Abstract: A method for operating an oil circuit for a vehicle, the oil circuit being configured to supply oil to an internal combustion engine, wherein the oil circuit includes an oil cooler, and wherein at least one temperature sensor measures the temperature of the oil flowing through the oil circuit, downstream of the oil cooler and upstream of the internal combustion engine, the temperature sensor being connected for signaling purposes to a regulating and/or control device, includes: controlling and/or regulating, by the regulating and/or control device, the temperature of the oil flowing through the oil circuit, such that the temperature measured by the temperature sensor has a defined target temperature value; and setting and/or adjusting, by the regulating and/or control device, as a function of a drive power of the internal combustion engine, the defined target temperature value so as to reduce fuel consumption of the internal combustion engine.

Abstract: A control device includes an electronic control unit. During deceleration of the engine, when a temperature of a three-way catalyst is equal to or higher than a predetermined temperature and execution conditions of fuel cut processing are established, the electronic control unit executes first control for closing an exhaust shutoff valve, while fuel injection and ignition are continued. When the exhaust shutoff valve reaches the closed state in the first control, the electronic control unit executes second control for bringing the engine into an intake control state in which the intake throttle is closed and an EGR valve is in a predetermined open state. In the second control, the electronic control unit executes the fuel cut processing by stopping the ignition before the engine is brought into the intake control state and stopping the fuel injection after the engine is brought into the intake control state.

Abstract: Methods and systems are provided for conducting measurements of relative humidity via the use of either an ultrasonic sensor positioned on the vehicle, or via another sensor. In one example, responsive to a request for a relative humidity measurement and an indication of fueled engine operation, the ultrasonic sensor may be utilized, whereas responsive to an indication of non-fueled engine operation, another sensor may be utilized. In this way, robust measurement of relative humidity with desired accuracy may be actively determined, rather than opportunistically, and such measurements of relative humidity may be utilized to adjust vehicle operating parameters, which may improve overall vehicle operation.

Abstract: Methods and systems are provided for adjusting engine operation based on wirelessly received weather data in conjunction with engine sensor outputs. In one example, a method may comprise receiving a first measurement of a weather parameter from one or more engine sensors and a second measurement of the weather parameter from weather data, the weather data provided by a wireless weather service. The method may further comprise determining accuracies for the first and second measurements, generating an estimate of the weather parameter based on the accuracies of the first and second measurements, and adjusting at least one engine operating parameter based on the generated estimate.

Abstract: A model generating device for generating model data regarding an operation state of a target object to be controlled, includes a memory and a processor coupled to the memory and configured to acquire first measurement data regarding the operation state of the target object under each of a plurality of measurement conditions set in a first sequence, acquire second measurement data regarding the operation state of the target object under each of the plurality of measurement conditions set in a second sequence different from the first sequence, estimate third measurement data indicating the operation state in a case where the target object enters a steady state in each of the plurality of measurement conditions, based on the first measurement data and the second measurement data, generate the model data regarding the operation state of the target object based on the third measurement data, and output the model data.

Abstract: A method for adjusting an actual value of a quantity of fuel injected into an internal combustion engine of a motor vehicle to a target value is provided, wherein a deviation of the actual quantity of fuel injected from the target value is determined based on a ratio of the component of the combusted quantity of gas in the induction system to the concentration of oxides of nitrogen in the exhaust system and the injected quantity of fuel is readjusted according to the deviation. Furthermore, an arrangement for carrying out the method is provided.

Abstract: A control system for an internal combustion engine, which is capable of quickly and properly ensuring excellent fuel economy of the engine even when atmospheric pressure has changed. The control system includes an ECU. The ECU performs weighted average calculation on lowland map values and highland map values, based on atmospheric pressure, to thereby calculate map values of a demanded torque that minimize a fuel consumption ratio of the engine in the atmospheric pressure, and calculates engine demanded output. The ECU calculates demanded torque and demanded engine speed using the map values and the engine demanded output, respectively. The ECU controls the engine using the demanded torque.

Abstract: Methods and systems are provided for on-board diagnostics of an exhaust gas recirculation system. In one example, a method may include dynamically estimating upper and lower EGR limits based on a commanded EGR flow and estimating a ratio of accumulated difference between a measured EGR flow and one of the upper and lower EGR limits to accumulated commanded EGR flow, over a duration of time. EGR system degradation may be indicated in response to the ratio being higher than a threshold.

