Abstract: A straddled vehicle engine unit including an internal combustion engine and a misfire detection device. The internal combustion engine has a crankshaft, and a crank angle signal output unit that periodically outputs a crank angle signal in accordance with rotation of the crankshaft. The internal combustion engine is configured to repeat at least two kinds of strokes on a cycle of every 720-degree rotation of the crankshaft. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit configured to acquire a physical quantity related to an amount of fluctuation in a rotation speed of the crankshaft in one kind of stroke, out of the at least two kinds of strokes, based on the crank angle signal from the crank angle signal output unit, and a misfire determination unit configured to perform a misfire determination in response to each acquisition of the crankshaft rotation speed fluctuation physical quantity.

Abstract: An engine misfire detection device is mounted on a hybrid electric vehicle that includes an internal combustion engine and a generator. The internal combustion engine has a plurality of cylinders and a crankshaft and is dedicated to power generation. The generator is connected to the crankshaft via a torsional damper. The engine misfire detection device includes a generator rotation angle sensor and a processor. The generator rotation angle sensor detects the rotation angle of the generator rotating shaft. The processor is configured to execute a misfire detection process. The misfire detection process includes a first misfire detection process of determining that the internal combustion engine has misfired when an amplitude correlation value that correlates with the magnitude of amplitude of rotation speed of the generator rotating shaft and is detected by the generator rotation angle sensor is greater than a determination threshold value.

Abstract: An engine misfire detection device such that an engine misfire state can be accurately detected is obtained. The engine misfire detection device includes an engine rotational speed change amount detector that detects an engine rotational speed change amount, an engine rotational speed change amount threshold setter that sets a threshold with respect to the rotational speed change amount, and a misfire detector that compares the rotational speed change amount and the threshold, carries out a misfire determination on the engine when the rotational speed change amount exceeds the threshold, and carries out a misfire detection, wherein the misfire detector prohibits the misfire determination when a switching between a differentially locked state and an unlocked state is carried out.

Abstract: A vehicle driving device including: a rotary electric machine that is a driving force source of a first wheel and a second wheel; a speed reduction device that reduces a speed of a rotation of the rotary electric machine; and a differential gear device that distributes to the first wheel and the second wheel, a driving force that is transmitted from the rotary electric machine via the speed reduction device.

Abstract: To provide a controller for an internal combustion engine which can determine presence or absence of misfire with good accuracy, even when the rotational variation occurs due to factors other than misfire. A controller for an internal combustion engine calculates, as a reference detection period, the detection period detected within a reference angle interval including a top dead center; calculates a period deviation which is a deviation between the reference detection period and the each detection period; calculates a former period deviation integration value by integrating the period deviation in a former angle interval before the top dead center; calculates a later period deviation integration value by integrating the period deviation in a later angle interval after the top dead center; and determines presence or absence of misfire in the combustion stroke based on the former period deviation integration value and the later period deviation integration value.

Abstract: An unequal-interval combustion engine misfire-determination device determines whether a misfire has occurred in an unequal-interval combustion engine including a plurality of cylinders in which combustion occurs at unequal intervals.

Abstract: A misfire determination device includes: a combustion fluctuation canceled value acquisition unit that acquires a first combustion fluctuation canceled value corresponding to a first angle position and a second combustion fluctuation canceled value corresponding to a second angle position; a combustion fluctuation manifested value calculation unit that calculates a first fluctuation manifested value by removing the first combustion fluctuation canceled value from a rotation speed at the first angle position, and calculates a second fluctuation manifested value by removing the second combustion fluctuation canceled value from a rotation speed at the second angle position; a first-order difference calculation unit that calculates a first-order difference between the first fluctuation manifested value and the second fluctuation manifested value; and a specific cylinder misfire determination unit that determines a misfire in a specific cylinder by using the first-order difference.

Abstract: To provide a controller and a control method for an internal combustion engine capable of detecting misfire with good accuracy by simple calculation, even when a vibration in a period of about several strokes occurs in the crankshaft. A controller and a control method for an internal combustion engine detects crank angle based on an output signal of the specific crank angle sensor 6, and calculates a crank angle speed, a crank angle acceleration, and a crank angle jerk which is a time change rate of the crank angle acceleration; calculates a fluctuation amount of the crank angle jerk in a determination period which is set corresponding to a one combustion stroke based on the crank angle jerk; and determines a presence/absence of misfire in the one combustion stroke based on the fluctuation amount of the crank angle jerk.

