Abstract: A method and apparatus for enhancing the cold starting performance of a spark ignition, internal combustion engine fueled with an alcohol-based fuel mixture is described. The quantity of fuel mixture delivered to the engine is regulated to establish a combustible fuel vapor-air mixture in each engine cylinder during cranking, while restricting the accumulation of unvaporized fuel in the each cylinder so as not to exceed a predetermined amount. In addition, each cylinder spark plug is provided with an ignition current having a peak magnitude sufficient to achieve voltage break down across each spark plug arc gap, when each gap is resistively loaded due to wetting in accordance with the predetermined amount of accumulated unvaporized fuel. Preferably, the quantity of fuel delivered to the engine during cranking is reduced at a substantially exponential rate as a function of the cumulative number of revolutions the engine is rotated during cranking.

Abstract: The fuel control routine of an engine control module sets a cold enrichment schedule used for engine starting when the engine is cold. The enrichment value is dependent on coolant temperature. To prevent plug fouling in a new vehicle subject to short engine run times, the enrichment value is reduced if the mileage is below 50 miles, the coolant temperature is within set limits and the previous engine run time was shorter than a set period.

Abstract: The invention relates to an auxiliary unit included in a control arrangement for an internal combustion engine. An NTC-resistor (6) which is subjected to the effect of engine temperature of engine cooling-water temperature, is connected to a control system (5) which monitors the resistance of the NTC-resistor (6), this resistance varying with engine temperature, and utilizes this variation in resistance to change temperature-dependent control parameters for engine operation. The auxiliary control unit is connected to NTC-resistor (6). The auxiliary control unit applies an elevated voltage across the NTC-resistor over a predetermined period of time after an engine cold start, so as to deceive the control system (5) in indicating that the resistor is colder than it actually is.

Abstract: A method and a controller for supplying a fuel to a plurality of cylinders of an internal combustion engine, in which engine operation conditions including the operating temperature of the engine are detected by various sensors attached to the engine and by using a microcomputer, and the fuel is successively supplied by being injected to the engine cylinders based on the detected engine operation conditions. The timing of fuel injection into each of the plurality of cylinders is shifted from an exhaust stroke period to a suction stroke period according to the operating temperature of the engine among the detected engine operation conditions.

Abstract: An engine speed control apparatus including an air control valve which controls the cross-sectional area of a bypass passage provided so as to bypass the throttle valve of the engine. The apparatus also includes a control unit which controls a degree of opening of the air control valve on the basis of a synthesized quantity which is obtained by synthesizing a basic air quantity for maintaining a target engine speed and an engine speed feed-back correction quantity which effects to eliminate an error between the target speed and an actual engine speed. An atmosphere pressure sensor is used to detect an atmospheric pressure, and a correction circuit is used to ensure that the synthesized quantity corresponds with the detected atmospheric pressure the engine is started.

Abstract: An automotive engine is provided with a fuel control system having a fuel injector for injecting a properly controlled quantity of fuel into cylinders of the automobile engine. The control system is adapted to cause the fuel injector to inject an increased quantity of fuel when an engine control value, relative to which the automotive engine changes its speed of rotation for a decision as to whether the automotive engine is in an acceleration state, is higher than a critical level. The control system also detects the transmission coupled to the automobile engine, and changes, when a temperature of the automotive engine is lower than a preselected temperature, the critical level according to the type of transmission detected.

Abstract: An engine start control system wherein the engine is restarted after the engine is scavenged without supplying of fuel from a fuel injection valve by cranking only when the engine almost stops as well as when a driver wants to scavenge. The driver's intention to scavenge a combustion chamber of the engine is detected by a control switch which the driver can turn on or off or an opening degree of a throttle valve in an intake passage when the opening degree is equal to or exceeds a predetermined value.

Abstract: A digital fuel control system for a small internal combustion engine having a pressure sensor for detecting the instantaneous pressure in the air intake manifold of the engine to generate air pressure data. A microprocessor responsive to the air pressure data generates a fuel quantity output signal indicative of the quantity of fuel to be delivered to the engine. A fuel metering apparatus responsive to the fuel quantity output signal generated by the microprocessor meters the fuel being delivered to a fuel delivery mechanism which delivers the fuel into the air intake manifold of the engine. The microprocessor in response to the air pressure data generated by the pressure sensor determines the engine's speed and the average pressure of the air inhaled by the engine. The engine speed data and air pressure data address a look-up table to extract data indicative of the fuel requirements of the engine.