Abstract: An EGR control device includes an estimate EGR ratio calculating portion adapted to calculate an estimate EGR ratio from a fresh air flow amount at a joining portion with the EGR passage of an intake passage and an EGR gas amount passing through the EGR valve, and a joining portion EGR ratio estimating portion adapted to correct an estimate EGR ratio on the basis of a gaseous state inside the introduction passage when the EGR valve switches from a closed state to an open state, to calculate a joining portion EGR ratio being a proportion of an EGR gas amount with respect to fresh air in the joining portion.

Abstract: In an engine control device, a saturated water vapor pressure Ps is calculated from an intake temperature detected by an intake air temperature sensor. A water vapor partial pressure is worked out from the saturated water vapor pressure and humidity detected by a humidity sensor. A specific humidity q and a molar fraction are worked out from the water vapor partial pressure and an atmospheric pressure detected by an atmospheric pressure sensor. A moist air amount is calculated from an intake air amount detected by an AFS on the basis of the molar fraction, and a dry air amount is calculated from this moist air amount on the basis of the specific humidity. A fuel injection amount, an ignition timing, and a target throttle opening are then calculated on the basis of various operation information, using the moist air amount, the dry air amount, and the specific humidity.

Abstract: In response to decrease of a requested torque to a reference value or smaller, a value of a virtual air-fuel ratio that is used in calculation of a target air amount for achieving the requested torque is changed from a first air-fuel ratio to a second air-fuel ratio that is leaner than the first air-fuel ratio. The target air amount is calculated backwards from the requested torque by using the virtual air-fuel ratio. After the value of the virtual air-fuel ratio is changed from the first air-fuel ratio to the second air-fuel ratio, the target air-fuel ratio is switched from the first air-fuel ratio to the second air-fuel ratio. A target EGR rate is calculated by using the virtual air-fuel ratio. The target EGR rate is preferably determined by minimum value selection between a first target value of an EGR rate that is calculated by using the virtual air-fuel ratio, and a second target value of the EGR rate that is calculated by using the target air-fuel ratio.

Abstract: A method of operating an dedicated exhaust gas recirculation engine including a water gas shift catalyst by supplying ambient air and fuel to a dedicated cylinder at a first fuel to air equivalence ratio in the range of greater than 1.0 to 1.6 for a first number of engine cycles and, for a second number of engine cycles, supplying ambient air and fuel to the dedicated cylinder at a second fuel to air equivalence ratio in the range of 0.7 to less than 1.0. During the second number of cycles, spark timing of the dedicated cylinder is adjusted and a time delay when exhaust recirculated from the dedicated cylinder will be inducted into the cylinders is determined. At the end of the time delay, a second spark timing of the main cylinder is adjusted and the amount of fuel supplied to the main cylinders is increased.

Abstract: Described is a method for controlling an internal combustion engine, wherein an ignition control device is prompted by control signals of an engine control device to activate an ignition device by means of which an ignition of a fuel-air mixture in a cylinder of the internal combustion engine is affected. It is provided according to this disclosure, that the engine control device communicates a target ignition angle or information about an operating condition of the internal combustion engine to the ignition control device, and the ignition control device sets an operating parameter of the ignition device in dependence on the target ignition angle or the information about the operating condition of the internal combustion engine.

Abstract: Methods and systems are provided for indicating water at an oxygen sensor based on power consumption of a heating element of the oxygen sensor. In one example, water may be indicated at an oxygen sensor positioned in an intake of an engine responsive to power consumption of the heating element of the oxygen sensor increasing above a baseline level. Engine operating parameters may then be adjusted based on the water indication and the power consumption.

Abstract: Provided is an exhaust gas recirculation device for an internal combustion engine, the device being configured, without an increase in the number of parts, so that stress concentrated on an EGR pipe and on the connection section thereof is dispersed. The upstream EGR pipe extends substantially upward from the first connection section and has four bends provided between the first connection section and the second connection section. Among the four bends, the smallest-angle bend having the smallest bend angle is disposed at a position having a substantially equal distance from both the first connection section and the second connection section.

Abstract: An internal combustion engine control apparatus is provided that can prevent the operation of an internal combustion engine from becoming unstable even when the ignition apparatus fails, that can prevent the components of the exhaust gas from being deteriorated, and that can suppress the exhaust amount of environmental load substances from increasing. A diagnosis unit is provided that determines whether or not an energy supply unit is normally supplying energy to a conductive path formed in the gap of an ignition plug; a control unit controls an EGR unit in accordance with the result of a diagnosis by the diagnosis unit so as to control the amount of burned gas to be recirculated to the internal combustion engine.

