Abstract: A basic injection quantity is determined by engine speed and intake passage pressure. The pressure is estimated from engine speed and throttle position, and changing rate of the estimated pressure is calculated. A correcting quantity is obtained from the changing rate of the estimated pressure. The basic injection quantity is corrected with the correcting quantity.

Abstract: There is disclosed a system for controlling air-fuel ratio of a combustion mixture fed to an internal combustion engine. The system comprises an oxygen sensor disposed in an exhaust system of the engine, the oxygen sensor exhibiting a sudden characteristic change when exposed to an exhaust gas produced by a combustible mixture of stoichiometic air-fuel ratio, the oxygen sensor issuing a signal representative of the oxygen concentration in the exhaust gas; first means for substantially linearizing the signal to produce a semi-linearized signal; and second means for controlling the amount of fuel fed to the engine in accordance with the semi-linearized signal.

Abstract: A fuel controller for an internal combustion engine has a Karman vortex air flow sensor for sensing the air flow rate into the air intake pipe of the engine and producing an electrical output signal having a frequency which is proportional to the air flow rate. A load sensor determines the air flow rate into an air intake pipe based on the output of the air flow sensor. A determining mechanism determines whether the output of the air flow sensor is reliable. A calculator calculates the actual air intake rate into the engine according to a first formula which employs the most recent output of the load sensor when the determining mechanism determines that the output of the air flow sensor is reliable, and it calculates the actual air intake rate according to a second formula which ignores the most recent output of the air flow sensor when the determining mechanism determines that the output of the air flow sensor is not reliable.

Abstract: A fuel injection system includes a valve for supplying fuel to an internal combustion engine; a device for measuring the quantity of air passing through an air intake passageway in both forward and backward directions; a device for detecting the number of revolution of the engine; a device for detecting conditions of the engine; a limiting device, which is used when an output therefrom produces a time width of a pulse to be imparted to the fuel injection valve, and which limits variables related to the atmospheric pressure including a measured value of the air quantity limited by the number of engine revolutions; and an atmospheric pressure conformed corrective value computing device.

Abstract: An apparatus for controlling the operation of an engine based on the pressure in an intake manifold. If a change in the pressure in the intake manifold is equal to or less than a predetermined value during a predetermined period within the period from the time when a voltage source is turned on to the time when a starter is turned on, the pressure in the intake manifold is detected and stored. If the engine is not in the start mode, the rate of fuel supply is increased based on an atmospheric pressure detection value. Based on the comparison between the atmospheric pressure value and a predetermined value, a passage for bypassing a throttle valve is opened and closed to control the idling of the engine.

Abstract: A method for controlling fuel injection rate in internal combustion engine in accordance with the intake pressure and the engine speed. The method has the steps of determining the intake pressure using, as a variable, the period of time after a change in the throttle opening, and computing a basic fuel injection period on the basis of the thus computed intake pressure and the engine speed. The fuel injection is conducted by a system in accordance with this method. The system determines the intake pressure in the steady state of engine operation in accordance with the throttle opening and the fuel injection rate, effects a correction on the thus determined intake pressure so as to take into account a delay in response of the intake pressure to the transient period, and determines the basic fuel injection period on the basis of the corrected intake pressure and the engine speed.

Abstract: An air/fuel ratio control system detects an air/fuel ratio indicative control parameter out of required precision range for initiating a control characteristics derivation process. The control characteristics derivation process is performed by varying constant consisting an air/fuel ratio dependent fuel delivery amount correction coefficient in trial basis to monitor fluctuation range of the correction coefficient. Based on the trial basis processings, the value of the constant is determined so as to compensate the precision level lowered in monitoring the air/fuel ratio.

Abstract: A fuel control apparatus for an internal combustion engine comprises an crank angle sensor producing a crank angle signal at a predetermined crank angle in the engine, an intake air quantity detector for detecting the quantity of intake air sucked in the engine, an injector for injecting fuel to an engine cylinder, and a control means for actuating the injector at a driving time in response to the quantity of intake air and at a timing determined by the crank angle signal, wherein a period calculating means calculates the next period on the basis of the previous period and the present period in the crank angle signal and an injection-initiating time control means controls a time to actuate the injector in accordance with the next period of the crank angle signal.