Abstract: An air-fuel ratio control device for an vehicle engine, by which the air-fuel ratio of the air-fuel mixture supplied to a vehicle engine is changed. The device sets the air-fuel ratio to a lean mixture when the engine coolant temperature is higher than a predetermined value and the vehicle speed is higher than a value determined by a time elapsed after engine startup.

Abstract: This invention includes a method and apparatus for starting an internal combustion engine with a reduced starting time. That is, there is a reduced delay before the first combustion event occurs in the engine. Only a single engine position sensor is used. The method includes injecting fuel into a cylinder before true engine position is determined and applying an ignition pulse to the cylinder and firing the ignition coil after fuel has been injected into the cylinder. Advantageously, injecting fuel for the cylinder is done after determining the engine is turning and determining the engine has a rotational rate below a predetermined parameter.

Abstract: With a process and an apparatus for cold-start control in an electronic internal combustion engine system, the combustion chambers of the internal combustion engine are supplied, during starting, with the increased fuel feed. The fuel feed per an ignition interval (TD.sub.n) is effected by a plurality of short cold-start injection pulses generated at increased frequency at linear time intervals with respect to one another in respective ignition intervals. This frequency control replaces the normal formation of fuel injection pulses corresponding to half-periods of crankshaft rotation, during starting, and is cancelled upon commencement of preset fuel reduction thresholds. Owing to the fuel atomisation attained, there results a spontaneously ignitable mixture, so that a cold start is still possible even at extremely cold temperatures.

Abstract: Herein disclosed is a fuel injection rate control system for starting a two-cycle engine having a fuel injection valve, which comprises: means for correcting the starting basic fuel injection rate, which is stored in advance in terms of an engine temperature, in accordance with the cranking engine speed at the enging starting time; and means for performing a correction in accordance with the cranking time period, wherein the improvement comprises, as the means for correcting the starting basic fuel injection rate in accordance with the cranking engine speed: first engine speed correction coefficient setting means for setting a first engine speed at a first start of the engine; means for deciding second later starts of the engine; and second engine speed correction coefficient setting means for setting an engine speed correction coefficient smaller than that of the first engine speed correction coefficient setting means when the second and later starts of the engine are decided by the decision means.

Abstract: An air-fuel ratio control method controls the air-fuel ratio of an air-fuel mixture supplied to an internal combustion engine having spark plugs, and heaters for heating the air-fuel mixture in the vicinity of respective ones of the heaters, the air-fuel mixture containing a fuel which is poor in atomizing characteristic at a low temperature. The method comprises the steps of (1) determining whether or not a temperature of the engine is lower than a predetermined value, (2) determining whether or not the engine is being cranked, (3) detecting an amount of electric current flowing through each of the heaters, and (4) controlling an amount of fuel supplied to the engine based on the detected amount of electric current when it is determined that the temperature of the engine is lower than the predetermined value and at the same time the engine is being cranked.

Abstract: Disclosed is a system for controlling the fuel injection quantity at the start of a two-cycle engine, in which a predetermined amount of a fuel is preliminarily injected when a key switch of the engine is turned on, the revolution speed of the engine is smaller than a reference value and the opening degree of a throttle valve takes a predetermined change pattern.

Abstract: A fuel supply device for an internal combustion engine comprises at least one electrically controlled injector feeding fuel under pressure into the intake manifold of the engine and an electronic control circuit connected to sensors responsive to operating parameters of the engine, particularly the engine speed, and delivering periodic signals of variable duty ratio to the injector. The control circuit applies asynchronous electrical signals to the injector as long as the running speed of the engine does not reach a predetermined threshold value. The asynchronous signals have a frequency very much higher than that which the synchronous operative law would cause.

Abstract: A fuel injection control apparatus for an internal combustion engine adapted to operate, at a predetermined timing, the time of starting fuel injection on the basis of a revolution speed of the engine and a fuel injection time and to start fuel injection by using the latest information among the time of starting fuel injection operated, characterized in that the newest information of the time of starting fuel injection is corrected based on the temperature of cooling water for the engine.