Abstract: A vehicle is provided with an engine, an H2 and CO tank, a CO2 reclaimer, an electrolytic solution tank, an electrolyzer, a water tank and the like. During operation of the engine, an exhaust gas is introduced into an absorbing liquid in the CO2 reclaimer so as to recover CO2 in the exhaust gas and to store the same in the electrolytic solution tank. While supplying the absorbing liquid having absorbed CO2 and water to the electrolyzer from the electrolytic solution tank and the water tank, respectively, electric power is supplied to the electrolyzer. As a result, a mixed gas composed of CO and H2 from CO2 and water. The generated mixed gas is temporarily stored in the H2 and CO tank and is supplied to the engine.

Abstract: Two-stage exhaust apparatus for a reciprocating internal combustion engine having one or more cylinders each with at least one piston and at least one exhaust port, the apparatus including a first-stage jet port in each cylinder, the jet port configured to open to release high-pressure exhaust gas to a high-pressure motor prior to exhaust-port opening.

Abstract: Methods and systems are provided for adjusting an engine operating parameter based on an output of a humidity sensor during a compressor bypass valve event. When the compressor bypass valve is closed, a current output of the sensor is used for the adjustments. When the compressor bypass valve is opened, such as to mitigate surge, an output of the sensor stored from before the opening of the bypass valve is used for the adjustments.

Abstract: Systems and methods are provided for adjusting an engine powertrain component responsive to ambient humidity, the ambient humidity based on vehicle position in a region, clock time ambient temperature, and historical humidity data for that region for a current time of year. This may be accomplished without relying on a costly, and often, temperamental physical humidity sensor. Training modules and cloud updates may further increase the accuracy of the virtual humidity sensor of the present disclosure.

Abstract: The invention relates to a method and an apparatus for determining an exhaust gas recirculation rate in an internal combustion engine, in which the exhaust gas recirculation rate indicates a proportion of exhaust gas in a gas quantity delivered to a cylinder of the internal combustion engine, and combustion takes place in the cylinder of the engine cyclically during a combustion phase. The method includes the steps of ascertaining a combustion course statement over the course of combustion in the cylinder of the engine, and ascertaining an actual exhaust gas recirculation rate from the combustion course statement with the aid of a predetermined exhaust gas recirculation rate function.

Abstract: An engine control system for a vehicle includes an exhaust gas recirculation (EGR) rate-estimation module and a control module. The EGR rate-estimation module receives a first signal indicating a first relative humidity of a flow of air and a second signal indicating a second relative humidity of a mixed flow of air and exhaust gas. The EGR rate-estimation module determines an estimated EGR rate based on the first relative humidity and the second relative humidity, wherein the estimated EGR rate corresponds to a flow rate of a flow of exhaust gas to an engine. The control module selectively adjusts an engine operating parameter based on the estimated EGR rate.

Abstract: The present invention has an object to enable a torque as required to be realized without being influenced by an operation state of an IN-VVT, which is a variable valve timing mechanism which changes a valve timing of an intake valve. For this purpose, a control device for an internal combustion engine provided by the present invention stores data that defines a relationship between an air quantity and a torque in an MBT in association with the operation state of the IN-VVT, and calculates a target air quantity for realizing a required torque based on the data. The control device calculates an actual air quantity which is actually realized by an operation of a throttle when operating the throttle to realize the target air quantity.

Abstract: A method for managing thermal energy in an internal combustion engine including an exhaust gas recirculation system and an engine cooling system includes recirculating a portion of an exhaust gas through the exhaust gas recirculation system that is in thermal communication with a first side of a thermoelectric device, flowing an engine coolant into thermal communication with a second side of a thermoelectric device, and controlling electric current between an electrical energy storage device and the thermoelectric device to transfer thermal energy between the recirculated exhaust gas and the engine coolant.

Abstract: An engine ECU performs a process including the steps of performing an external EGR and advancing ignition timing of all cylinders of an engine, retarding ignition timing cylinder by cylinder in sequential order when no knocking had occurred before performing the external EGR and advancing the ignition timing and knocking occurred after performing the external EGR and advancing the ignition timing, and determining that a passage provided for a cylinder in which the retardation of ignition timing caused a shift from a state in which knocking occurs to a state in which no knocking occurs is clogged.