Abstract: An air-fuel ratio control system for an engine, has an O.sub.2 -sensor, an actuator for controlling air-fuel ratio of mixture, and a feedback control system responsive to the output of the O.sub.2 -sensor for operating the actuator thereby controlling the air-fuel ratio. The feedback control system includes a peak-to-peak voltage producing circuit for producing an upper peak value signal and a lower peak value signal, a reference value circuit responsive to the upper and lower peak value signals for providing a reference value, a comparator for comparing the output of the O.sub.2 -sensor with the reference value and for producing an error signal, and a driving circuit responsive to the error signal for operating the actuator. A limiter is provided between the O.sub.2 -sensor and the peak-to-peak voltage producing circuit for cutting a part of the voltage exceeding a predetermined level.

Abstract: The amount of air being inducted into the cylinders of an internal combustion engine is detected and a signal indicative thereof is sampled at a predetermined intervals. The difference between two sampled values is used with the time required for a single induction phase to be carried out, to predict the total amount of air which will be inducted into each cylinder. Utilizing this approximation the amount of fuel which should be injected or otherwise supplied to the engine can be accurately determined and thus enable accurate real-time cycle to cycle A/F control.

Abstract: A fuel feed quantity control system of the so-called L-Jetronic system is described. The system is equipped with a Karman vortex air-flow sensor, at least one injector for feeding a fuel into an internal combustion engine, a controller for controlling the quantity of the fuel, which is to be injected, on the basis of intake air flow rate information from the air-flow sensor, and at least one operation parameter sensor. The controller also includes at least one additional control unit which serves to correct the quantity of the fuel, which is to be fed into the engine, in accordance with at least one operation parameter from the operation parameter sensor and frequency information outputted from the air-flow sensor. The quantity of the fuel, which has been determined based on an output from the air-flow sensor, is corrected by the controller in accordance with changes in kinematic viscosity of the atmospheric air.

Abstract: An arrangement for the identification of the mass air stream supplied to the cylinders of an internal combustion engine. A controlled unit serves the purpose of controlling a prescribed relationship between mass air stream and fuel quantity, whereby a correction quantity (.tau.) from a performance characteristics memory is deposited dependent on at least one operating parameter. In accordance with the invention, this thereby involves a correction quantity which takes the dynamic behavior of the intake system, particularly its storage capacity, into consideration. Accordingly, the control unit identifies a corrected mass air stream which is smaller or, respectively, greater than the measured mass air stream by the sub-stream filling the storage or, respectively, flowing off from the storage.

Abstract: A control system for a fuel injection system has a mass air flow meter for producing an air flow signal dependent on quantity of induced air, and an acceleration detector for detecting acceleration of the engine and for producing an acceleration signal. In response to the acceleration signal, the value of the air flow signal is reduced for a time. An actuator of the fuel injection system is operated in accordance with the reduced air flow signal.

Abstract: A setting device of basic fuel injection amount for an internal combustion engine in an operating region of acceleration comparing a detected amount of intake airflow with a retrieved amount of intake airflow stored with the area of opening of a throttle valve and the engine velocity used as parameter, and when the detected amount is less than the retrieved amount, modifying the detected amount on the basis of the change ratio of opening area in the throttle valve, the engine load and the engine velocity, thereby modifying the detected amount so that it is close to the amount required by the engine.

Abstract: A system for correction of the fuel injection time control upon variation in altitude, for a heat engine having an electronic fuel injection system, and having means for substantially detecting the value of the external atmospheric pressure and the consequently correcting the value of induction air pressure utilized by a central processing unit of the injection system for calculating the injection time.

Abstract: A system for correcting for atmospheric pressure without using an atmospheric pressure sensor. A single pressure sensor measures air pressure in the intake manifold of a fuel injected engine. A control unit controls the fuel amount and injection timing in accordance with various engine parameters. The intake pressure at a predetermined time is estimated as being indicative of atmospheric pressure. This intake pressure may be further corrected to provide a better estimate. When the engine operates at a low speed and high load, this pressure data is also indicative of atmospheric pressure. The amount of fuel to be injected and the ignition timing can be controlled using this updated atmospheric data. This provides better operation of the system.

Abstract: A system for controlling the operation of an internal combustion engine on the basis of air/fuel ratios and engine loads. A flow rate of intake air sucked into the engine and the cycle of engine revolutions are detected to determine an average flow rate of intake air, which is then used in cooperation with a compression ratio and an engine displacement to determine a net flow rate of intake air or the charging efficiency of the engine. This parameter represents a precise engine load and is used to regulate fuel injected into the engine. As a result, engine operations may be optimally controlled even during transitional operating states of the engine.