Abstract: A misfire detecting device for an engine is provided, which includes a processor configured to execute a cylinder operation controlling module to switch an engine operation mode from an all-cylinder operation to a reduced-cylinder operation in which operation of one or some of cylinders are suspended, when an execution condition of the reduced-cylinder operation is satisfied, a misfire detecting module to detect a possibility of misfire occurrence based on an angular speed variation of the engine, and a centrifugal damping part configured to reduce vibration caused by the engine. When a possible misfire state is detected by the misfire detecting module during the reduced-cylinder operation, the cylinder operation controlling module executes an operating-cylinder increase control in which the number of operating cylinders is increased. When the possible misfire state is continuously detected after the operating-cylinder increase control, the misfire detecting module detects the engine misfire.

Abstract: An engine system includes: an engine including a plurality of cylinders; an EGR passage including EGR branch passages each configured to recirculate part of exhaust gas into an intake port of a corresponding one of the plurality of cylinders; an EGR valve configured to be capable of adjusting an EGR flow rate; and an ECU configured to control the EGR valve. When an engine rotation fluctuation amount in an EGR OFF state is less than a first determination value, and when the engine rotation fluctuation amount in an EGR ON state is greater than a second determination value, the ECU imposes an EGR restriction for restricting the EGR flow rate. When it is determined that the engine rotation fluctuation amount in the EGR ON state is greater than a third determination value less than the second determination value after the EGR restriction is imposed, the ECU continues the EGR restriction.

Abstract: A control device for a rotating element rotated by a four-stroke engine has a high degree of freedom in the choice of an apparatus to which the control device is applicable. The control device includes a rotation speed acquisition unit configured to obtain a rotation speed of the rotating element rotated by the four-stroke engine, and an undulation detection unit configured to, based on the rotation speed obtained by the rotation speed acquisition unit, detect a periodic undulation contained in a rotation fluctuation of the four-stroke engine, the periodic undulation having an angular period longer than a crank angle corresponding to four strokes.

Abstract: A diagnostic tool configured to retrieve mode 6 cylinder misfire data from an engine controller using physical addressing of the engine controller. The mode 6 data is retrieved on a continuous and dynamic basis instead of a snapshot. The retrieved mode 6 data may be displayed on a GUI and may also contain other mode 6 data such as throttle position sensor, engine RPM and mass air flow.

Abstract: A vehicle drive system includes an internal combustion engine, a clutch, an engine rotation speed detector, an output shaft rotation speed detector, and a processor. The internal combustion engine includes cylinders and a crankshaft. The clutch is connected to the crankshaft via a torsion element and includes an output shaft. The engine rotation speed detector detects a crankshaft rotation speed. The output shaft rotation speed detector detects an output shaft rotation speed. The processor is configured to calculate a torque generated in each of the cylinders based on the crankshaft rotation speed. The processor is configured to decrease transmission torque of the clutch so that a difference between the crankshaft rotation speed and the output shaft rotation speed to be a target value when misfiring occurs. The processor is configured to identify a misfiring cylinder among the cylinders based on the torque calculated while the transmission torque is decreased.

Abstract: A misfire detecting apparatus is provided wherein a misfire is detected based on a rotational speed parameter indicative of a rotational speed of an internal combustion engine. An average change amount of the rotational speed parameter in a first predetermined period and an inertia speed changing component which is generated with rotation of the engine are calculated, and a first corrected rotational speed parameter is calculated by correcting the rotational speed parameter according to the average change amount and the inertia speed changing component.

Abstract: A system for the misfire diagnosis includes an angular velocity sensor acquiring an angular velocity of an engine and an acceleration sensor acquiring an acceleration according to vertical vibration of a vehicle. A diagnosis unit is configured to compare the acceleration with an acceleration threshold to determine whether the vehicle is driven on a rough road and to diagnose whether misfire occurs. A threshold setting unit is configured to acquire misfire diagnosis results in a first test environment in which the vehicle is driven on the rough road without forcible misfire and in a second test environment in which the vehicle is driven on the rough road while the forcible misfire occurs. The threshold setting unit is further configured to calculate a misfire misdiagnosis rate and to update the acceleration threshold.

Abstract: Methods and systems are described for detecting valve actuation faults in internal combustion engines operating in a skip fire operational mode. In one aspect, a torque model is used to estimate an expected net torque during a selected operating window. The torque model considers an expected torque contribution from each of the cylinders and accounts for the effects of specific skip fire firing decisions that affect the expected torque contribution from each cylinder. A parameter indicative of the actual engine torque is also measured. Valve actuation faults can then be identified based at least in part on a comparison of the measured parameter to an expected parameter value that is based at least in part on the expected net torque. With the described approaches, the occurrence of the valve actuation fault can be made within one engine cycle of the initial occurrence of the fault.