Abstract: The invention is directed to a sequential fuel injection method wherein the first injection end time point is determined at which the preinjections end. In addition, the first intake end time point is determined at which a signal occurs for the first time after the start of the method which is evaluated as a signal that indicates the end of an induction operation. Furthermore, a determination is made for which cylinder the above-mentioned time point applies. If the first-mentioned time point lies ahead of the second-mentioned time point, the sequential fuel injection is started for the determined cylinder. For the opposite position of the mentioned time points, the injection valve for that particular cylinder is driven whose induction cycle follows the determined cylinder with the injection valve being so driven that the entire fuel quantity is injected which was computed for the sequential injection.

Abstract: In a control device (14) for fuel injection and/or spark ignition in an internal combustion engine, a first datablock (16) is programmed for operation in accordance with engine operating parameters (BM, P, L, n, T) but without lambda control when the engine is cold and a second datablock (18) is programmed for operation with lambda control when the engine is warm. A switching logic (26) switches in the first datablock (16) when the engine is started below a lower threshold (T.sub.1) and switches over to the second datablock (18) when the temperature rises above a higher threshold (T.sub.2).

Abstract: A fuel injection controlling device for a two-cycle engine includes an electronic fuel injection system having a fuel injection quantity determining device for determining a fuel injection amount in response to rotational speed and throttle opening of the engine. At engine start, the controlling device, in response to operation of an engine kick starter, sequentially decreases starting fuel amount as the number of actuations of the kick starter increases. Fuel injection amount is also decreased in response to increasing engine temperature.

Abstract: A method for injecting fuel into an internal-combustion engine. In a method for operating an injection system, injection into the individual cylinders is carried out by groups before a synchronization time at which the position of the individual signals is known on the basis of two transmitters. The groups are selected such that an injection into an open intake valve is avoided. Upon transition to the normal, sequential injection, the first cylinder into which injection is carried out is identified such that no double injection at a cylinder occurs. This method avoids a lengthening of the start time due to the lack of injection and also avoids an increased exhaust emission due to bank injection before the synchronization time.

Abstract: An operation control system for internal combustion engines at and after starting has an engine temperature sensor, a control valve for controlling the amount of intake air to be supplied to the engine, and a valve opening determining device responsive to an output from the engine temperature sensor for determining the opening of the control valve. The valve opening determining device sets the opening of the control valve at the start of the engine to a value such that the intake air amount is smaller as the engine temperature is lower. A fuel amount determining device is responsive to the output from the engine temperature sensor for determining the amount of fuel to be supplied to the engine at starting. A correction value determining device is responsive to the opening of a throttle valve of the engine for determining a correction value for the fuel amount in such a manner as to increase the fuel amount at a larger rate as the throttle opening is larger.

Abstract: An engine control system derives a basic fuel supply amount on the basis of preselected parameters including an intake air volume associated value and modifies the derived basic fuel supply amount in such a manner that the modified fuel supply amount becomes equal to the basic fuel supply amount derived on the basis of the preselected parameters when the engine is not in an acceleration state satisfying a predetermined first condition, and the modified fuel supply amount varies at a greater rate than variation rate of the basic fuel supply amount derived on the basis of the preselected parameters when the engine is in the accelerating state satisfying the predetermined first condition. The basic fuel supply amount as modified may be further modified with a correction value during the engine accelerating state satisfying a predeermined second condition.

Abstract: A method for carrying out a hot start in an internal combustion engine has a hot start condition that is recognized on the basis of the coolant temperature and the intake air temperature. A hot start identifier is stored when the coolant temperature and the intake air temperature have both reached a predetermined limit value at least once during a post-operation time after the internal combustion engine is turned off. At the next start of the internal combustion engine, the hot start is then carried out when the hot start identifier is stored and the coolant temperature still lies above its limit value. The method is thus based on temperature sensors that are already present in the motor control system. Therefore, no additional temperature sensors, for measuring the temperature of the fuel, are required.

Abstract: A fuel injection control device comprising an electronic control unit in which a changing rate of the amount of air fed into the engine cylinders per one revolution of the engine is calculated. The amount of fuel injected by the fuel injector is increased and decreased when the changing rate becomes positive and negative, respectively. The decrease in the amount of fuel injected by the fuel injector is prohibited even when the changing rate becomes negative until a predetermined time has elapsed after the engine is started.

