Abstract: In a method for adjusting air and fuel masses for a multi-cylinder internal combustion engine with individual injection for each cylinder, the fuel mass for each injection operation is calculated taking into account the probable intake-pipe pressure during the opening time of the inlet valve. After a change of the accelerator pedal, the throttle flap is only adjusted when the fuel masses decisive for the new throttle-flap position have been calculated and substantially ejected.

Abstract: An apparatus for controlling a quantity of fuel injected into an internal combustion engine comprises a sensor for detecting atomspheric pressure, a sensor for detecting a load condition of an internal combustion engine, and an electronic control device including a microprocessor.

Abstract: A system for controlling an ignition timing control in a fuel injection internal combustion engine whereby, upon an acceleration of the engine, in addition to a synchronous injection carried out at a predetermined timing during one cycle of the engine, an asynchronous injection is carried out regardless of the timing at which the synchronous injection is obtained. An ignition timing is basically controlled to obtain a maximum combustion pressure. A control of the retarding of the ignition timing from the basic timing is obtained upon a detection of an acceleration condition. A degree of acceleration is determined from a total amount of the asynchronous injection, and an amount by which the ignition timing is retarded is varied in accordance with the detected degree of acceleration.

Abstract: A fuel injection system for a two cycle engine having main fuel injectors that inject directly into the engine combustion chambers and a sub or auxiliary fuel injector that injects into the induction system only under high load conditions to effect better piston cooling. Once the sub fuel injector begin to inject, then the amount of fuel per cycle injected by the main fuel injectors is decreased. The sub injector injects into a common manifold for a multiple cylinder engine and injects only one per crankshaft revolution.

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: A fuel injection device of an engine for a vehicle having a power transmitting system connected between the engine and the drive wheel. The relative angle of torsion between the opposed ends of the power transmitting system is maintained at the converging angle of torsion determined by a required amount of fuel when a cruising operation of the engine is carried out. When the required amount of fuel is changed from a first required amount of fuel to a second required amount of fuel, a pre-injection is carried out prior to the main injection. The amount of fuel and the injection time of the pre-injection and the start time of the main injection are determined so that the relative angle of torsion becomes equal to the converging angle of torsion determined by the second required amount of fuel when the main injection is started, and that the relative angle of torsion is maintained at the converging angle of torsion determined by the second required amount of fuel after the main injection is started.

Abstract: Fuel injection increasing timing occurs differently from the timing of changing an intake air flow and an exhaust gas flow, wherein the fuel injection quantity is controlled by a detected intake pressure and an engine which increases the fuel injection quantity at accelerating comprises a system for changing an exhaust gas glow of an exhaust system by a sequential turbo control and changing an intake air flow of an intake system by a dynamic effect of an intake air. The fuel supply is delayed by the fuel injection quantity increase at accelerating. This delay and pressure difference of intake air and exhaust gas by changing intake air flow and exhaust gas flow work together to prevent the air fuel ratio from fluctuating greatly, and a good engine combustion is maintained.

Abstract: A fuel delivery control apparatus for use with an internal combustion engine for controlling the amount of fuel metered to the engine based upon engine operating conditions. A control unit is provided for calculating an acceleration enrichment related correction factor from a relationship programmed into the control unit to correct the amount of fuel metered to the engine so as to provide acceleration enrichment for a predetermined period of time after the engine acceleration starts. This relationship defines the acceleration enrichment related correction factor as a function of selected engine operating conditions. The relationship is corrected based upon recent engine operating conditions.

Abstract: An air-fuel ratio control device comprising a memory which stores the relationship between the degree of opening of the throttle valve and the absolute pressure in the intake passage, which pressure is produced when the engine is in a cruising state. When a difference between the blunt value of the actual absolute pressure in the intake passage and the absolute pressure stored in the memory exceeds a fixed value, the air-fuel mixture is changed from the mixture for the stoichiometric air-fuel ratio to a lean mixture.

Abstract: In a fuel control system for an internal combustion engine, fuel is injected in a quantity the direct delivery part of which provides a desired quantity of fuel to be actually fed to the engine together with the drawn part of the intake-manifold wetting fuel. The quantity of the intake-manifold wetting fuel on the basis of which the quantity of the drawn part is calculated is calculated on the basis of the quantity of the adhering part of the fuel which was injected by the preceding injection and the quantity of the residual part of the preceding intake-manifold wetting fuel.

