Abstract: A method and apparatus are disclosed for measuring atmospheric pressure in conjunction with an air-fuel ratio sensor of the type comprising a concentration cell with atmospheric air and exhaust electrodes on opposite sides of a solid-state electrolyte having oxygen ion conductivity. During an atmospheric pressure measuring cycle, oxygen ions are pumped from the atmospheric air electrode to the exhaust electrode, in a quantity which is either predetermined at a fixed value, or is sufficient to bring the cell to an equilibrium state. Atmospheric pressure is then calculated from measured emf of the cell, using an experimentally derived functional relationship. In a second embodiment, ions are pumped until a predetermined change of the concentration cell emf is achieved, and atmospheric pressure is determined based on the amount of time required to achieve such change. The atmospheric pressure measuring mode is operated on a time shared basis with the air-fuel ration detection mode.

Abstract: This fuel injection control apparatus consists of a calculating device for calculating an air-fuel ratio correction factor FAF, a learning device for learning an air-fuel ratio learning factor KG in accordance with the deviation of FAF from the reference value, and a controller for controlling the amount of injected fuel in accordance with FAF and KG. When the start enrichment FASE and the warm-up enrichment FWL are added, KG is learned in accordance with the corrected deviation which is the deviation of FAF corrected by the correction factor f(FASE+FWL) which is concerned with FASE and FWL. The learning accuracy is improved because KG is learned at each region of FWL which is divided into plural regions in accordance with the engine driving conditions.

Abstract: An engine air/fuel control system is disclosed having one feedback correction loop generating a feedback variable by essentially integrating the output of an exhaust gas oxygen sensor. A second feedback loop adaptively learns a feedback correction from the difference between the feedback variable and its desired value such as unity. A range of authority for the total air/fuel controller is adaptively learned from the learned correction value to maximize the correction which may be applied by the feedback variable under all operating conditions.

Abstract: The invention relates to a learning control method for adjusting the composition of an operating mixture for an internal combustion engine. The method includes the steps of: detecting the actual value of the composition; forming a control variable as a function of the instantaneous deviation of the actual value from the desired value; logically coupling the control variable to a base value of an adjusting parameter of the composition and driving an actuator on the basis of the logically coupled value; and, learning of an additional intervention in the control loop from the performance of the control loop wherein the learning takes place at a speed which is at least dependent upon temperature.

Abstract: A method and an apparatus are provided for adapting air values from a substitute performance graph to currently prevailing variables of state of ambient air. The air values are used for controlling mixture preparation if pulsations of air occur in an intake tube of an internal combustion engine instead of using measured values supplied by an air meter. The air values are adapted by multiplying the air values by an adaptation factor. In one embodiment the adaptation factor is calculated by dividing a measured value supplied by the air meter in the intake tube of the internal combustion engine by an air value taken from the substitute performance graph and subjecting the adaptation factor to sliding averaging, at times when no pulsations are present; and using a lambda-control-average value as the adaptation factor and subjecting the adaptation factor to sliding averaging, at times when pulsations are present.

Abstract: Fuel-vapor evaporating from a fuel tank is led through a vapor pipe and absorbed in a charcoal canister. Fuel-vapor stored in the charcoal canister is supplied to an inlet pipe when a purge valve is opened when the engine is driven, because the pressure in the inlet pipe is low. Fuel-vapor is then burned as fuel in the engine. If the opening of the purge valve is suddenly increased at the start of the purge, the air fuel ratio control is disturbed. Therefore, the purge rate is gradually increased and the vapor concentration of the fuel-vapor purged from the charcoal canister is learned, and the change rate of the purge rate is made small because the air-fuel ratio control may be disturbed when the vapor concentration is not learned enough.

Abstract: Fuel-vapor evaporating from a fuel tank 13 is led through a vapor pipe 133 and absorbed in a charcoal canister 14. When a large amount of fuel is trapped in the charcoal canister, the learning of the basic air-fuel ratio correction factor executed in the control system 15 is interrupted in order to avoid faulty learning and the purging of fuel from the charcoal canister to the engine is continued in order to ensure sufficient fuel-purging. Only when a small amount of fuel is trapped in the charcoal canister, and the engine is driving in the region where the basic air-fuel ratio correction factor has not been learned, its learning is executed.

Abstract: An air/fuel control system for an internal combustion engine or the like delivers evaporated gas from the engine's fuel tank and adsorbed in a canister to an intake of the engine via a discharge route. A purge vacuum switching valve (VSV 16) disposed in the discharge route controls the rate at which the evaporated gas is delivered to the engine intake. Using a sensor, the air/fuel ratio of the engine intake is determined and the deviation of the detected air/fuel ratio from a target ratio calculated according to learned air/fuel ratio parameters is calculated. The density of the evaporated fuel stream is determined based on that deviation, and the VSV is driven based on the calculated evaporated gas density. If the air/fuel parameters are not learned within a predetermined time, the VSV is driven at a fixed rate. A drive signal to the engine's fuel injection system also may be corrected based on the calculated evaporated fuel density.

