A variety of methods and arrangements for detecting misfire and other engine-related errors are described. In one aspect, a window is assigned to a target firing opportunity for a target working chamber. There is an attempt to fire a target working chamber during the target firing opportunity. A change in an engine parameter (e.g., crankshaft angular acceleration) is measured during the window. A model (e.g., a pressure model) is used to help determine an expected change in the engine parameter during the target firing opportunity. Based on a comparison of the expected change and the measured change in the engine parameter, a determination is made as to whether an engine error (e.g., misfire) has occurred.

A variety of methods and arrangements for detecting misfire and other engine-related errors are described. In one aspect, a window is assigned to a target firing opportunity for a target working chamber. There is an attempt to fire a target working chamber during the target firing opportunity. A change in an engine parameter (e.g., crankshaft angular acceleration) is measured during the window. A model (e.g., a pressure model) is used to help determine an expected change in the engine parameter during the target firing opportunity. Based on a comparison of the expected change and the measured change in the engine parameter, a determination is made as to whether an engine error (e.g., misfire) has occurred.

An engine control device includes: a pre-ignition determination module that determines whether an operation state of an engine indicated by a rotation speed detected by a rotation speed detection unit and a load calculated by a load calculating module is in a pre-ignition occurring region; a catalyst protection determination module that determines whether the operation state of the engine is in a catalyst protection region; and a fuel cut execution control module that stops a fuel supplied to the engine, when a remaining amount of a fuel tank is determined to be smaller than a tank threshold value and the operation state is determined to be in the pre-ignition occurring region, and when the remaining amount of the fuel tank is determined to be smaller than the tank threshold value and the operation state is determined to be in the catalyst protection region.

An engine control device includes: a pre-ignition determination module that determines whether an operation state of an engine indicated by a rotation speed detected by a rotation speed detection unit and a load calculated by a load calculating module is in a pre-ignition occurring region; a catalyst protection determination module that determines whether the operation state of the engine is in a catalyst protection region; and a fuel cut execution control module that stops a fuel supplied to the engine, when a remaining amount of a fuel tank is determined to be smaller than a tank threshold value and the operation state is determined to be in the pre-ignition occurring region, and when the remaining amount of the fuel tank is determined to be smaller than the tank threshold value and the operation state is determined to be in the catalyst protection region.

A drive train abnormality determination device for a straddled vehicle that includes a drive train having a rotator. The drive train abnormality determination device includes an angle signal output unit that periodically outputs an angle signal in accordance with rotation of the rotator, a rotator rotation speed fluctuation physical quantity acquisition unit that acquires a quantity related to a fluctuation in a rotation speed of the rotator, based on the angle signal from the angle signal output unit, a rough road determination unit that determines whether a distribution state or pattern satisfies a predetermined rough road condition, a continuity determination unit that determines whether the rough road condition is continuously satisfied, and a drive train abnormality determination unit that determines, responsive to a determination by the continuity determination unit that the rough road condition is continuously satisfied, that the drive train has an abnormality in its functioning.

A drive train abnormality determination device for a straddled vehicle that includes a drive train having a rotator. The drive train abnormality determination device includes an angle signal output unit that periodically outputs an angle signal in accordance with rotation of the rotator, a rotator rotation speed fluctuation physical quantity acquisition unit that acquires a quantity related to a fluctuation in a rotation speed of the rotator, based on the angle signal from the angle signal output unit, a rough road determination unit that determines whether a distribution state or pattern satisfies a predetermined rough road condition, a continuity determination unit that determines whether the rough road condition is continuously satisfied, and a drive train abnormality determination unit that determines, responsive to a determination by the continuity determination unit that the rough road condition is continuously satisfied, that the drive train has an abnormality in its functioning.

A misfire detecting system for an engine of a vehicle that detects a misfire of the engine is provided. The system includes a sensor configured to detect a wheel speed of the vehicle, a load adjustment device configured to adjust a load of the engine, and a processor. The processor determines whether a wheel slip has occurred by examining whether a change rate of the wheel speed is equal to or greater than a determination reference value, when determining whether the wheel slip has occurred, limits a determination of the misfire of the engine by adjusting the determination reference value higher or lower based on corresponding increases or decreases in a requested load, by applying the adjusted determination reference value, determines that wheel slip has occurred, and based on the wheel slip determination, determines that the misfire has occurred.

A misfire detecting system for an engine of a vehicle that detects a misfire of the engine is provided. The system includes a sensor configured to detect a wheel speed of the vehicle, a load adjustment device configured to adjust a load of the engine, and a processor. The processor determines whether a wheel slip has occurred by examining whether a change rate of the wheel speed is equal to or greater than a determination reference value, when determining whether the wheel slip has occurred, limits a determination of the misfire of the engine by adjusting the determination reference value higher or lower based on corresponding increases or decreases in a requested load, by applying the adjusted determination reference value, determines that wheel slip has occurred, and based on the wheel slip determination, determines that the misfire has occurred.

A CPU substitutes a difference between a crank-side speed that is a rotation speed of a crankshaft and a downstream-side speed that is a speed of a portion, opposite from the crankshaft, in a damper into a differential speed. The CPU calculates a torsion angle through a process of integrating the differential speed. The CPU calculates a torsion speed component that is a speed component of the crankshaft due to torsion of the damper based on a process of integrating a value obtained by multiplying the torsion angle by an elastic modulus, and calculates a time that is a variable indicating a speed of the crankshaft, used to determine a misfire, based on the torsion speed component. The CPU subtracts a value obtained by subtracting an output value of the integrating process, applied to a finite response low-pass filter process, from the output value.

A CPU substitutes a difference between a crank-side speed that is a rotation speed of a crankshaft and a downstream-side speed that is a speed of a portion, opposite from the crankshaft, in a damper into a differential speed. The CPU calculates a torsion angle through a process of integrating the differential speed. The CPU calculates a torsion speed component that is a speed component of the crankshaft due to torsion of the damper based on a process of integrating a value obtained by multiplying the torsion angle by an elastic modulus, and calculates a time that is a variable indicating a speed of the crankshaft, used to determine a misfire, based on the torsion speed component. The CPU subtracts a value obtained by subtracting an output value of the integrating process, applied to a finite response low-pass filter process, from the output value.