Abstract: Because opening of a flow enhancement valve affects not only a flow but also a flow rate, when the opening of the flow enhancement valve is transiently changed, if an ignition correction control is conducted on the basis of a relationship obtained in a steady operation state of the flow enhancement valve opening and the ignition timing, there occurs such a drawback that the ignition timing is set to a retard side or an advance side of the optimal point.

Abstract: An ignition timing control system for an internal combustion engine is provided to ensure stable combustion without causing misfire or knocking, by properly setting ignition timing in the compression stroke injection mode, thereby improving drivability. The ignition timing control system for the engine, that directly injects fuel into the cylinders and that is operated by switching the fuel injection mode between an intake stroke injection mode and a compression stroke injection mode, includes a fuel injection timing-setting device for setting a fuel injection timing according to an engine speed of the engine and a fuel injection amount, a basic value-setting device for setting a basic value of ignition timing according to the engine speed of the engine and the fuel injection timing, and an ignition timing-setting device for setting ignition timing in the compression stroke injection mode by correcting the basic value according to a detected air-fuel ratio.

Abstract: A method for setting an exhaust gas recirculation rate in an engine system having an internal combustion engine, the exhaust gas recirculation rate indicating the portion of the exhaust gas recirculated into one cylinder of the internal combustion engine with regard to the total gas quantity present in the cylinder, including: operating the internal combustion engine according to an input for the exhaust gas recirculation rate, an ignition of an air/fuel mixture being carried out in the cylinder at a certain ignition timing; adjusting the ignition timing in the cylinder of the internal combustion engine; correcting the input for the exhaust gas recirculation rate as a function of a change in an operating behavior of the internal combustion engine due to the ignition timing adjustment.

Abstract: In the present invention, in a control system for a spark ignition internal combustion engine, when a catalyst is not sufficiently active, the ignition timing is advanced to be earlier than MBT to decrease the quantity of hydrocarbons (HC) discharged from the internal combustion engine, and oxygen is supplied to the exhaust gas upstream of the catalyst to thereby oxidize carbon monoxide (CO) discharged from the internal combustion engine. According to this invention, exhaust emissions emitted before activation of the exhaust gas purification apparatus can be decreased as much as possible, and early activation of the catalyst can be achieved by making use of heat generated by oxidation reaction of carbon monoxide (CO).

Abstract: A method is described for operating an engine of a vehicle, the engine having a combustion chamber. The method may include controlling a stability of the vehicle in response to a vehicle acceleration; and adjusting spark timing in the combustion chamber of the engine in response to a knock indication, and further adjusting spark timing in response to the vehicle acceleration to reduce surge.

Abstract: A method is described for operating an engine of a vehicle, the engine having a combustion chamber. The method may include controlling a stability of the vehicle in response to a vehicle acceleration; and adjusting spark timing in the combustion chamber of the engine in response to a knock indication, and further adjusting spark timing in response to the vehicle acceleration to reduce surge.

Abstract: An engine ECU performs a process including the steps of performing an external EGR and advancing ignition timing of all cylinders of an engine, retarding ignition timing cylinder by cylinder in sequential order when no knocking had occurred before performing the external EGR and advancing the ignition timing and knocking occurred after performing the external EGR and advancing the ignition timing, and determining that a passage provided for a cylinder in which the retardation of ignition timing caused a shift from a state in which knocking occurs to a state in which no knocking occurs is clogged.

Abstract: A method for reducing particulate matter emitted by an engine is disclosed. In one example, the start of fuel injection timing is adjusted in response to a change in engine operating conditions. In particular, start of injection timing may be advanced and then retarded to promote fuel vaporization.

Abstract: An oxygen sensor generating an accurate output concerning low-concentration exhaust gas positioned downstream of a three-way catalyst. The oxygen sensor includes an exhaust gas side electrode exposed to an exhaust gas; a reference gas side electrode exposed to a reference gas serving as a reference for oxygen concentration; and an electrolyte positioned between the exhaust gas side electrode and the reference gas side electrode. Further, a reduction mechanism positioned toward a front surface of the exhaust gas side electrode ensures the ratio of the amount of exhaust gas introduced to the exhaust gas side electrode to the amount of an exhaust gas flow to the outside of the oxygen sensor is smaller than the ratio of the amount of exhaust gas introduced to an electrode for the air-fuel ratio sensor to the amount of an exhaust gas flow to the outside of the air-fuel ratio sensor.