Abstract: Routines are run which briefly monitor a selected parameter and ascertain, based on the magnitude of the parameter, the use of heavy, regular or light fuel. These routines set correction factor values which are used to modify fuel injection, ignition timing and the like, during transient modes of engine operation. Tables used in the identification are recorded in two-dimensional form. Following an identification and correction factor determination, the programs are adapted to terminate very early in the run. Depending on the change in fuel tank volume, previously obtained data is assumed to still hold true and analytical routines forshortened to obviate redundant re-analysis and lighten processor load.

Abstract: In a process for fuel injection in a multiple-cylinder internal combustion engine, opening signals for the respective injection valves of the individual cylinders are produced as a function of reference signals which are synchronous with the crankshaft. All injection valves are first controlled jointly after the ignition switch is switched on and the sequential opening signals for the sequential fuel injection are produced after the synchronization has been recognized. In order that the sequential fuel injection be switched on rapidly after the start of the internal combustion engine or after a disruption of the synchronization, wherein the fuel quantity injected into opened inlet valves is to be minimized, the opening signals are fed to the injection valves in a simultaneous manner, at least in a phase (a) until the synchronization has been recognized.

Abstract: Misfire is detected in an internal combustion engine during its starting mode by analyzing the engine speed profile. Average speed is determined for 60.degree. increments of crankshaft rotation. If an increment midway between top dead center positions has a higher speed than the previous increment and a higher speed than cranking speed, combustion occurred, otherwise a misfire occurred. When misfires are detected for a particular cylinder the calculated fuel allotment for that cylinder is reduced in accordance with the number of consecutive misfires for that cylinder.

Abstract: A method and apparatus of controlling the direct injection of fuel directly into the combustion chamber of an engine by a charge of gas, wherein the control of the timing of injection of the fuel includes at the commencement of start up of the engine, adjusting the timing of injection so injection occurs at a timing earlier in the combustion chamber cycle than the normal timing of injection for idle running; and in response to the engine reaching a predetermined speed or rotation during start up, the timing of injection is progressively adjusted each engine cycle towards the normal timing of injection at idle running.

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: To control the quantity of fuel supplied to an I.C. engine, a sensor generates an exhaust gas component concentration signal. If the present fuel supply quantity does not exceed a reference quantity, the fuel supply is set according to engine operation parameters. If the preset quantity is greater than the reference quantity for a predetermined reference time, the fuel supply is set without regard to the signal. The reference time is changed as a function of engine temperature.

Abstract: A fuel supply control system for an internal combustion engine having a throttle body, and a fuel injection valve arranged in an intake manifold upstream of the throttle body for supplying fuel to all cylinders. An air throttle valve has a valve body having a notched opening formed therein and disposed to be opposite the nozzle of the fuel injection valve to increase the flow speed of intake air in the vicinity of the nozzle when the air throttle valve is fully closed. An electronic control unit controls the fuel injection valve in response to operating conditions of the engine. The electronic control unit causes the air throttle valve to be fully closed when a predetermined low rotation-speed operating condition of the engine, in which at least the rotational speed of the engine is lower than a predetermined value, is satisfied. The predetermined value of the rotational speed of the engine is set such that the lower the atmospheric pressure the smaller the predetermined value.

Abstract: In fuel injection system of an internal combustion engine of a vehicle, a fuel injection valve is activated to inject pre-start fuel in response to turn-on of a main switch by a vehicle driver. A starter motor is not activated until a predetermined delay period (T.sub.D) elapses after the turn-on of the main switch. During the delay period (T.sub.D) the injected fuel is vaporized. After the delay period (T.sub.D) the vaporized fuel is taken into engine cylinders when the engine is cranked by the starter motor so that fuel is ignited in the engine easily.