Abstract: An apparatus to calculate the intake pipe pressure using the degree of throttle opening and the engine speed, to use this intake pipe pressure to calculate a current intake pipe pressure, and to determine a predicted value from this current intake pipe pressure and control fuel injection duration and/or spark timing. Becuase changes in the atmospheric pressure and changes in the air amount flowing through a bypass bypassing the throttle, etc., cause errors in the values predicted for the intake pipe pressure, there are irregularities in the exhaust emission. the atmospheric pressure and the intake pipe pressure, etc., detected by a pressure sensor are used to correct the predicted value, and prevent irregularities and the like in exhaust emissions.

Abstract: A fuel injection control system for an automotive engine, including a device which, before an intake stroke cycle, estimates what an estimated throttle opening degree and an estimated engine speed will be for the engine after a predetermined time period in the intake stroke cycle has lapsed, based on the throttle opening degree and engine speed and calculates a first fuel injection quantity to be injected before an intake stroke cycle, and a device which, during the intake stroke cycle, calculates a second fuel injection quantity and computes an asynchronous interrupted fuel injection quantity to be injected during the intake stroke cycle, based on the difference between the first and second fuel injection quantity.

Abstract: A fuel supply control system performs asynchronous fuel injection in response to acceleration demand for injecting a controlled amount of fuel irrespective of an engine revolution cycle. The amount of fuel for asynchronous injection in an engine transition state from engine decelerating state, in which fuel cut-off is performed, to engine acceleration state, is determined on the basis of a set value which is a latched fuel injection upon initiation of fuel cut-off operation, and an instantaneous fuel injection amount derived on the basis of the instantaneous fuel injection control parameters. The set value is modified in relation to an amount of fuel left on a periphery of an induction system.

Abstract: A system and method for recognizing a stagnation state for a vehicle are disclosed in which a running characteristic pattern of the vehicle is derived on the basis of running parameters such as the vehicle speed, acceleration of the vehicle, and deceleration of the vehicle, and whether the running characteristic pattern substantially coincides with a running characteristic pattern peculiar to a state in which the vehicle runs in the stagnation state.

Abstract: With regard to the engine control method which determines control variables for the individual cylinders of a multicylinder internal combustion engine independently of one another, this specification discloses improved control method and apparatus whereby the optimum control variables are determined. The control method of a multicylinder internal combustion engine according to this invention includes a step of detecting data representing the operating condition of the engine, a step of storing data, a step of determining a first control variable at a certain time of a certain stroke of each cylinder according to the stored data, and a step of determining a second control variable at a later time in the stroke according to the same stored data.

Abstract: An air-fuel ratio control system in an internal combustion engine, whereby an acceleration condition is detected to obtain an enrichment correction of a fuel injection amount. An occurrence of a mild acceleration is detected by calculating a value of a rate of change in a parameter of an engine load, such as a degree of opening of a throttle value, between adjacent timings, accumulating values of the rate of change of the engine load parameter during a sampling period, and comparing the accumulated value with a predetermined threshold value.

Abstract: A motor vehicle has a continuously variable belt-drive transmission having a clutch means which engages when speed of an engine is higher than a clutch engaging speed. A plurality of basic pulse widths for injecting fuel are stored in a memory arranged in accordance with the engine speed and opening degree of a throttle valve. Some of the basic pulse widths in a speed range lower than the clutch engaging engine speed are increased for acceleration of the engine. One of the basic pulse widths is retrieved in accordance with the actual engine speed and the throttle valve opening degree, and a fuel injection pulse width is calculated based on the retrieved basic pulse width.

Abstract: In the control of the sequential fuel injection in an internal combustion engine, where the engine load is set based on the opening of the throttle valve and the engine revolution number and the quantity of correction of the fuel supply quantity is determined based on the ratio of the change of this engine load and the time up to a predetermined time during the intake stroke, this time is computed for each cylinder and the correction quantity is set individually for the respective cylinders.

Abstract: An electronic control system for an internal combustion engine includes a plurality of first sensors for measuring a drive action taken in accordance with a driver's intent, a plurality of second sensors for measuring operating conditions of an engine, a plurality of actuators for controlling the engine, a unit for setting a target reference by selecting one among a plurality of target references for engine control, and a unit for manipulating the actuators responsive to the established target reference to control the engine.