Abstract: A multi-cylinder engine includes an EGR mechanism for introducing exhaust gas into intake air, and is capable of a partial cylinder operation in which combustion in a part of the cylinders is halted. The multi-cylinder engine includes an EGR rate control unit for setting an introduction rate at which the exhaust gas is introduced into the intake air to be lower in a first partial cylinder operating state in which the ignition intervals are unequal, than in a second partial cylinder operating state, in which ignition intervals among a plurality of operating cylinders are equal.

Abstract: A method is provided for operating a homogeneous charge compressed ignition engine in which a mixture gas is burned by compression ignition in a combustion chamber of a cylinder, fuel and air being previously mixed to produce the mixture gas. The homogeneous charge compressed ignition engine includes an ignition plug, which performs spark ignition to the mixture gas. An advance-angle limit and a delay-angle limit of spark ignition timing are set. The compression ignition of the mixture gas is able to be induced at the spark ignition timing. The spark ignition is supplementarily performed to the mixture gas according to an operating condition between the advance-angle limit and the delay-angle limit.

Abstract: A spark-ignition gasoline engine having at least a spark plug, the engine including an engine body having a geometrical compression ratio set at 14 or more, and an intake valve and an exhaust valve provided, respectively, in intake and exhaust ports connected to each of a plurality of cylinders of the engine body. The intake and exhaust valves are adapted to open and close corresponding respective ones of the intake and exhaust ports. The engine further includes an operation-state detector adapted to detect an operation state of the engine body and a control system adapted, based on detection of the operation-state detector, to perform at least an adjustment control of an ignition timing of the spark plug, the control system being operable, when an engine operation zone is a high-load operation zone including a wide open throttle region within at least a low speed range, to retard the ignition timing to a point within a predetermined stroke range just after a top dead center of a compression stroke.

Abstract: An internal combustion engine apparatus provided with an internal combustion engine in which ignition timing can be adjusted and which has attached thereto an exhaust gas recirculation device that recirculates exhaust gas to an intake side, a control method for the internal combustion engine apparatus, and a hybrid vehicle are provided.

Abstract: Various systems and methods are described for controlling an engine in a vehicle which includes an exhaust passage and an exhaust gas recirculation system. One example method comprises adjusting an engine operating parameter based on an exhaust gas recirculation amount, the exhaust gas recirculation amount based on a first humidity and a second humidity, the first humidity generated from a first humidity sensor at a first location and the second humidity generated from a second humidity sensor located in the exhaust passage of the engine.

Abstract: An abnormality determination device of a cylinder pressure sensor calculates a gain (sensing sensitivity coefficient) and an offset (bias) indicating an output characteristic of the cylinder pressure sensor. The device determines existence or nonexistence of an abnormality in the gain and the offset respectively. When the device determines that the abnormality exists, the device performs failsafe processing set in modes different from each other between the case of the abnormality in the gain and the case of the abnormality in the offset. As the failsafe processing in the case of the abnormality in the gain, the device performs processing for substantially prohibiting usage of a sensor value of the cylinder pressure sensor in control (fuel injection timing control) by using an alternative value (specified value) instead of the sensor value of the cylinder pressure sensor.

Abstract: Disclosed is a spark-ignition gasoline engine, which comprises control means operable, when an engine operation zone is a high-load operation zone including a WOT region within at least a low speed range, to adjust a closing timing of an intake valve in such a manner as to maintain an effective compression ratio at 13 or more, and retard an ignition timing to a point within a predetermined stroke range just after a top dead center of a compression stroke, wherein the effective compression ratio is calculated based on an intake-valve closing timing defined by a valve lift amount of 1 mm. The present invention can provide a spark-ignition gasoline engine having both a low-cost performance and a high engine-power performance even in a high-load operation zone (particularly WOT region) in a low speed range.

Abstract: Systems and methods for controlling automotive powertrains using a distributed control architecture are disclosed. A distributed control system may include a supervisory control unit for controlling one or more powertrain subsystems, and one or more subsystem control units in communication with the supervisory control unit. The supervisory control unit can be configured to execute a central optimization algorithm that computes variables from across multiple powertrain subsystems, and then outputs a number of globally approximated command values to each associated subsystem control unit. In some embodiments, the central optimization algorithm can be configured to solve a global cost function or optimization routine. One or more of the subsystem control units can be configured to execute a lower-level algorithm or routine, which can comprise a higher-fidelity model than that used by the central optimization algorithm.