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 engine start control apparatus of the type that the running of the engine is controlled by a controller in accordance with data obtained from at least one sensor mounted on the engine and stored in a backup memory. The engine start control apparatus includes a starting condition detector unit for detecting a start ready state of the engine and outputting a start ready signal, a signal processing unit for processing an output signal from the sensor and storing the processed result into the backup memory in response to the start ready signal from the starting condition detector unit, a start detection unit for detecting the start of the engine and a power supply unit for supplying a power voltage to the controller in response to an output from the start detection means.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine supplies an output signal from an O.sub.2 sensor detecting the concentration of oxygen in the exhaust gas to an electronic control unit having a microcomputer, and a control valve of the carburetor is controlled by a control signal from the microcomputer so as to control the air-fuel ratio in a feedback manner. A desired upper limit value is set for the control signal and, when the control signal exceeds this upper limit value in a transient operating condition of the engine, when its operating state is shifted from an idling state to a partial operating state, the microcomputer promptly changes the rich air-fuel ratio to a proper value.

Abstract: A self-monitor system has a delay circuit active in response to the end of engine cranking to enforce a predetermined time delay which is long enough for battery voltage to recover to normal levels. The delay circuit outputs a command for execution of self-monitoring operations by the digital control system after the predetermined time delay. The self-monitor system in the digital control system is responsive to the command from the delay circuit to check the battery voltage and to apply dummy loads to system elements at levels sufficient to simulate actuation of the elements to be checked, such as sensors, actuators and/or indicators. By enforcing the time delay time, the influence of temporary drops in battery voltage due to overloading during engine cranking can be fully avoided.

Abstract: A fuel supply control system for an internal combustion engine comprises a start detecting device for detecting a starting condition of the engine, and a starting fuel supply device for supplying an amount of fuel required for starting the engine which corresponds to an output generated from a device for detecting an engine temperature, when the start detecting device detects the starting condition of the engine. A timer is associated with the start detecting device for counting time elapsed from the time the start detecting device detects the starting condition of the engine and generating an output corresponding to the elapsed time. A fuel decreasing device is responsive to respective outputs from a throttle opening sensor and the timer, for decreasing the amount of fuel for starting the engine, supplied by the starting fuel supply device.

Abstract: A method of controlling the air/fuel ratio for an internal combustion engine set a base value of air/fuel ratio control in accordance with detected engine parameters, and the base value is corrected by a base correction value in order to compensate for the error of the base value. The speed of change in the correction value in the learning control operation is increased when the engine speed is low, or for a predetermined time period after a hot starting of the engine.

Abstract: A fuel injection control system for an internal combustion engine achieves efficient combustion during starting the engine and reduces excess fuel consumption. While the engine has not warmed yet after starting, extra fuel is supplied to the engine by a starting fuel supply means. When the engine rotational speed exceeds a predetermined first speed corresponding to an almost complete combustion state, the fuel injection amount from the starting fuel supply means is gradually decreased. When the engine rotational speed is determined to exceed a predetermined second speed corresponding to a stable combustion state, the extra fuel from the starting fuel supply means is terminated, and the fuel injection amount based on the engine start control is changed over to the amount based on an air-fuel ratio control for post-starting state.

Abstract: A fuel supply control method for a multicylinder internal combustion engine equipped with a fuel supply control system including a main fuel injection valve disposed in the intake passage upstream of the throttle valve, and an auxiliary fuel injection valve disposed in the intake passage donwstream of the throttle valve and upstream of the intake manifold, for controlling the fuel supply control system according to operating conditions of the engine.

Abstract: An intake system utilizing an air-fuel control which is changed in accordance with the coolant temperature. When the coolant temperature is lower than the first coolant temperature, an open loop control is carried out in accordance with the coolant temperature so that a fluctuation of the air-fuel ratio can be restricted so as to obtain a stability. An air-fuel feedback control is carried out between the first and second coolant temperatures wherein the air-fuel ratio is maintained at the stoichiometric value so that an increase of NO.sub.X emitted from the engine can be suppressed. In the region in which the coolant temperature exceeds the second temperature, an air-fuel feedback control is carried out in the lean mixture side of the stoichiometric value in accordance with the coolant temperature to thereby improve the emission performance of the engine.

Abstract: Disclosed is a fuel injection control apparatus wherein the quantity of fuel supplied to an internal combustion engine is derived from engine operating parameters including a voltage signal which is generated by electromagnetic induction as a function of engine speed. A fuel injection quantity calculation circuit derives the fuel quantity in accordance with the detected operating parameters of the engine. A fuel injection controller provides injection of fuel in accordance with the calculated fuel quantity when the sensor voltage is valid and provides forced fuel injection regardless of the calculated fuel quantity when the sensor voltage is invalid and the engine starter is being operated.