Abstract: An automotive fuel injection system for detecting as quickly as possible the occurrence of acceleration without employing a throttle sensor to thereby perform an asynchronous fuel injection for the purpose of maintaining the air-to-fuel ratio of the combustible air-fuel mixture at an optimum value during the acceleration of the automotive engine. The automotive fuel injection system comprises a device for comparing the pressure inside the fuel intake system with an average value of the pressures inside the fuel intake system. When the pressure prevailing in the fuel intake system deviates by a predetermined quantity from the average pressure inside the fuel intake system, acceleration is deemed as actually occurring in the automotive engine and, hence, asynchronous fuel injection is effected substantially simultaneously with the detection of the occurrence of engine acceleration.

Abstract: A fuel injection control apparatus which controls the regular fuel injection amount based on a control law determined in accordance with a fuel dynamic model showing the dynamics of fuel flowing into an engine cylinder using as state variables the amount of fuel sticking to the walls of the intake passage and the amount of fuel evaporating in the intake passage.During deceleration operation, the regular fuel injection is stopped, the control law correction fuel injection amount is determined from the parameter values of the fuel dynamic model, the true values of the rate of fuel sticking to the walls of the intake passage and the rate of remainder of sticking fuel, which are parameters of the fuel dynamic model, are identified based on the amount of fuel injection, the amount of air flowing into the cylinder, and the air-fuel ratio, and the control law is corrected based on the results of the identification.

Abstract: A fuel control system for an internal combustion engine of an automotive vehicle controls an air-fuel ratio using feedback so as to determine a proper air-fuel ratio by constantly monitoring the exhaust to verify the accuracy of an air-fuel mixture setting. The fuel control system halts the feedback fuel control and forcibly causes an increase of fuel so as to enrich an air-fuel mixture setting when an engine operating condition shifts into a specific zone of engine load in which the engine operates at high loads. The forced increase of fuel is delayed for a predetermined time period when the engine operates at speeds within a specific speed zone in the specific load zone, the time period being changed so as to be longer or shorter according to engine speeds in the specific speed zone.

Abstract: A fuel evaporation quantity is estimated based on engine speed and opening degree of a throttle valve. The quantity of fuel to be injected is provided based on the estimated fuel evaporation quantity. A weight for a weighted mean is changed in accordance with the engine operating condition. A smoothed fuel injection quantity is provided by the weighted mean with the weight.

Abstract: A fuel control system for an automobile engine includes various sensors for detecting the running conditions of the engine, an injector or injectors for supplying fuel to the engine, and a control unit for reducing or cutting the amount of fuel to be supplied to the engine in response to the sensors at the time of deceleration and for controlling the injectors so that the amount of fuel to be supplied to the engine at the time of removal of deceleration is less than the normal amount corresponding to the running conditions of the engine. The control unit further operates so that the amount of reduction of the fuel supply is less in an engine equipped with an automatic transmission than in an engine equipped with a manual transmission. The control unit also operates so that the initial amount of fuel to be supplied to the engine at the time of removal of deceleration is less in the engine equipped with the manual transmission than in the engine equipped with the automatic transmission.

Abstract: A control device for an automotive engine provided with a fuel injection valve determines the current value of a parameter (e.g. the mean effective combustion pressure) indicative of the output power of the engine, and compares it to the target value thereof determined, for example, from the temporal change of the throttle opening degree. At least one of the parameters: the driving pulse width of the fuel injection valve (corresponding to the amount of fuel supply), the ignition timing, and the amount of intake air, is selected as a manipulated variable and controlled so as to reduce the difference between the current and target values of the parameter.

Abstract: A method and device for controlling an engine mounted on a vehicle substantially suppresses pitching or surging of the body of the vehicle during acceleration even when the driver abruptly depresses an accelerator pedal, thereby markedly improving riding comfort. A valve such as a throttle valve in an engine intake passage is operatively associated with an accelerator pedal such that the opening degree of the valve is changed by operation of the accelerator pedal to control at least one of the amount of intake air and the amount of fuel supplied to the engine.