Abstract: An air-fuel control system for an internal combustion engine is provided in which air-fuel ratio control system a deviation effect due to an amount of evaporated fuel distributed to each cylinder group differing from cylinder group to cylinder group is eliminated when a deviation of air-fuel ratio due to aging of the engine has been learned. A difference value between the air-fuel correction factor and a value of a range of distribution deviation of the air-fuel ratio is obtained so that the difference value is used as the air-fuel correction factor. The difference value is obtained when the engine is determined to be in a purging operation by the first determining means, and when it is determined that learning of the air-fuel ratio correction factor is not completed. The difference value represents a true deviation of the air-fuel ratio due to aging of the engine parts.

Abstract: An air/fuel control system for an engine (28) provides an air/fuel indicating signal linearly related to average engine air/fuel operation from a two-state exhaust gas oxygen sensor (44). Fuel delivered to the engine is modulated with a periodic signal (144). Adaptive feedback control (steps 200-280) adaptively learns a desired amplitude for the periodic signal to generate the air/fuel indicating signal with desired sensitivity and operating range.

Abstract: Air-fuel ratio learning is only carried out at the time of high exhaust temperatures, and is inhibited when the exhaust temperature is less than or equal to a predetermined temperature. In the latter case, air-fuel ratio feedback correction coefficient .alpha. is correctingly set, taking a correction level indicated by an air-fuel ratio learned correction coefficient K learned at the time of high exhaust temperatures as a true correction requirement level.

Abstract: An air-fuel ratio control system, has an air-fuel ratio feedback control for feedback controlling an-air-fuel ratio of a mixture to be supplied into an engine based on a parameter detected from an exhaust gas discharged from the engine so as to set said air-fuel ratio to a target air-fuel ratio in an internal combustion engine. Vaporized fuel is supplied from a fuel tank to the engine. During an initial interval, the supply of vaporized fuel gradually increases. Learning an updating of a control value are accomplished in the feedback control based on a deviation of the air-fuel ratio from the target air-fuel ratio during supply of the vaporized fuel. Upon a resumption of supply of vaporized fuel, a learned value setting arrangement gradually changes the learned control value from zero (0) to a learned control value obtained during a preceding period of supply of vaporized fuel according to a gradually increasing amount of supply of vaporized fuel over a given interval.

Abstract: A purge amount is estimated by taking the change of purge amounts of a vapor from a canister side and a fuel tank side into consideration, an amount of fuel injection is corrected by the purge amount so estimated, and air-fuel ratio control is executed with a high level of accuracy. In an apparatus for correcting an amount of fuel injection of an internal combustion engine for purging the vapor directly evaporating from the fuel tank and the vapor emitted from the canister into an intake passage through a solenoid control valve and executing an air-fuel ratio control on the basis of the total purge flow amount, a correction amount of the amount of fuel injection on the tank side, which changes with the vapor supplied directly from the fuel tank into the intake passage through the control valve is calculated and a correction amount of fuel injection on the canister side which changes by the vapor supplied from the canister to the intake passage through the control valve is calculated.

Abstract: Air/fuel and ignition control of engine (28) are used to more rapidly heat-up a catalytic converter (52). A control system (8) generates a fuel command (100) for fuel delivery to the engine (28) based upon at least an amount of air inducted into the engine. The fuel command is offset by a predetermined amount in a lean direction during a period after engine start to shift the engine exhaust gas mixture towards a preselected air/fuel ratio lean of stoichiometry (106-122). In addition, the fuel command is corrected by a correction value so that the exhaust gas mixture is shifted ore closely to the preselected air/fuel ratio (126-140). Correction values are adaptively learned (300-324) during a portion of the warm-up period from a feedback signal derived from an exhaust gas oxygen sensor (44). Ignition timing and engine idle are also controlled (350-374) to further achieve more rapid warm-up of the catalytic converter (52).

Abstract: A learning control system for controlling an air fuel ratio an engine employs a slowly updated second learning control variable in addition to a normally updated first learning control variable in order to utilize the learning function sufficiently even when a deviation of the air fuel ratio exceeds the learning range of the first variable. The control system according to an illustrated embodiment of the invention identifies a current engine operating area among a plurality of such areas, in accordance with a sensed engine operating condition, obtains a value of the first learning variable corresponding to the identified operating area, and a value of the second learning variable, determines a learning quantity which is a sum of the first and second learning variables by using the obtained values, and uses this learning quantity for determining a desired fuel supply quantity. The second learning variable is updated slowly whereas the first learning variable is updated in a sensitive and speedy manner.

Abstract: An adaptive fuel control system and method directed for use in a motor vehicle powered by a fuel-injected engine and having a fuel tank and a fuel rail and which is operative to run on a plurality of fuels and fuel blends. The system includes a refueling mixer which acts as a fluid damper to slowly introduce new fuel into the fuel rail and correspondingly slow the rate at which new fuel composition is mixed with existing fuel. A stratification mixer is also utilized to re-mix components of blended fuels which may have separated at cold temperatures. An Exhaust Gas Oxygen sensor (EGO) monitors engine exhaust gases and generates a corresponding electrical signal when the air/fuel mixture of the fuel switches between rich and lean. Finally, an electronic control assembly communicates with the EGO and the fuel injectors to generate and store in memory an updatable extended adaptive fuel control table of air/fuel ratio multipliers for selected engine load/engine speed cells.

