, or a Multi-Layer Perceptron (MLP) classifier. The variable displacement engine can operate in cooperation with a variable displacement engine using cylinder deactivation (CDA) or skip fire, including dynamic skip fire and/or multi-level skip fire.

A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit and a misfire determination unit. The misfire determination unit includes first to third determination units. The first determination unit determines whether or not the crankshaft rotation speed fluctuation physical quantity acquired by the crankshaft rotation speed fluctuation physical quantity acquisition unit is greater than a set physical quantity determination reference. The second determination unit determines whether or not a fluctuation pattern constituted by a physical quantity and the crankshaft rotation speed fluctuation physical quantity acquired at least before or after the physical quantity falls within a set misfire pattern range. The third determination unit determines whether a misfire determination is to be set as effective or not, based on results of determination by the first and second determination units.

A vehicle learning system includes a first execution device mounted on a vehicle, a second execution device outside the vehicle, and a storage device. The storage device stores mapping data including data, which is learned by machine learning and defines mapping that receives input data based on a detection value of an in-vehicle sensor and outputs an output value. The first execution device and the second execution device execute, in cooperation with each other, an acquisition process of acquiring input data, a calculation process of calculating an output value with the input data as an input of the mapping, and a relationship evaluation process of evaluating a relationship between a predetermined variable different from a variable corresponding to the output value and accuracy of the output value. The first execution device executes at least the acquisition process, and the second execution device executes at least the relationship evaluation process.