Abstract: A system for detecting and controlling misfire and/or AFR imbalance conditions in cylinders of an internal combustion engine having a plurality of cylinders is disclosed.

Abstract: An automobile includes an internal combustion engine having an emission control system, intake manifold and an exhaust manifold. A hydrogen source is positioned to deliver hydrogen to the intake manifold. Hydrogen and gasoline combustion takes place in a cylinder of the internal combustion engine and a catch device is positioned to receive fluid mixture from the exhaust manifold of the internal combustion engine. The catch device condenses the fluid mixture and a filter receives the condensed fluid mixture from the catch device and filters the condensed fluid mixture. A container is positioned to receive the filtered fluid mixture.

Abstract: Systems and methods for operating an engine that includes an oxygen sensor and one or more fuel injectors for each engine cylinder are described. In one example, lines describing a relationship between a fuel mass multiplier and a coefficient of a function describing output of an oxygen sensor to a step change in fuel mass are a basis for determining air-fuel imbalance of engine cylinders.

Abstract: Methods and systems are provided for controlling camshaft phasers of a variable displacement engine. In one example, the engine includes first and second cylinder banks, with the engine being configured to operate in a rolling variable displacement mode. The camshaft phasers are torque actuated camshaft phasers, and a controller of the engine may adjust operation of camshaft phasers at the first cylinder bank differently than camshaft phasers at the second cylinder bank.

Abstract: A method and control device for correcting an output signal of an exhaust gas sensor in an exhaust gas conduit of an internal combustion engine, a secondary air delivery system for delivering air into the exhaust gas conduit being associated with the exhaust gas conduit upstream from the exhaust gas sensor in the flow direction of the exhaust gas. During a measurement of the output signal of the exhaust gas sensor, air is delivered to the exhaust gas conduit via the secondary air delivery system during a correction phase by way of which a correction of the output signal of the exhaust gas sensor is derived. In this operating mode, a defined oxygen content exists in the gas mixture surrounding said sensor, so that the output signal can be compared with reference values.

Abstract: A method for calibrating a drive of a throttle valve of an internal combustion engine of a motor vehicle includes detecting whether the internal combustion engine is currently running or is not running. The method further includes activating the drive to displace the throttle valve into a target position if it is detected that the internal combustion engine is currently not running. The method further includes calibrating a characteristic at the target position. A correlation between a rotor position of the drive and an output voltage of a throttle valve angle transducer follows a characteristic.

Abstract: A fuel injection control device which is provided with an input terminal to which a first pulse signal for driving a liquid fuel injection valve is input and an output terminal from which the first pulse signal is output, and converts the first pulse signal which is input from the input terminal to a second pulse signal for driving a gaseous fuel injection valve, includes: a P-channel field-effect transistor interposed in a wiring which connects the input terminal and the output terminal; a switching control section which performs switching control between an ON state and an OFF state of the field-effect transistor; and a gate drive circuit which maintains the field-effect transistor in the ON state in a case where power supply to the switching control section is not performed.

Abstract: Methods and systems for estimating engine exhaust gas temperature and adjusting engine operation based on the engine exhaust gas temperature are disclosed. In one example, an offset value for a resistive heating element of an oxygen sensor is determined so that the resistive heating element may be a basis for providing accurate engine exhaust gas temperatures.

Abstract: Methods and systems are provided for adjusting a reference voltage for an intake manifold oxygen sensor based on ingestion of hydrocarbons from a fuel system canister and/or an engine crankcase. During conditions when purge or crankcase ventilation hydrocarbons are ingested in the intake aircharge, the intake oxygen sensor is transitioned from operating at a lower reference voltage to a higher reference voltage where the effects of the ingested hydrocarbons on the sensor output are nullified. An EGR dilution of the intake aircharge is estimated based on the output of the sensor at the higher reference voltage while an amount of hydrocarbons ingested is estimated based on a difference between sensor outputs at the higher and lower reference voltages.

Abstract: An internal combustion engine executes EGR and controls the air-fuel ratio based on a detected oxygen concentration in the exhaust. An electronic control unit controls the engine such that the detected value for the air-fuel ratio upstream from a front catalyst provided in an exhaust pipe reaches a value indicating a leaner air-fuel ratio when EGR is being executed than when not executed. Therefore, the controlled air-fuel ratio follows shifting of a window to the leaner side in response to execution of EGR, so that the air-fuel ratio is controlled more precisely in response to the execution of EGR.