Abstract: A fuel supply control apparatus for an internal combustion engine comprises a detecting means for detecting the increment of air intake quantity for the internal combustion engine and a sensor for detecting temperature of the cooling water of the internal combustion engine so that the fuel supply quantity is increased according to the temperature of cooling water when the increment of air intake quantity is detected, thereby enabling rapid increment of fuel supply quantity according to the increment of the revolution of the engine and compensation of fuel supply loss, which is caused by adhesion of liquefying fuel inside the air intake pipe and the like, according to the temperature of cooling water.

Abstract: Disclosed in an internal combustion engine control system for controlling at least one of the quantity of intake air and quantity of fuel supply, and to an internal combustion engine control system for controlling the air-fuel ratio of the mixture. The invention particularly relates to the control of the engine at a transition of operating condition. The former control system detects the change in one of the quantity of intake air and quantity of fuel supply and compensates the other, thereby controlling the engine by anticipation at a transition of control condition.

Abstract: A fuel supply control apparatus for an internal combustion engine comprises a detecting means for detecting the decrement of air intake quantity for the internal combustion engine and a sensor for detecting temperature of the cooling water of the internal combustion engine so that the fuel supply quantity is decreased according to the temperature of cooling water when the decrement of air intake quantity is detected, thereby enabling rapid decrement of fuel supply quantity according to the decrement of the revolution of the engine and compensation of fuel supply loss, which is caused by adhesion of liquefying fuel inside the air intake pipe and the like, according to the temperature of cooling water.

Abstract: An internal combustion engine is provided with a fuel injection valve. The fuel injection valve is actuated so that fuel injected therefrom reaches the combustion chamber in the latter half of the intake stroke, thereby accomplishing stratified charge. The timing at which blow-back of intake gas occurs is detected and the timing for terminating fuel injection is advanced as the timing at which blow-back of intake gas occurs becomes earlier.

Abstract: A fuel injection control device for an internal combustion engine comprising a throttle position sensor, a pressure sensor or a potentiometer for detecting a flow of the intake air in units of a certain physical quantity, and a third detecting device for detecting whether the engine is operating in a steady state. The device further includes a device for estimating the load of the engine from the output of the throttle position sensor and a learning device for correcting the estimation provided by the estimating device based on the output of the air flow sensor when the engine is operating in a steady state, so that the load estimation value can be corrected in accordance with the actual air flow. The amount of fuel to be injected is calculated in response to the most recently corrected load estimation value obtained from the output of the throttle position sensor.

Abstract: An engine control system which controls ignition timing for, and fuel supply to, an engine by scanning a map by using as parameters a first item of data representing the number of revolutions of the engine and a second item of data representing engine load. The engine control system includes filter means for providing a third item of data by suppressing the rate of change of the second item of data. The third item of data is used in place of the second item of data for scanning the map only when the engine is in a predetermined range of operating conditions in which the rate of change of a manipulated variable of a throttle valve, the number of revolutions of the engine and the rate of change of the engine load are all less than respective predetermined values.

Abstract: A method and apparatus for electronically controlling injection of fuel into an engine selectively uses fuel injection control based on an intake air flow rate sensing system (e.g. L-J system fuel injection control) and fuel injection control based on a speed density system (e.g. D-J system fuel injection control), this depending upon the amount of intake air. In an engine operating region where a control relationship between these two forms of fuel injection control is constant, e.g. in an operating region where the amount of intake air is low, the relationship is stored. In a region of high air intake, where the relationship no longer holds, the amount of fuel injection in the speed density system is corrected on the basis of the aforementioned relationship.

Abstract: A fuel supply control system for an internal combustion engine which is capable of precisely controlling the amount of fuel to be supplied to an engine so as to provide a predetermined air/fuel ratio irrespective of the provision of an EGR system or the amount of EGR in the case of EGR control. Fuel is supplied to an engine by fuel injection valves, and a part of exhaust gas discharged from the engine is adjustably recirculated to a location downstream of a throttle valve in an intake pipe. In a memory that is stored data detemining the amounts of fuel to be supplied to the engine in the absence of the exhaust gas recirculation corresponding to the respective engine operating conditions which are determined by the manifold pressure of the intake gases at the downstream side of the throttle valve detected by a pressure detector and the engine RPM detected by an engine RPM detector, and which are classified in a two dimensional manner.