Abstract: An idling speed control device normally controlling the idling speed of the engine so that it becomes equal to a desired idling speed. At the time of acceleration, the lean time and the rich time of the air-fuel mixture are calculated during the lean-rich discriminating time, which is basically equal to a time of an occurrence of the lean time and the rich time when the air-fuel ratio is maintained at the stoichiometric air-fuel ratio at the time of acceleration. If the lean time becomes considerably longer than the rich time when the engine is started, the idling speed is increased.

Abstract: A fuel supply controller for an internal combustion engine includes an acceleration mode detector, an incremental fuel supply rate calculator, and a fuel supplier. The controller sets a smaller incremental fuel supply rate with increasing engine speed to prevent excessive fuel supply to the engine during acceleration. A fuel supply corrector, a correction inhibitor, and a correction inhibitor canceller are provided for improved acceleration performance regardless of the mode of acceleration. An acceleration mode discriminator and an incremental fuel rate supplier provide proper fuel control even with increasing acceleration. The controller can use first and second control maps for controlling fuel supply. A map discriminator provides for a smooth changeover between maps.

Abstract: The invention relates to a control systems for feedback control of the air/fuel ratio in an internal combustion engine, e.g., an automotive engine, which uses a three-way catalyst to purify the exhaust gas, by using an exhaust sensor to detect actual values of air/fuel ratio in the engine. The control system has the function of varying the target value of air/fuel ratio according to operating conditions of the engine. The target value becomes super-stoichiometric during steady-state operation of the engine and changes to a lower value optimum for the activities of the three-way catalyst, such as the stoichiometric value, under predetermined transient conditions of the engine. At the start of such a change in the target value, the control system functions so as to intentionally deviate the air/fuel ratio from the value optimum for the three-way catalyst in a direction away from the target value immediately before the change.

Abstract: The present invention is a method of firing fuel injectors for an engine of an automotive vehicle. The method includes the steps of determining whether injection timing for firing fuel injectors has changed from one predetermined state to another predetermined state of a distributor reference signal, firing the injectors for a predetermined time period and delivering a calculated amount of fuel for the one predetermined state if the injection timing has not changed. The method also includes determining whether a need for transition fuel has ended if the injection timing has changed and firing the fuel injectors for another predetermined time period and delivering a calculated amount of transition fuel at another predetermined state if the need for transition fuel has not ended.

Abstract: An apparatus to calculate the intake pipe pressure using the degree of throttle opening and the engine speed, to use this intake pipe pressure to calculate a current intake pipe pressure, and to determine a predicted value from this current intake pipe pressure and control fuel injection duration and/or spark timing. Because changes in the atmospheric pressure and changes in the air amount flowing through a bypass bypassing the throttle, etc., cause errors in the values predicted for the intake pipe pressure, there are irregularities in the exhaust emissions. The atmospheric pressure and the intake pipe pressure, etc., detected by a pressure sensor are used to correct the predicted value, and prevent irregularities and the like in exhaust emissions.

Abstract: In a fuel control system for an engine equipped with fuel injectors, a method where the fuel injector is fired to fuel its cylinder, relative to the cylinder's valve events, more than once per cycle if a throttle transient has occurred and caused the original firing of the fuel injector to be less than the fuel amount now required by the new engine operating conditions.

Abstract: An electronic control system for an internal combustion engine includes a plurality of first sensors for measuring a driver action taken in accordance with a driver's intent, a plurality of second sensors for measuring operating conditions of an engine, a plurality of actuators for controlling the engine, a unit for setting a target reference by selecting one among a plurality of target references for engine control, and a unit for manipulating the actuators responsive to the established target reference to control the engine.

Abstract: An air-fuel ratio control system for an internal combustion engine is disclosed. A basic fuel injection quantity is determined by using a cylinder pressure at a predetermined crank angle, and a signal provided by an intake air temperature sensor as parameters. A compensation fuel injection quantity for an accelerating mode or a decelerating mode is determined on the basis of a predetermined cylinder pressure variation corresponding to the variation of the output of a throttle opening sensor and an engine speed. The air-fuel ratio control system does not need an expensive air flow meter.