Abstract: Methods and systems are provided for an engine including a crankcase. A condition of the engine may be diagnosed based on frequency content of crankcase pressure. Different types of degradation may be distinguished based on a frequency content of multiple frequencies of the crankcase pressure. Thus, a degraded engine component may be identified in a manner that reduces service induced delay.

Abstract: A method for transmitting a sequence of data blocks to be transmitted includes: one first piece of authentication data and one second piece of authentication data different from the first are formed relative to a selected data block; the selected data block, the first piece of authentication data and the second piece of authentication data are transmitted to a receiver; and the receiver checks (i) a validity of the received data block with the aid of the received first piece of authentication data and (ii) a validity of the received first piece of authentication data with the aid of the received second piece of authentication data.

Abstract: A system and method for controlling a fraction motor in a hybrid vehicle includes varying a traction motor torque in response to an engine cylinder misfire. The traction motor torque is varied to compensate for an engine torque shortfall due to the engine cylinder misfire, reducing a torque imbalance caused by the misfire.

Abstract: When an idle speed control is implemented, an engine speed is computed based on an output signal of a crank angle sensor at a specified processing angle interval, and a time interval corresponding to the specified processing angle interval is computed. Then, the engine speed is filtered at a specified processing time interval, and a feedback amount (throttle opening correction amount) is computed based on a deviation of an engine speed filtered by a filter portion from a target engine speed. A time constant of a filtering processing is established according to the processing angle interval. Therefore, a filtering processing and a feedback control processing are performed in synchronization with each other, and an instability of an output of the feedback control (feedback amount) can be reduced.

Abstract: According to a method and an apparatus of the present invention for diagnosing a fault of an engine, a cranking rotation state is created by rotating a crank shaft while explosions in each cylinder are stopped; a variation of angular velocity of the crank shaft is detected for each cylinder in the cranking rotation state; a cylinder the compression pressure of which is insufficient is detected based on the variation; and if a cylinder indicated as a misfiring cylinder by a fault code is the same as the cylinder detected as being insufficient in compression pressure in the cranking rotation state, the cylinder is specified.

Abstract: A misfire detecting portion executes a misfire detection control that involves evaluating the presence or absence of a misfire in an engine on the basis of an angular speed computed by an angular speed computing portion, and outputting an alert signal to provide notification about a misfire when a misfire is present. A learning portion conducts learning of an operational parameter on the basis of a detection value of a sensor when an engine rotation speed is within a predetermined first range that is larger than a predetermined idling rotation speed. A learning completion evaluating portion evaluates whether learning by the learning portion is completed. A misfire detecting portion conducts misfire detection control under the condition that the learning is completed. The misfire detecting portion does not conduct misfire detection control when the learning is not completed.

Abstract: An abnormality diagnosis apparatus for an internal combustion engine in which a phase of a first valve provided to a first cylinder is modified within a range extending from a first phase to a second phase and a phase of a second valve provided to a second cylinder is modified within the range includes: a rotation variation amount detection unit that detects a rotation variation amount of an output shaft of the internal combustion engine; and a diagnosis unit that adjusts the phase of the first valve and the phase of the second valve to the first phase, and diagnoses the presence of an abnormality on the basis of the detected rotation variation amount of the output shaft of the internal combustion engine in a state where the phase of the first valve and the phase of the second valve are at the first phase.

Abstract: A hybrid powertrain includes an engine, an electric machine, and a transmission. A method to control the powertrain includes monitoring operation of the powertrain, determining whether conditions necessary for growl to occur excluding motor torque and engine torque are present, and if the conditions are present controlling the powertrain based upon avoiding a powertrain operating region wherein the growl is enabled.

Abstract: A first target wheel has an opening and rotates about an axis of rotation to move the opening along a generally circular path. A second target wheel adjacent the first target wheel has a second projection projecting into the opening of the first target wheel with the second projection being movable along the generally circular path. A single sensor is positioned adjacent the generally circular path and senses movement of the opening and the second projection past the sensor. An electronic controller may be used to process signals from the sensor to determine the relative angular difference between the first target wheel and the second target wheel.