Abstract: A golf club head, and a method of making the golf club head, with an improved striking surface. The grooves are formed in the strike surface with tight tolerances. The grooves may contain a plurality of portions, including a radiused or angled portion, a portion having substantially parallel walls, and a portion having a v-shape.

Abstract: A control system for an internal combustion engine that utilizes an oxygen sensor signal to control at least one fuel injector while generating a false oxygen sensor signal for input to an engine control unit.

Abstract: A control system for a turbo charged natural gas engine. A butterfly valve used for fuel control upstream of a carburetor provides non-linear flow response during opening and closing and a flow compensator compensates for the non-linear response. A throttle valve position sensor acts in association with a controller which compares the throttle valve position signal with a predetermined set point and thereby opens or closes the waste gate of the turbo charger which affects oxygen content in the exhaust. A compensator for a throttle valve used with electronic engine controllers is also provided.

Abstract: A method for determining the position of a component, that is able to be moved into at least two end positions with the aid of a drive, especially of a flap for controlling fluid flows in an internal combustion engine, includes the following steps: providing an electric signal that indicates the speed of motion of an element of the drive, determining a change in position of the component by the integration of the electric signal, and determining the absolute position of the component from the change in position.

Abstract: In a method and a device for operating an internal combustion engine, a first variable characterizing the air-mass flow to the internal combustion engine is determined, and a second variable characterizing the air-mass flow is determined. The second variable characterizing the air-mass flow is used to derive a third variable characterizing the air-mass flow, which is delayed in time with respect to the second variable characterizing the air-mass flow. A difference is formed between the second variable characterizing the air-mass flow and the third variable characterizing the air-mass flow. The first variable characterizing the air-mass flow is corrected by the difference.

Abstract: A control system for a turbo charged natural gas engine. A butterfly valve used for fuel control upstream of a carburetor provides non-linear flow response during opening and closing and a flow compensator compensates for the non-linear response. A throttle valve position sensor acts in association with a controller which compares the throttle valve position signal with a predetermined set point and thereby opens or closes the waste gate of the turbo charger which affects oxygen content in the exhaust. A compensator for a throttle valve used with electronic engine controllers is also provided.

Abstract: A system and method for controlling an engine involves providing a model for volumetric efficiency. The model recognizes that volumetric efficiency (VE) has stronger dependency on intake pressure than on exhaust pressure. The model allows tuning of the relative importance of intake pressure to exhaust pressure, specifically, by reducing the relative importance of the exhaust pressure to intake pressure in the composite volumetric efficiency load variable. The model provides for a calculation where the exhaust pressure term of the engine pressure ratio is de-rated through the use of an exponent less than one.

Abstract: The invention relates to an internal combustion engine which is provided with a manifold from which an intake tube extends to an intake of a cylinder of the internal combustion engine, with a gas inlet valve, disposed at the intake of the cylinder, an intermittent charge valve, disposed upstream of the gas inlet valve in the intake tube and releasing or closing the intake tube subject to a switching position of the intake tube, and in injection valve for metering fuel. The temporal position of the duration of injection of the fuel is adjusted subject to a point in time at which the switching position of the intermittent charge valve is changed. In this manner, it can be ensured that the air has a high velocity of flow during injection, thereby obtaining a good mixture preparation in a simple manner.

Abstract: The method for determining an air mass in a cylinder of an internal combustion engine with a supercharging device and with a device for variably controlling the valve overlap of the gas exchange valves is characterized by a reference characteristic curve for the air mass inside the cylinder that, according to the operating conditions, defines a linear correlation between the air mass inside the cylinder and the pressure inside the induction pipe, and when the induction pipe pressure exceeds the exhaust counter pressure, the value of the air mass from the reference characteristic curve is corrected with a value for the supercharging rate that is defined as the characteristic curve according to the operating conditions above the pressure inside the induction duct.

Abstract: A computer calculates an estimated cylinder-intake-air amount based on outputs from an airflow meter and a throttle position sensor, and then calculates a reference cylinder-intake-air amount based on an air-fuel ratio in an exhaust gas and fuel injection amount. An error of the estimated cylinder-intake-air amount is calculated by comparing the reference cylinder-intake-air amount with an estimated cylinder-intake-air amount base value. The error is low-pass filtered. The estimated cylinder-intake-air amount base value is corrected to obtain the final estimated cylinder-intake-air amount.