Abstract: An air-fuel ratio control system for use in an internal combustion engine is disclosed which comprises a supply unit equipped with a carburetor incorporating an acceleration pump for supplying fuel to the internal combustion engine and at least one duty-controlled solenoid valve adapted to controlling the air-fuel ratio; an operating condition detector for detecting the operating condition of the internal combustion engine; an acceleration controlled-variable decision unit for setting a predetermined acceleration controlled-variable being given to the solenoid valve during different acceleration control times corresponding to the operating condition or different acceleration; and a control variable decision unit for determining the controlled duty of the solenoid valve according to the data from the operating condition detecting unit and when the controlled variable is given by the acceleration controlled-variable decision unit at the time of acceleration, according to the acceleration control variable.

Abstract: An estimating execution for an inner surface portion adhesion fuel amount is practiced distinctlly and independently to an execution processing for a basic fuel injection amount. A correction coefficient to be multiplied by the basic fuel injection amount is calculated in accordance with the estimation execution for the inner wall surface portion adhesion fuel amount. The correction coefficient is multiplied by the basic fuel injection amount. Since the fuel injection amount is corrected in accordance with the estimated inner surface portion adhesion fuel amount, an air-fuel ratio during a transitional period of an engine can be maintained at a desirable value.

Abstract: A fuel injection control device in which the amount of fuel injected by the fuel injector is increased at the time of acceleration. Namely, at the time of acceleration, the lean time and the rich time of the air-fuel mixture are calculated during the lean-rich discriminating time, which is basically equal to a time of an occurence of the lean time and the rich time when the air-fuel ratio is maintained at the stoichiometric air-fuel ratio at the time of acceleration. When the lean time becomes considerably longer than the rich time, the amount of fuel injected by the fuel injector is further increased.

Abstract: A fuel injection control system for controlling the amount of fuel to be injected to an internal combustion engine. The fuel injection control system consists of a control unit arranged to calculate the fuel injection amount in accordance with a standard injection amount corrected with a transient correction amount. The transient correction amount is calculated in accordance with a difference value and a correction coefficient which is previously set in accordance with engine operating condition. The difference value is of between an equilibrium amount of adhering and floating fuel in steady state in an intake system and a predicted variable of amount of the adhering and floating fuel at a predetermined point of time.

Abstract: In a fuel supply control method including determining a cylinder at a suction stroke in a multiple cylinder internal combustion engine at each generation of a first predetermined crank angle position signal and injecting/supplying into a cylinder at a suction stroke a first amount at fuel which is computed by a first technique based on a sucked amount of air, A, and number of engine rotations, N, representing an engine load, a method comprises determining a cylinder at a suction stroke for asynchronous injection at each generation of a second crank angle position signal which is nearer to a top dead center of each cylinder than the first predetermined crank angle position signal; detecting a throttle valve opening for each predetermined time Ts and computing a throttle value opening variation .DELTA. .circleincircle.H ; and injecting/supplying, upon determining the variation .DELTA. .circleincircle.H as being greater than a predetermined value, a second amount of fuel corresponding to the variation .DELTA. .

Abstract: A multi-cylinder internal combustion engine is provided with a fuel injection system, which includes a plurality of fuel injection nozzles securely mounted in independent intake passages communicating with combustion chambers of respective cylinders, an air-flow sensor for detecting the amount of intake air to be led into each combustion chamber, a crank angle sensor and a cylinder discrimination sensor for detecting the present stroke timing of each cylinder, a speed sensor for detecting the engine speed and a control unit for outputting a signal to the fuel injection nozzles so that a predetermined amount of fuel may be injected to each cylinder at a predetermined timing on the basis of values detected by the respective sensors. The control unit calculates the injection timing of fuel to be injected into each cylinder so that the injection start timing may be altered in compliance with driving conditions of the engine.

Abstract: In a fuel supply control method of an automobile engine wherein a plurality of parameters representing an operating condition of the engine are measured, and a fuel supply quantity is determined based on the measured values so as to attain a target air-fuel ratio, an amount of air flowing into each cylinder in an n-th stroke (n is an arbitrary integer) is calculated for prediction by using the measured parameters in a stroke preceding the n-th stroke, and the fuel supply quantity is determined by the predicted value of the amount of air in the n-th stroke and a target value of the air-fuel ratio in the n-th stroke.