Abstract: A method is provided for the detection of a component malfunction along the life of an Internal Combustion Engine. The engine, having at least a cylinder and being controlled by an Electronic Control Unit (ECU), the method includes, but is not limited to defining a pre-determined component malfunction classifier at the start of engine life and setting the classifier as active classifier, defining a validity condition for said active classifier, acquiring in real time a set of relevant signals relating to the operation of the component, feeding the signals to said active classifier in order to determine the occurrence or not of a malfunction of the component, and in case the validity condition of said actual classifier is not satisfied, defining a new classifier using the most recent relevant signals recorded by the ECU, and substituting the actual classifier with the new classifier.

Abstract: A system according to the principles of the present disclosure includes a threshold determination module and a misfire detection module. The threshold determination module determines at least one of an acceleration threshold and a jerk threshold based on a misfire type. The misfire detection module detects a misfire in a cylinder of an engine when: (i) crankshaft acceleration is less than the acceleration threshold; and/or (ii) crankshaft jerk is less than the jerk threshold. Crankshaft jerk is a derivative of crankshaft acceleration with respect to time.

Abstract: A misfire detecting portion executes a misfire detection control that involves evaluating the presence or absence of a misfire in an engine on the basis of an angular speed computed by an angular speed computing portion, and outputting an alert signal to provide notification about a misfire when a misfire is present. A learning portion conducts learning of an operational parameter on the basis of a detection value of a sensor when an engine rotation speed is within a predetermined first range that is larger than a predetermined idling rotation speed. A learning completion evaluating portion evaluates whether learning by the learning portion is completed. A misfire detecting portion conducts misfire detection control under the condition that the learning is completed. The misfire detecting portion does not conduct misfire detection control when the learning is not completed.

Abstract: A combustion diagnosis device for a diesel engine having a plurality of cylinders, including an engine speed sensor for detecting a rotational speed of each cylinder, an injection correction amount calculation unit for calculating an amount of correction for fuel injection of each cylinder in accordance with the engine speed sensor, a rotational fluctuation calculation unit for calculating a rotational fluctuation of each cylinder in accordance with the engine speed sensor, and a combustion state determination unit for determining a combustion state of a determination-target cylinder in accordance with the rotational fluctuation when the correction amount calculated by the injection correction amount calculation unit reaches an upper limit threshold value.

Abstract: When a rotation fluctuation amount of an engine exceeds a predetermined threshold, it is determined that there is a possibility that a misfire has occurred. Then, when a rotation fluctuation pattern of the engine coincides with a first rotation fluctuation pattern, it is determined that a misfire has occurred; whereas, when the rotation fluctuation pattern does not coincide with the first rotation fluctuation pattern, it is determined whether the rotation fluctuation pattern coincides with a specific rotation fluctuation pattern in consideration of a lock-up state of a lock-up clutch or whether an engine rotational speed is lower than a threshold. When the determination is affirmative, occurrence of a misfire is determined on the basis of whether the rotation fluctuation pattern of the engine coincides with a second misfire determination pattern that is defined to be smaller in variation of a rotation fluctuation amount than the first rotation fluctuation pattern.

Abstract: A method of detecting a misfire of an engine includes determining a range of sub-harmonic frequencies of one of a crankshaft sensor signal and an engine speed signal. The range of sub-harmonic frequencies is determined based on a fundamental frequency. The sub-harmonic frequencies are less than the fundamental frequency. Frequency content magnitudes are generated based on the range of the sub-harmonic frequencies and a Discrete Fourier Transform of at least one of the crankshaft sensor signal and an engine speed signal. An energy from velocity non-uniformity (EVN) signal is generated based on the frequency content magnitudes and the range of the sub-harmonic frequencies. The misfire is detected based on the EVN signal and a misfire threshold.

Abstract: A control module for a vehicle includes a time recording module that stores timestamps that correspond to each of N teeth of a target wheel of the vehicle in memory. N is an integer. A position module generates M angular positions based on the timestamps. M is an integer greater than one. Each of the M angular positions corresponds to a space between adjacent ones of the N teeth. A position estimator determines position of the target wheel based on the M positions.

Abstract: An engine includes an angular velocity detecting means 10 for detecting a rotation angular velocity of a crankshaft 11 of the engine, a torque generated by the engine detecting means for detecting a variability of the angular velocity amplitude obtained by the angular velocity detecting means 10 as the variability of the torque generated by the engine. The engine compensates a fuel injection quantity by comparing the angular velocity amplitude detected by the angular velocity detecting means with the adequate angular velocity amplitude.