Abstract: An engine fuel injection control device including: means for detecting an amount of change per minimal time in intake pipe pressure of an engine as an intake pipe pressure change amount; means for performing an arithmetical operation of calculating an opening area of an orifice from a relationship between a mass flow rate of gas and the intake pipe pressure change amount in a process for the intake pipe pressure to increase after an intake valve of the engine is closed, the gas flowing through said orifice by a difference in pressure on both sides of the orifice when a throttle valve is regarded as the orifice; and means for estimating the opening area of the orifice as an opening area of the throttle valve to arithmetically operate an acceleration increase correction value of injection time based on the estimated opening area; and means for correcting an injection amount in acceleration of the engine using the arithmetically operated acceleration increase correction value.

Abstract: A target value of an engine load ratio is calculated. A target throttle opening required for making the actual engine load ratio equal to the target engine load ratio is calculated on the basis of an intake pipe pressure which is a pressure in the intake passage downstream of the throttle valve. It is judged whether the target throttle opening can be realized by a step motor. A final target throttle opening is set to a maximum or minimum throttle opening which can be realized by the step motor when it is judged that the calculated target throttle opening cannot be realized by the step motor. The step motor drives the throttle valve so that the actual throttle opening is made equal to the final target throttle opening, and the intake pipe pressure is estimated on the basis of the final target throttle opening.

Abstract: A target value of an engine load ratio is calculated. A target throttle opening required for making the actual engine load ratio equal to the target engine load ratio is calculated on the basis of an intake pipe pressure which is a pressure in the intake passage downstream of the throttle valve. A convergent throttle opening, which is a throttle opening to which the actual throttle opening converges assuming that the target intake air amount is kept at the calculated target intake air amount, is calculated. A final target throttle opening is set to the target throttle opening when the engine transient operation is in process, and to the convergent throttle opening when the engine steady operation is in process. Then, the throttle valve is driven so that the actual throttle opening is made equal to the final target throttle valve.

Abstract: A system and method for controlling a plurality of control-coupled charge-handling actuators for an internal combustion engine has a multivariable controller responsive to a plurality of engine parameter inputs and effective to provide a plurality of position control signals to the charge handling actuators. Coupling effects of the charge-handling actuator are effectively addressed by the present multivariable control leading to substantial improvements in engine emissions particularly during transient operating conditions.

Abstract: A pressure sensor device of an internal combustion engine includes: a pressure sensor detecting a pressure in an intake pipe of an internal combustion engine, a pressure sensor failure determination device determining a failure of the pressure sensor, an idle determination device detecting that an opening of a throttle adjusting an air quantity supplied to the internal combustion engine is in an idle position, and a pressure sensor output value control device limiting an output value from the pressure sensor for use in a fuel injection quantity control of the internal combustion engine to be not more than a predetermined value when the throttle opening is determined by the idle determination device to be in the idle position and when the pressure sensor is not determined as being in failure by the pressure sensor failure determination device. This pressure sensor device prevents the over-rich of fuel injection quantity.

Abstract: A device for estimating the amount of intake air of an internal combustion engine comprising intake pipe pressure calculation means for calculating an intake pipe pressure, at this time, downstream of the throttle valve, and intake air amount calculation means for calculating the amount of intake air, at this time, based on the intake pipe pressure at this time calculated by said intake pipe pressure calculation means, is provided. The intake pipe pressure calculation means calculates the intake pipe pressure at this time by using the intake pipe pressure calculated at the last time and the amount of air passing through the throttle valve at the last time calculated by means for calculating the amount of air passing through the throttle valve.

Abstract: The invention relates to an internal combustion engine comprising a fuel injector (2) for each cylinder; a fuel injection control unit (4) for controlling fuel injection quantity and a piston (5) in each cylinder whose compression action causes a mixture of air and fuel to be ignited. The engine is further provided with inlet and outlet valves (6, 7) and various sensors (12-16) for measuring various engine operating parameters. During compression ignition mode, the control unit (4) is arranged to select a ?-value from a map stored in the control unit, which value is a function of engine load and engine speed, and to compare the actual ?-value with the selected ?-value; whereby the control unit is arranged to adjust the intake manifold pressure as a function of the difference between the said ?-values in order to obtain the selected ?-value. The invention further relates to a method for operating the engine and a computer readable storage device (4).