Abstract: Compensation of an output from an oxygen concentration sensor of an air/fuel ratio control apparatus for an internal combustion engine is executed during engine warm-up, to correct for an erroneous component in the oxygen concentration sensor output data caused by incomplete combustion during warm-up. The degree of compensation applied is determined by the engine operating temperature, as represented by the cooling water temperature. Excessive richness of the air/fuel ratio of the mixture supplied to the engine during warm-up is thereby eliminated.

Abstract: A non-linear position transducer for detecting the position of a valve controlling the rate of flow of air inducted to the cylinders of a heat engine comprising a first means for detecting the position of this valve, and second means coupled to the first means and operable to provide an electrical output signal in non-linear relationship with the position of the valve, and in which these second means comprise an electrical circuit having only passive components.

Abstract: A fuel control apparatus for a fuel injection system of an internal combustion engine has an air flow sensor for sensing the air flow rate into the air intake pipe of the engine and producing an electrical output having a frequency which is proportional to the air flow rate, and a crank angle sensor for producing an electrical output pulse each time the crankshaft of the engine is at a prescribed crank angle. A load detector detects the number of output pulses from the air flow sensor between consecutive output pulses of the crank angle sensor, and an air flow rate calculator calculates the actual intake air flow rate into the cylinders of the engine based on the output of the load detector. A controller controls the supply of fuel to fuel injectors for the engine based on the output of the calculator. The load detector includes a frequency divider which performs frequency division of the output from the air flow sensor when the load exceeds a prescribed level.

Abstract: A fuel injection control system for an internal combustion engine having means for limiting a fuel amount to be supplied to the engine according to an output of an air flow sensor to a predetermined upper limit value, and means for correcting the intake air flow rate by the output of the air flow sensor when the opening of an intake air throttle valve is opened at a predetermined value, thereby limiting the output of the sensor to the predetermined upper limit value in case that the output of the sensor increases larger than the actual value and correcting the air density if different from a reference by the correcting means.

Abstract: In an electronic fuel injection control device for an internal combustion engine, an A-D converter is provided to convert an analogue signal indicative of a physical value such as an intake manifold negative pressure or an amount of suction air to a digital value, and a computer is programmed to calculate an average of a plurality of the digital values successively converted during one rotation of the engine, to determine whether or not a difference between the preceding average of the digital signals and the following average of the digital signals is larger than a predetermined value indicative of a transient operation of the engine, if so determine a first optimum physical value based on an average of at least two digital values most newly converted during one rotation of the engine, and if not determine a second optimum physical value based on the average of the digital values, and to determine an optimum fuel injection time based on one of the first and second optimum physical values and in relation to r

Abstract: Interpreted intake-manifold vacuum and engine speed are used to produce an electrical output signal that reflects throttle position. Since the device has no mechanical tie to the throttle, there is none of the hysteresis or mechanical wear that are characteristic of conventional throttle-position sensors. The device comprises a tachometer circuit which is modulated by the signal from a differential-pressure transducer, connected to track the instantaneous pressure drop across the engine throttle. The tachometer output controls the duty cycle of a pulse generator which, in turn, drives an output transistor; a reference potential is applied across the load resistor and emitter of this output transistor, and the output signal is obtained as a d-c control signal, upon filtering the signal from the collector of the output transducer. The transfer function of the device yields maximum output when there is little or no intake vacuum, e.g.

Abstract: A method of controlling fuel supply to an internal combustion engine, wherein a quantity of fuel for supply to the engine is determined by correcting a basic value of the quantity of fuel determined as a function of at least one operating parameter of the engine by correction values dependent upon operating conditions of the engine, and the determined quantity of fuel is supplied to the engine. A value of at least one predetermined operating parameter of the engine is detected. A single voltage creating means is adjusted to set an output voltage therefrom to a desired value. Predetermined one of the correction values has a value thereof set as a function of the output voltage from the voltage creating means and dependent upon the value of the at least one predetermined operating parameter of the engine.