Abstract: A misfire detecting device is provided for a water jet propulsion watercraft in which a propulsion unit operates through an operation of an engine to propel the water jet propulsion watercraft. The misfire detecting device includes injectors arranged to inject fuel into the engine under a fuel injection amount adjusting control implemented by an electric control device, ignition plugs arranged to ignite the fuel injected into the engine from the injectors to operate the engine, an oxygen sensor arranged to detect that a misfire occurs in the engine, a warning lamp and buzzer arranged to inform that the misfire occurs, etc. The misfire detecting device prevents the warning lamp and the buzzer from informing the warning if the misfire is caused through the control by the electric control device.

Abstract: A misfire detection system monitors engine speed fluctuations in the engine rotation frequency domain and identifies misfire when a phase angle locks onto a stable value rather than fluctuating randomly. After misfire detection, the system also performs cylinder or cylinder pair identification using predefined phase angle regions, where the identification process incorporate knowledge of what phase angle region a locked phase angle falls within.

Abstract: An on-board diagnostic system of a vehicle comprises disabling diagnostic operation, such as a misfire monitor, based on road roughness. In one example, the disabling of the diagnostic operation is based on brake actuation and degradation of an anti-lock braking system.

Abstract: A method of detecting a misfire of an engine includes determining a range of sub-harmonic frequencies of one of a crankshaft sensor signal and an engine speed signal. The range of sub-harmonic frequencies is determined based on a fundamental frequency. The sub-harmonic frequencies are less than the fundamental frequency. Frequency content magnitudes are generated based on the range of the sub-harmonic frequencies and a Discrete Fourier Transform of at least one of the crankshaft sensor signal and an engine speed signal. An energy from velocity non-uniformity (EVN) signal is generated based on the frequency content magnitudes and the range of the sub-harmonic frequencies. The misfire is detected based on the EVN signal and a misfire threshold.

Abstract: The engine misfire detection process according to one aspect of the invention first makes tentative detection on the occurrence or the non-occurrence of an engine misfire in execution of both vibration control and rotation speed control. In response to the tentative detection of an engine misfire, the engine misfire detection process subsequently makes final detection on the occurrence or the non-occurrence of an engine misfire. In the event of no final detection of an engine misfire, the engine misfire detection process makes tentative detection and final detection on the occurrence or the non-occurrence of an engine misfire in prohibition of the vibration control. In the event of still no final detection of an engine misfire, the engine misfire detection process makes tentative detection and final detection on the occurrence or the non-occurrence of an engine misfire in further prohibition of the rotation speed control.

Abstract: A method for determining the angular speed of a drive shaft of an internal combustion engine at each tooth event of a phonic wheel presenting a number N of teeth includes detecting the angular amplitude for each tooth; detecting the time of each tooth; and determining the raw angular speed of each tooth according to the corresponding angular amplitude and time. For each tooth a compensation value is determined which represents the difference between the actual angular amplitude of the tooth and the theoretic angular amplitude of the tooth; and determining the angular speed of each tooth by correcting the raw angular speed based on the corresponding compensation value.

Abstract: A damper post-stage rotation speed in a post-stage of a damper calculated from motor rotation speeds and an engine rotation speed are used to calculate a resonance influence component, and the resonance influence component is subtracted from the engine rotation speed to calculate a determination rotation speed. Then, the determination rotation speed is used to determine a misfire of an engine. This allows determination of the misfire of the engine with higher accuracy even if resonance caused by torsion of the damper occurs.

Abstract: A misfiring cylinder identifying apparatus for a multiple cylinder internal combustion engine is provided with a determining portion that determines whether a plurality of cylinders is misfiring, and an identifying portion that identifies two cylinders among the plurality of cylinders in the order of the revolution speed fluctuation from largest as the misfiring cylinders when it is determined that the plurality of cylinders is misfiring.

Abstract: The engine misfire detection process of the invention sets a first threshold value and second threshold values to be referred to for detection of an engine misfire and detects an engine misfire based on the settings of the first threshold value and the second threshold values and 360-degree differences. The engine misfire detection process of the invention detects the occurrence of an engine misfire at each gear position of the transmission by taking into account the varying effects of the operating conditions of a motor the transmission, and a planetary gear mechanism on the crankshaft of the engine.

Abstract: In a misfire detection apparatus and method that detects a misfire in an internal combustion engine with cylinders provided in a vehicle, it is determined that a misfire occurs in the engine, if a first condition and a second condition are satisfied; the first condition is a condition that a rotational speed of an output shaft of the engine decreases by an amount equal to or larger than a first change amount during a time period from a compression top dead center in a first cylinder to the compression top dead center in a second cylinder; and the second condition is a condition that the rotational speed of the output shaft increases by an amount equal to or larger than a second change amount during a time period from the compression top dead center in the second cylinder to the compression top dead center in a third cylinder.