Abstract: A system for balancing first and second work outputs between first and second cylinder banks of an engine includes a first intake camshaft associated the first cylinder bank and a first fuel injector associated with the first cylinder bank. A controller trims a pulse-width of the first fuel injector until first and second A/F ratios of respective exhaust of the first and second cylinder banks are equivalent. The controller adjusts timing of the first intake camshaft to effect air flow into the first cylinder bank and trims the pulse-width to maintain equivalency of the first and second A/F ratios.

Abstract: The invention relates to a method and an arrangement for operating an internal combustion engine wherein at least one control quantity of the engine is influenced in dependence upon a signal representing the fresh air charge. The throttle flap angle and the intake manifold pressure are determined and a respective signal is formed on the basis of the throttle flap angle and on the basis of the intake manifold pressure. The charge signal, which is formed on the basis of the throttle flap angle, is adapted to the signal, which is formed on the basis of the intake manifold pressure sensor, with the aid of at least one corrective factor.

Abstract: It is checked whether or not a supercharged pressure Pb becomes equal to or greater than a predetermined value P0 to judge whether or not a mechanism for adjusting the supercharged pressure is failed. When it is judged that the mechanism for adjusting the supercharged pressure is not failed, the fuel injection quantity Tp of normal time is computed based upon the engine operation condition. When it is judged that the mechanism for adjusting the supercharged pressure is failed, on the other hand, the fuel injection quantity Tp of failed time is computed, which is smaller than the fuel injection quantity of normal time. The fuel injection is then controlled based upon either the computed fuel injection quantity Tp of normal time or the computed fuel injection quantity Tp of failed time.

Abstract: One embodiment of the present invention includes sensing speed or an internal combustion engine that includes a manifold coupled to an air pathway and a gaseous fuel line, sensing manifold pressure, and sensing manifold temperature. Air mass flow rate is determined as a function of the sensed engine spaced, manifold pressure, and manifold temperature. Fuel mass flow rate in the fuel line is sensed and fuel is controlled through the fuel line in accordance with the air mass flow rate and the fuel mass flow rate.

Abstract: An engine includes an electronic controller which samples the pressure in the induction system once per rotation of the crankshaft. The controller is configured to determine the minimum voltage signal output by the pressure sensor. The controller then uses the minimum pressure sensed by the pressure sensor to control the fuel injection of the engine. The controller may include two and/or three dimensional maps for predicting the appropriate timing for sampling the pressure sensor. The engine also includes a smoothing system so as to provide for more accurate sampling of the pressure within the induction system.

Abstract: An internal combustion engine is simulated as a control model that covers from a fuel injection point to an air-fuel ratio detection point. A response time constant of the control model is calculated as a continuous function of the amount of intake air, and a control gain of the control model is calculated as a continuous function of the response time constant. Control parameters of the control model are calculated using a calculation interval, the response time constant, an attenuation coefficient and the control gain. Thus, the control parameters are varied continuously in response to changes in the intake air amount. The air-fuel correction coefficient is calculated using the control parameters a0, a1, a2, b1 and b2 as well as a deviation of an actual air-fuel ratio from a target air-fuel ratio. The amount of fuel supplied to the engine is calculated using the air-fuel ratio correction coefficient.

Abstract: An engine includes an electronic controller which samples the pressure in the induction system once per rotation of the crankshaft. The controller is configured to determine the minimum voltage signal output by the pressure sensor. The controller then uses the minimum pressure sensed by the pressure sensor to control the fuel injection of the engine. The controller may include two and/or three dimensional maps for predicting the appropriate timing for sampling the pressure sensor. Optionally, the controller may include a bottom hold device for holding a minimum value of the signal output from the pressure sensor, thus corresponding to the minimum pressure sensed by the pressure sensor.

Abstract: A continuous flow fuel system includes an oxygen sensor for analyzing the exhaust gases of an engine. The output from the oxygen sensor, representing the oxygen content in the exhaust gases, is transmitted to an electronic control module, which in turn controls the output of a fuel pump. The output of the fuel pump provides fuel to maintain a desired fuel/air ratio. The desired fuel/air ratio may be selected by a user of the engine or it may be predetermined and factory-set.