Abstract: The air-fuel ratio of an air-fuel mixture supplied to an internal combustion engine is determined on the basis of a smoothed amount of intake air and a smoothed throttle opening. The smoothed amount of intake air is reflected by a predetermined ratio of a former amount of intake air to the newest amount of intake air. The smoothed throttle opening is reflected by a ratio of a former throttle opening to the newest throttle opening substantially identical to said predetermined ratio.

Abstract: An ignition timing control system mounted at an internal combustion engine, particularly, a non-surge tank type engine, is constituted by a crank angle sensor, an engine rotational speed sensor, an intake pipe air pressure sensor, and a microcomputer. In the microcomputer, an intake pipe air pressure correction unit for calculating a correction term and for obtaining a corrected intake pipe air pressure value, an optimal advanced angle calculation unit for obtaining an optimal advanced crank angle based on a control map having an optimal advanced angle between the corrected intake pipe air pressure and the engine rotational speed, and an ignition command unit for commanding an ON/OFF timing of a primary current of an ignition coil, are provided.

Abstract: A fuel supply control apparatus for an internal combustion engine, which, when an air quantity detected at a predetermined crank angle of the internal combustion engine is represented by Qa and the (n-1)th air intake quantity and the next (n)th air intake quantity of the internal combustion engine at the predetermined crank angles thereof by Qe(n-1) and Qe(n) respectively, judges the optimum fuel supply quantity of the internal combustion engine by an equation: Qe(n)=K.multidot.Qe(n-1)+(1-K).multidot.Qa with filtering using the filter constant K, and which varies the filter constant K corresponding to an operating condition of the internal combustion engine, for example reduces K during idling, so that the fuel supply quantity can be controlled most suitably during idling and loaded operation.

Abstract: A fuel control apparatus for an engine has a temperature sensor for detecting the temperature of the intake air to the engine, and is constructed to correct the upper limit value of the intake air amount preset in response to the operating characteristic of the engine in the operating range of the engine which does not exhibit the true value of the intake air amount by the detected output of the air flow sensor due to the reverse-flow effect of the intake air of the engine by the detected temperature by the temperature sensor.

Abstract: The outputs generated by the throttle position sensor and the pressure responsive type air flow sensor (or alternatively a flap type air flow meter or the like) are used to generate correction factors which when combined permit the correction of the air flow sensor output for a short period following the initiation of a demand for engine acceleration to obviate the discrepency between the actual and indicated air flows and thus improve the real-time control of the air-fuel ratio (A/F) of the mixture and the level of emission control and performance of the engine.

Abstract: Acceleration enrichment for an internal combustion engine is provided in response to the rate of change of an unfiltered measurement of throttle position at the lower engine speeds and in response to the rate of change of a filtered measurement of throttle position at the higher engine speeds.

Abstract: A signal generator provides a non-linear fuel-control output signal, in response to an analog input-voltage signal which is linearly related to throttle setting. A multi-step switch divides into equal increments the full range of possible throttle-setting signals, and, in conjunction with a resistor network, provides a stepped output, the progression of which is a non-linear function of throttle setting. A dither circuit produces an oscillating sawtooth voltage of amplitude scaled to a one-step increment, and addition of this voltage to the throttle-setting voltage is effective to produce a smooth and effectively continuous non-linear output of the resistor network. A smoothing circuit at output of the resistor network yields a d-c output which is non-linearly related to the throttle setting.

Abstract: A fuel injection control system intended to correct for return blow. First, the sensed throttle valve opening is corrected according to the engine'rotation rate to provide a correction factor. Then this correction factor is combined with a sensed air-flow signal and an air temperature signal to provide a corrected air-flow amount.

Abstract: A fuel injector control apparatus wherein a total opening of a throttle valve and a bypass value are calculated in order to correct return blow through a flow sensor.

Abstract: A fuel control apparatus for an engine has an atmospheric pressure sensor for detecting the atmospheric pressure in the vicinity of the engine, and is constructed to correct the upper limit value of the intaken air amount preset in response to the operating characteristic of the engine in the operating range of the engine which does not exhibit the true value of the intaken air amount by the detected output of the air flow sensor due to the reverse-flow effect of the intaken air of the engine.

Abstract: In an apparatus for controlling an engine, as an air flow sensor for measuring intake air flow quantity, a heater resistor having temperature-resistance characteristic and a temperature sensitive resistor for sensing air temperature are provided in an intake passage, and heating electric power is supplied to the heater resistor in response to a start signal generated periodically. The heating electric power is cut off when the temperature of the heater resistor is raised to a specified reference temperature predetermined in accordance with the air temperature, so that an output signal indicative of the time width in which the heating electric power is supplied is applied to an electronic control unit to measure air flow quantity therefrom.