Abstract: After starting of an internal combustion engine, a quantity of fuel to be supplied to the engine is increased by the use of a fuel increment, and at the same time a period of time is counted which elapses from the time an oxygen concentration sensor has its internal resistance decreased below a predetermined value. When the period of time counted exceeds a predetermined period of time, the increase of the quantity of fuel is terminated and simultaneously calculation of a correction value responsive to oxygen concentration in exhaust gases sensed by the sensor is started, and the quantity of fuel is corrected by means of the correction value calculated. A temperature in the engine intake system is sensed, and the above predetermined period of time is to a larger value as the sensed intake system temperature is higher.

Abstract: A starting control for fuel injection systems of internal combustion engines is suggested in which an injection time (te.sub.VER), which is dependent on the engine starting temperature (T.sub.MS), is determined in the starting phase. In the starting phase, this injection time (te.sub.VER) follows the curve of special starting characteristic lines. A continuous transition to performance characteristics injection time (te.sub.KF) is effected by means of a comparator. A smooth transition from the starting phase to normal operation is obtained in this way.

Abstract: A temperature of an internal combustion engine is sensed when the engine is started and elapsed time from engine start is also sensed. Engine intake air temperature is estimated on the basis of the sensed engine temperature and sensed elapsed time. The operation of the engine is controlled in accordance with the estimated engine intake air temperature.

Abstract: A fuel supply control method for an internal combustion engine, including the steps of effecting after-start fuel increasing control wherein an initial value of a fuel increment is set to a value dependent upon a temperature of the engine upon generation of a predetermined control signal immediately after the start of the engine, the fuel increment is progressively decreased from the set initial value in synchronism with subsequent generation of the predetermined control signal, and a fuel quantity corrected by the progressively decreased fuel increment is supplied to the engine, and effecting air-fuel ratio feedback control, which is executed on condition that a predetermined feedback control condition is fulfilled after the start of the engine, wherein a correction coefficient is set to a value dependent upon the concentration of an ingredient in engine exhaust gases, sensed by an O.sub.2 sensor, and a fuel quantity corrected by the set correction coefficient is supplied to the engine.

Abstract: A method of controlling the quantity of fuel supplied to an internal combustion engine after starting thereof. An initial value of a fuel increment is set in response to a temperature of the engine immediately after the start of the engine, and is subsequently decreased with the lapse of time. A quantity of fuel set by the use of the thus decreased fuel increment is supplied to the engine. The rate of decrease of the fuel increment is set to a value corresponding to a sensed temperature representative of fuel injection valves of the engine. Preferably, the rate of decrease is set to a smaller value when the sensed temperature is equal to or higher than a value corresponding to the boiling point of the fuel, than a value set when the former is lower than the latter.

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: While an exhaust gas sensor having an output characteristic linear with respect to the concentration of a specific component in exhaust gases from an internal combustion engine, the opening of an automatic choke valve is controlled in response to the degree of warming-up of the engine. From the time of activation of the exhaust gas sensor to the time of completion of warming-up of the engine, the automatic choke valve and an air-fuel ratio control valve arranged in an air passage bypassing a throttle valve in an intake passage of the engine, are driven so as to achieve a desired air-fuel ratio, respectively, when the difference between the desired air-fuel ratio and actual one is larger than a predetermined value, and when the difference is smaller than the predetermined value. After completion of warming-up of the engine, the air-fuel ratio control valve is driven in response to operating conditions of the engine so as to achieve the desired air-fuel ratio.

Abstract: A fuel supply control method for controlling the quanity of fuel being supplied to an internal combustion engine, in a feedback manner responsive to the output of a means for detecting the concentration of an ingredient in exhaust gases emitted from the engine. When the engine is operating in a predetermined low speed operating region wherein the rotational speed of the engine is lower than a predetermined speed higher than the idling speed and the intake pipe absolute pressure is higher than a predetermined value higher than a value normally assumed at idle of the engine, the above feedback control is interrupted and the fuel quantity is increased by a predetermined amount so as to make the air/fuel ratio of a mixture being supplied to the engine richer than a theoretical mixture ratio.