Abstract: A fuel injection amount controller for engines capable of decreasing the shocks caused by the correction of increasing or decreasing the amount of fuel at the time of changing over the operation mode. The fuel injection amount controller includes an operation condition detector for detecting the operation conditions of an engine inclusive of an intake pipe pressure and a crank angle. An air-to-fuel ratio controller controls the air-to-fuel ratio of the engine to a ratio more lean than stoichiometric when operation conditions represent a predetermined operation condition. A pressure deviation detector calculates a pressure deviation in the intake pipe pressure within a predetermined period of time or between predetermined crank angles. A fuel amount correction device injects the fuel in an amount corresponding to the pressure deviation when the deviation is not smaller than a predetermined value.

Abstract: Engine (60) has manifold (62) and includes an air pathway (20) and a fuel line (30) coupled to the manifold (62) for supplying a fuel charge. Fuel line (30) has a controllable valve (40) for regulating fuel flow and a first sensor (38) providing a fuel signal corresponding to mass flow rate of fuel through the fuel line. A second sensor (65) provides a speed signal corresponding to rotational speed of the engine. A third sensor (63) provides a temperature signal corresponding to temperature within the manifold. A fourth sensor (64) provides a pressure signal corresponding to pressure within the manifold. A fifth sensor (76) provides an exhaust signal corresponding to air/fuel ratio for combusted air and fuel in the exhaust pathway. A controller (80) responsive to the controllable valve (40) and sensors (38), (63), (64), (65), and (76) determines an air signal corresponding to the mass flow rate of air through the air pathway (20) as a function of the speed signal, temperature signal, and pressure signal.

Abstract: Engine (60) has manifold (62) and includes an air pathway (20) and a fuel line (30) coupled to the manifold (62) for supplying a fuel charge. Fuel line (30) has a controllable valve (40) for regulating fuel flow and a first sensor (38) providing a fuel signal corresponding to mass flow rate of fuel through the fuel line. A second sensor (65) provides a speed signal corresponding to rotational speed of the engine. A third sensor (63) provides a temperature signal corresponding to temperature within the manifold. A fourth sensor (64) provides a pressure signal corresponding to pressure within the manifold. A fifth sensor (76) provides an exhaust signal corresponding to air/fuel ratio for combusted air and fuel in the exhaust pathway. A controller (80) responsive to the controllable valve (40) and sensors (38), (63), (64), (65), and (76) determines an air signal corresponding to the mass flow rate of air through the air pathway (20) as a function of the speed signal, temperature signal, and pressure signal.

Abstract: A cylinder-by-cylinder air-fuel ratio-estimating system for an internal combustion engine includes an air-fuel ratio sensor arranged in the exhaust system of the engine, at a confluent portion of the exhaust system. The air-fuel ratio of a mixture supplied to each of the cylinders of the engine is estimated based on an output from the air-fuel ratio sensor, by using an observer for observing the internal operative state of the exhaust system based on a model representative of the behavior of the exhaust system. A gain for use in the estimation of the air-fuel ratio of the mixture supplied to each of the cylinders is estimated by the observer according to operating conditions of the engine.

Abstract: A system for controlling fuel metering for an internal combustion engine having a feedback system which has a controller for calculating a feedback correction coefficient, using an adaptive control law to correct a quantity of fuel injection such that a detected air/fuel ratio is brought to a desired air/fuel ratio. In the system, it is discriminated whether the feedback correction coefficient and the detected air/fuel ratio are in phase, and the feedback system is instable when they are discriminated to be in phase. Since the coefficient acts to correct the deviation of the detected air/fuel ratio from the desired air/fuel ratio, they are normally in antiphase. It is thus possible to find the system instable, by discriminating whether they are in phase or not.

Abstract: A fuel metering control system for an internal combustion engine, having a feedback loop. In the system, the quantity of fuel injection (Tim) to be supplied to the engine (plant) is determined outside of the feedback loop. A first feedback correction coefficient (KSTR) is calculated using an adaptive law, while a second feedback correction coefficient (KLAF), whose control response is inferior to that of the first feedback correction coefficient, is calculated using a PID control law. The feedback correction coefficients are calculated such that the plant output (air/fuel ratio) is brought to a desired value (desired air/fuel ratio). The coefficients are calculated at least in parallel and either of them is selected to be multiplied by the quantity of fuel injection (Ti).

Abstract: An oxygen concentration detecting apparatus precisely and easily performs diagnosis of a limit current type oxygen sensor. The limit current type oxygen sensor has an oxygen concentration detecting element for outputting limit current proportional to the oxygen concentration and a heater for heating the detecting element. A CPU of a microcomputer controls energization of the heater to activate the oxygen sensor. The CPU calculates element resistance based on the voltage applied to the oxygen sensor and the current detected in the sensor. In a sensor diagnosis routine, the CPU determines whether preconditions for the diagnosis have been met. If all the preconditions have been met, the CPU executes the diagnosis. That is, the CPU determines whether the element resistance is within a predetermined range. If it is below the range, the CPU determines that the sensor has high element temperature abnormality.