Abstract: When an operating state constituted of a rotation speed Ne and torque Te of an engine belongs in a resonance region in a post-stage including a damper connected to a crankshaft of the engine, a subtraction sine wave for removing an influence by resonance is calculated, and misfire is judged depending on whether or not a variation amount ?F of a rotation speed F after processing, obtained by subtracting the calculated subtraction sine wave from a variation in 30-degree rotation speed N30 which is a rotation speed every time the crankshaft rotates by 30 degrees, is less than a threshold value Fref. Thereby, even when the operating state belongs in the resonance region, misfire can be judged more reliably and more accurately.

Abstract: An internal combustion engine has a plurality of cylinders and an exhaust tract into which a mixture which is situated in the respective cylinder is introduced in the respective discharge strokes. A combustion misfire rate is determined as a function of at least one operating variable of the internal combustion engine. A temperature in the exhaust tract is determined as a function of the combustion misfire rate.

Abstract: When an operating state constituted of a rotation speed Ne and torque Te of an engine belongs in a resonance region in a post-stage including a damper connected to a crankshaft of the engine, a subtraction sine wave for removing an influence by resonance is calculated, and misfire is judged depending on whether or not a variation amount ?F of a rotation speed F after processing, obtained by subtracting the calculated subtraction sine wave from a variation in 30-degree rotation speed N30 which is a rotation speed every time the crankshaft rotates by 30 degrees, is less than a threshold value Fref. Thereby, even when the operating state belongs in the resonance region, misfire can be judged more reliably and more accurately.

Abstract: An influence component N30m of every 30 degrees in a 30 degree rotation speed N30 base as time required for 30 degree rotation of a crankshaft is calculated by using a frequency characteristic of an influence given to a rotation fluctuation of a crankshaft by output torque output from a motor, which is calculated by using a mechanical model and an amplitude P and a phase q at a time of vibration control by the motor, a determination duration T30j is calculated by subtracting an influence component T30m as an inverse number of this from 30 degree duration T30, and misfire of an engine is determined by comparing the calculated determination duration T30j with a threshold value Tref. Thereby, misfire of the engine outputting power to a post-stage via a damper can be determined more reliably and accurately.

Abstract: An internal-combustion-engine misfire determination system includes: detection sections that detects the rotational speeds of the output shaft and the downstream shaft; a rigidity estimation section that performs a rigidity estimation process in which frequency components caused by a resonance due to torsion of the torsion element are extracted from the rotational speeds, and the rigidity of the torsion element is estimated based on a value obtained by comparing amplitudes of both of the extracted frequency components and on the detected output shaft rotational speed; a resonance influence component calculation section that calculates a resonance influence component caused by an influence of the resonance on the output shaft rotational speed; and a misfire determination section that determines the occurrence of the misfire in the internal combustion engine based on a rotational speed for determination that is obtained by subtracting the calculated resonance influence component from the output shaft rotational

Abstract: A misfire determination device for a multi-cylinder internal combustion engine, of which an output shaft is connected, through a torsion element, to a downstream shaft downstream of the torsion element, includes: an first portion for detecting an output shaft rotational speed that is the rotational speed of the output shaft; a second portion for detecting a downstream shaft rotational speed that is the rotational speed of the downstream shaft; a third portion that calculates a component caused by an influence of resonance due to torsion of the torsion element on the output shaft rotational speed, based on the acquired output shaft rotational speed and the acquired downstream shaft rotational speed; and a fourth portion for determining the occurrence of the misfire in the internal combustion engine based on a rotational speed that is obtained by subtracting the calculated component from the detected output shaft rotational speed.

Abstract: At a Lo gear position of a transmission, the engine misfire detection process of the invention sets a first threshold value A1 and second threshold values to be referred to for detection of an engine misfire (steps S220 and S280) and detects an engine misfire based on the settings of the first threshold value A1 and the second threshold values and 360-degree differences ?360 computed from 30-degree rotation times T30 given as a time required for rotation of a crankshaft by every 30 degrees (steps S230 and S290). At a Hi gear position of the transmission, the engine misfire detection process of the invention sets a first threshold value A2, which is to be smaller than the first threshold value A1, and second threshold values (step S330 and S390) and detects an engine misfire based on the settings of the first threshold value A2 and the second threshold values and the 360-degree differences ?360 (step S340 and S400).