Abstract: In an internal combustion engine control system, an electronic circuit accepts a non-linear analog signal from a Mass Air Flow (MAF) sensor and converts it to a digital signal by means of a linear or non-linear analog to digital (A/D) converter. The digital signal is then processed by a two-dimensional look-up table which includes corrections for the MAF sensor non-linearity and additional corrections for non-linearity of the A/D converter. This linearized MAF signal is then integrated or averaged to provide air mass per engine event or average mass air flow during an event. This circuit is useful in obtaining better accuracy in fuel management systems that use MAF sensors, particularly if variable valve control is included as part of the control system. The look up table and integrator can be easily implemented in a digital signal processor or microcontroller.

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 fuel control apparatus for an internal combustion engine which comprises a pressure detecting means for detecting a pressure in a bypass air passage which bypasses a throttle valve in an air intake system for an internal combustion engine, a first estimating means for estimating a value corresponding to the effective cross-sectional area of the bypass air passage, a second estimating means for estimating a pressure in an intake air pipe of the air intake system on the basis of a pressure value detected by the pressure detecting means and an estimated value of effective cross-sectional area obtained by the first estimating means, and an operating means for calculating a fuel injection quantity on the basis of an estimated value of pressure in the intake air pipe which is obtained by the second estimating means.

Abstract: A fuel injection device for an automotive internal combustion engine is disclosed, which comprises two distinct acceleration state determining means, i.e., a rapid and a slow acceleration state judgement means, for determining the amount of the asynchronous augmentation of fuel. The rapid acceleration state judgement detects the rapid acceleration state by comparing with a first threshold level the increment of the throttle opening degree over each period of an A/D conversion timing signal; the slow acceleration judgement means, on the other hand, detects the slow acceleration state by comparing with a second threshold level the increment of, for example, the throttle opening degree signal over, for example, two successive periods of the same A/D conversion time signal. When the rapid acceleration state is detected, an asynchronous augmentation of fuel for the rapid acceleration is effected.

Abstract: A fuel injection control device in which the supply of fuel into the engine cylinder is stopped at the time of deceleration, and a rich time of the air-fuel mixture is calculated when the supply of fuel is stopped. If the rich time becomes relatively long, the accelerating increasing rate of the amount of fuel is increased, and if the rich time becomes relatively short, the accelerating increasing rate of the amount of fuel is reduced.

Abstract: A basic threshold value is calculated by averaging fluctuations of engine speed, and an acceleration threshold value which is higher than the basic threshold value is calculated. Surges existing in the fluctuation are compared with the basic threshold value and with the acceleration threshold value. The ignition timing of the engine is retarded by a predetermined initial retard angle when a first surge after beginning of acceleration of the engine is higher than the acceleration threshold value, and the ignition timing is retarded by retard angle which is smaller than the initial retard angle when each of second and subsequent surges is higher than the basic threshold value.

Abstract: A fuel supply control system for internal combustion engines with an air flow mounted in a intake manifold, a throttle valve opening sensor and a control unit, in which at quick acceleration the control unit generates a correction air flow quantity signal in accordance with the change of the output of the throttle valve opening sensor and corrects the output signal of the air flow sensor by the correction air flow quantity signal, whereby estimating real air flow quantity sucked into the engine cylinders.

Abstract: A fuel injection control device in which it is determined whether the air-fuel mixture is lean or rich at a predetermined crankangle during a lean-rich discriminating time at the time of acceleration. The lean-rich discriminating time is shortened as the degree of the acceleration becomes larger, and the times of being lean and the times of being rich within the lean-rich discriminating time are calculated. When the times of being lean are larger than the times of being rich, and the difference therebetween is larger than a predetermined value, the accelerating increasing rate of the amount of fuel fed into the engine cylinder is increased.

Abstract: An engine controller comprising a means for estimating an amount of the air flowing into the cylinder of the engine. The estimation means calculates the intake air amount mc(k+1) in the following equation determined from the physical model describing the law of conservation of mass for the intake air:mc(k+1)=.alpha..multidot.Q/.omega.+.beta..multidot.mc(k)where .alpha. and .beta. are constants, mc(k) is the last estimated value, Q is the flux of the detected air, and is the engine speed. The estimation is executed synchronously with the intake stroke so as to control the fuel injection amount synchronously with the intake stroke. To further improve the accuracy of the fuel injection even when the running condition of the engine changes after the estimation of the intake air amount, the fuel should be injected asynchronously with the intake stroke. We also disclose the engine controller that controls the amount of such an asynchronous injection.