Abstract: An apparatus for controlling the air-fuel ratio of an internal combustion engine has an air-fuel ratio sensor for detecting an air-fuel ratio of the internal combustion engine, and a fuel supply control device for controlling an amount of fuel supplied to the internal combustion engine based on the air-fuel ratio detected by the air-fuel ratio sensor. The fuel supply control device has a feedback control system for controlling the amount of fuel supplied to the internal combustion engine through a feedback control loop according to a sliding mode control process in order to equalize the detected air-fuel ratio with a target air-fuel ratio.

Abstract: An air/fuel ratio feedback control system with the adaptive controller. The adaptive controller has a system parameter estimator which identifies system parameters such that the error between the desired value and the controlled variable outputted from the plant decreases to zero. In the system, a basic fuel injection amount is determined at a feedforward system. The adaptive controller is placed outside of the basic fuel injection amount determining system and receives the desired value (air/fuel ratio) and the controlled value (detected air/fuel ratio) using the system parameters etc. The calculated feedback coefficient is multiplied to the basic fuel injection amount to determine a final injection amount to be supplied to the plant (engine). Variables necessary for the system parameter calculation are limited their change of range so as to make the controller to be realized on a low performance computer with a small word length.

Abstract: In an internal combustion engine in which the valve operating characteristic for intake valves can be switched, and the air-fuel ratio can be switched between a relatively lean level and a relatively rich level, the air-fuel ratio is switched in accordance with a change in engine operating condition.

Abstract: A fuel control system for an engine, and particularly one that employs a gaseous fuel and which controls the air-fuel ratio by a feedback control system. The feedback control system is adjusted by a corrective factor that is determined by engine running conditions so as to obtain better control over the desired fuel-air mixture.

Abstract: A fuel injection mount control system for an internal combustion engine includes an ECU which calculates a first amount of fuel directly drawn into each combustion chamber out of an amount of fuel injected into the intake passage via a corresponding fuel injection valve, a second amount of fuel carried off fuel adhering to the wall surface of the intake passage into the combustion chamber, and an amount of fuel to be injected into the intake passage, based on the first fuel amount and the second fuel amount, calculates an air-fuel ratio correction amount, based on an output form an air-fuel ratio sensor arranged in the exhaust system, and corrects the amount of fuel to be injected into the intake passage by the air-fuel ratio correction amount. Further, the ECU corrects the second fuel amount, based on the air-fuel ratio correction amount.

Abstract: Lean burn, exhaust gas recirculating internal combustion engine system (10) and process of operation wherein a motor driven valve (16) governs tapping of exhaust gas via a conduit (11) to the high pressure side of a throttle (14) in an air intake region of the engine with control of the valve and lean burn to maintain a) lean operation with high exhaust dilution at light engine loads, b) high exhaust dilution and high overall dilution at medium to high engine loads and c) smooth transition between a) and b).

Abstract: In a fuel vapor purge mechanism, the fuel vapor generated from a fuel tank and stored in a canister undergoes flow volume control with a purge solenoid valve while being introduced to an intake system of the engine via a purge passageway. Meanwhile, in an air/fuel ratio feedback control system, by means of a linear air/fuel ratio sensor mounted on an exhaust system of the engine, the air/fuel ratio of air-fuel mixture of fuel and intake air including the fuel vapor. If a change amount of a purge ratio the fuel vapor goes above a determined value, there is compensation of the air/fuel ratio compensation coefficient FAF concerned with the feedback control based on the change ratio.

Abstract: A control system according to one aspect calculates a ratio of an actual amount of fuel supplied to the combustion chamber to the desired amount of fuel to be supplied to the combustion chamber, by taking into account at least an amount of evaporative fuel supplied to the combustion chamber, and sets the rate of change of the air-fuel ratio correction coefficient based on this ratio of the actual amount to the desired amount. A control system according to another aspect of the invention calculates an injected fuel ratio of an amount of fuel injected to an amount of total fuel to be supplied to the combustion chamber, and controls the ignition timing based on the injected fuel ratio and depending on operating conditions of the engine.