Abstract: The invention relates to an electronically controlled fuel injection system for an internal combustion engine wherein all dependency on the supply voltage for the electro-hydraulic components is compensated for and/or the pressure-regulator characteristic dependent upon the pumped quantity is compensated for. With respect to the dependency of the electric fuel pump on the supply voltage, this is accomplished by means of a correction factor for the basic injection signal. Below a specific voltage value which corresponds to the voltage required for maintaining the system pressure, this correction factor becomes progressively larger. The pressure regulator characteristic dependent upon the quantity of fuel pumped is taken into account in the correction in a corresponding manner.

Abstract: An engine control apparatus has an air flow rate measuring device for measuring an intake air flow rate. A temperature sensing element having a temperature characteristic and constituting the device is arranged in an intake pipe. The device generates an output pulse signal having a pulse width T corresponding to the intake air flow rate. An engine control unit has the one-dimensional map for storing the relationship between the engine speed N and the pulse width to of the signal corresponding to the air flow rate. This data to is read out from the one-dimensional map in accordance with the engine speed N. Subsequently, the data to is subtracted from the data T to calculate a time duration t. The unit also has a two-dimensional map for storing the relationship between each time duration t and the corresponding rate G/N in correspondence with each of the present engine speeds. A corresponding rate G/N is read out from the two-dimensional map in response to the calculated time duration t.

Abstract: An engine control system is disclosed which includes engine idle speed control apparatus which implements a closed loop idle speed control by varying the amount of air provided to the engine by an air bypass valve. The control system develops an engine torque polarity signal related to the difference between actual current manifold air pressure and the average of the manifold air pressure which exists during engine idle. The torque polarity signal is utilized to implement engine deceleration control by selectively providing additional air and/or reduced fuel to the engine to implement engine fuel mixture enleanment during deceleration conditions. The engine idle speed control apparatus calculates an error signal related to the difference between actual engine speed and a calculated desired engine idle speed.

Abstract: A fuel supply of an internal combustion engine is controlled by sampling a vacuum level within an intake pipe of the engine and a value corresponding to the engine rotational speed at predetermined sampling intervals, subsequently correcting a latest sampled value P.sub.BAn of the vacuum level with a latest sampled value M.sub.en of the value corresponding to the engine rotational speed to produce a corrected value P.sub.BA, and then determining fuel supply amount in accordance with the corrected value P.sub.BA. By determining the fuel supply amount in this way, hunting of the engine rotational speed especially during idling operation of the engine is prevented.

Abstract: A method and apparatus for controlling operating conditions of an internal combustion engine based upon sensed operating parameters of the engine expressed in the form of pulse signals, wherein the frequency of the pulses is representative of the sensed parameter. The pulse intervals of the sensed operating parameter signals are measured to the fractional level before being stored and employed by a CPU to calculate data applied to control predetermined operating conditions of the engine, such as the fuel flow rate and the ignition timing. The inventive method and apparatus attain greater operating stability for steady-state operations and excellent response under transient conditions of the engine.

Abstract: The invention is directed to an apparatus for metering an air-fuel mixture to an internal combustion engine with an extreme-value control arrangement for controlling to a minimal specific consumption of fuel. The extreme-value control arrangement includes a test signal generator for acting upon the fuel metered to the engine. The rotational speed and a fuel metering signal are applied by the extreme-value control arrangement as actual information with respect to the minimal specific fuel consumption. In particular, the quantities of rotational speed change and the change in duration of fuel injection are utilized to determine the minimal consumption in the case of an internal combustion engine equipped with fuel injection. Further, for a minimal consumption control, it has been shown to be advantageous to consider information as to which gear of the transmission of the engine is in place.

Abstract: A method of air-fuel ratio control for automotive internal combustion engine in which the amount of fuel to be supplied to the internal combustion engine is determined in accordance with the amount of air passing through a main air intake path, and the amount of air in a bypass is controlled in a manner to attain a predetermined air-fuel ratio for a lean mixture gas which is determined by a predetermined operating mode of the automobile. The amount of supplied fuel which changes with the amount of air in the bypass is thus corrected to perform the lean mixture gas operation in the predetermined operating mode.