Abstract: A control system for an internal combustion engine having at least one fuel injection valve for injecting fuel into a combustion chamber of the engine, and an exhaust gas recirculation mechanism for recirculating a portion of exhaust gases from the engine to the combustion chamber. The exhaust gas recirculating mechanism includes an exhaust cooler for cooling the recirculated exhaust gases. A target ignition timing of the fuel injected by the fuel injection valve is calculated. An actual compression ignition timing of the fuel injected by the fuel injection valve is detected. Operation of the exhaust cooler is controlled based on the target ignition timing and the actual compression ignition timing.

Abstract: A method and system for use with flexible fuel engines capable of operating with arbitrary mixtures of gasoline and alternative fuel. The engine is equipped with an EGR loop and a control system, such that, as the relative amount of alternative fuel decreases, the amount of EGR provided to the engine increases.

Abstract: An acceleration request is detected in accordance with an accelerator opening PA (time t3 in FIG. 5B). If the detected acceleration request is a moderate acceleration request, an idle opening TA0 is set as an actual throttle opening TA (FIG. 5E), and a request for retarding an intake valve timing VVT is issued (FIG. 5D). Recovery from fuel cut-off is achieved at time t4 at which a misfire limit value (combustion assurance VVT value L) is reached by an actual VVT value (FIG. 5A).

Abstract: In an NOx discharge quantity estimation method for an internal combustion engine equipped with an EGR apparatus, the gas components (e.g., oxygen molecules and NOx) of intake gas taken into a combustion chamber are assumed to be uniformly distributed throughout the entire region of the combustion chamber. Under such assumption, the combustion chamber is divided into a combustion region (region B) and a non-combustion region (region A) by making use of the ratio of the “mass of oxygen consumed as a result of combustion” to the “total mass of oxygen taken in the combustion chamber.

Abstract: This feature of the present invention comprises an ignition diagnostics and feedback control system based upon detected ionization current in an individual cylinder. The system is divided into two subsystems: an ignition diagnostics subsystem and an ignition feedback control system subsystem. The ignition diagnostics subsystem comprises an ignition system diagnostics, a misfire detector, a knock detector, and a robust multi-criteria minimum timing for best torque MBT timing estimator. The ionization feedback control subsystem comprises five main subsystems: a closed loop cold start retard spark control using ionization feedback, a closed loop MBT timing control using ionization feedback, a closed-loop individual cylinder air to fuel ratio balancing control system, an optimal wide open throttle air/fuel ratio control, and an exhaust gas control using a spark plug ionization signal.

Abstract: A control apparatus operates a compression ignition internal combustion engine by switching between spark ignition combustion using an ignition device and compression ignition combustion which self-ignites a mixture by piston compression. Variable valve mechanisms vary at least one of the valve timings and valve lifts of an intake valve and an exhaust valve. Intake air is regulated to vary the amount of air intake into a combustion chamber on the upstream side of a combustion chamber inlet of the compression ignition internal combustion engine. The variable valve mechanisms and the intake air regulation are controlled during the compression ignition combustion so as to perform the compression ignition combustion.

Abstract: This feature of the present invention is a robust multi-criteria minimum timing for the best torque (MBT) timing estimation method and apparatus utilizing different ionization signal waveforms that are generated under different engine operating conditions. This feature of the present invention determines and combines multiple MBT timing criteria to increase the reliability and robustness of MBT timing estimation based upon spark plug ionization signal waveforms. In a preferred embodiment, the present invention combines MBT timing estimation criteria comprising a maximum flame acceleration location, a 50% burn location, and a second peak location.

Abstract: A combustion variation value is detected, and a function that uses the detected combustion variation value is added to CVAR(i?1) to obtain CVAR(i); and using the resulting value, an exhaust gas recirculation amount and an ignition timing are obtained. A combustion variation is detected, and if the detected combustion variation value is equal to or greater than a predetermined value, the value of flag is set to be 1, and the exhaust gas recirculation amount and the ignition timing are reset to previous values. If the detected combustion variation value is less than the predetermined value, the value of the flag is set to be zero, and a current combustion variation manipulation correcting amount CVAR(i) is updated. If the value of flag is 1, the process is immediately terminated.