Abstract: An air/fuel control system (8) generates a fuel command (100) for fuel delivery to the engine (28) based upon at least an amount of air inducted into the engine. This fuel command is trimmed by a feedback variable derived (240-282) from an exhaust gas oxygen sensor (44) when feedback control is initiated. Feedback control is commenced when the peak-to-peak output of the sensor is less than a threshold value (122-128) while pumping current applied to a sensor electrode is modulated (122-128). Modulation is then removed but the pumping current is maintained to shift the sensor output to a preselected lean air/fuel ratio (128). Lean air/fuel feedback control continues until the converter is warmed (130-140).

Abstract: A method for controlling canister purge of an internal combustion engine is disclosed. Based on a change rate of an air-fuel ratio correction coefficient per unit duty, a canister loading ratio is assumed by looking up a map. Further based on the canister loading ratio, a correction amount to the purge control duty for controlling the purge amount from the canister is determine. It is therefore possible to control a canister purge in accordance with the canister loading amount, whereby an over-loading of the canister can be prevented even under a high evaporation condition such as at extremely high temperatures or high altitudes. A deviation of the air-fuel ratio caused by the canister purge can be calculated, whereby an improvement in startability, driveability and emissions can be achieved by updating air-fuel ratio learning values with new learning values excluding a deviation of the air-fuel ratio caused by the canister purge.

Abstract: An electronic engine control system incorporates an electronic fuel controller for adaptively altering the amount of fuel delivered to an internal combustion engine. The fuel controller detects the oxygen level contained in the engine's exhaust emissions along with the engine speed, or engine angular velocity, load and other engine operating parameters and varies the fuel delivery in accordance with the detected parameters. The change in fuel delivery is stored in a table contained in a memory. The information stored in the table is utilized by the fuel controller as an addend to a fuel delivery value calculated from the detected operating parameters.

Abstract: An improved adaptive transmission pressure control in which cumulative adaptive corrections are stored in a multi-cell memory array, the cells being associated with specified contiguous ranges of a vehicle operating parameter, such as engine throttle position. Periodically determined adaptive correction amounts are applied to a selected cell which includes the engine throttle setting measured at the initiation of the shift and to two or more cells associated with contiguous engine throttle ranges. In this way, a relatively large number of cells may be employed to minimize approximation errors, while maintaining a cell-to-cell continuum of pressure correction values. In operation, an electro-hydraulic pressure regulator is controlled as a combined function of a predefined pressure command obtained from a normal table look-up and a cumulative correction amount obtained from the memory array.

Abstract: Fuel injection controller is provided for an engine having a purge passage for purging fuel vapor from the fuel tank into the intake passage, a purge valve which opens and closes the purge passage and a mechanism for feedback correcting a fuel injection amount based on a detected air-fuel ratio, The controller learns a feedback correction amount when the purge valve opens or closes, stores and updates a learning value according to the variation of the correction amount. When the variation of the learning value has converged to within certain region, the controller clamps the learning value, and corrects the fuel injection amount during purge based on this clamped value. Air-fuel ratio errors due to purging can therefore be rapidly reduced.

Abstract: A method for controlling air-fuel ratio of an internal combustion engine with an adaptive learning control system. In recent years, as vaporized fuel restrictions are becoming stringent, a large quantity of vaporized fuel purged into an engine has a greater effect on an air-fuel ratio feedback control of an engine. Therefore, a portion originated from the vaporized fuel in the learning data is so much as being unable to be neglected. At an engine start, that portion hampers controlling an engine properly, resulting in adverse effects on emissions and startability.The present invention provides a method for eliminating such adverse effects by erasing the learning data originated from vaporized fuel exclusively before an engine start.

Abstract: An engine air/fuel control system includes an apparatus and method for adaptively setting an initialization period preceding closed loop fuel control. During the initialization period, fuel delivered to the engine is modulated by a periodic waveform. A high voltage signal associated with the high output state of an exhaust gas oxygen sensor and a low voltage signal associated with the low voltage state of the exhaust gas oxygen sensor are sampled. When the difference between these signals exceeds a preselected value, the initialization period is terminated and closed loop fuel control is actuated.

Abstract: An air-fuel ratio control apparatus constructed, in an engine of a type storing evaporated fuel generated in a fuel tank in a canister and thereafter drawing off the evaporated fuel to an intake side of an engine through a bleedoff passage, so as to inhibit renewal of an air-fuel ratio learning value when the evaporated fuel concentration is at a predetermined value or higher in case of learning and renewal of an air-fuel ratio in order to make feedback control of the air-fuel ratio of an air-fuel mixture supplied to the engine. In an apparatus which adsorbs evaporated fuel generated in a fuel tank in a canister and purges the evaporated fuel adsorbed in the canister to an intake side of an internal combustion engine together with air through a purge valve, an air-fuel ratio learning value is renewed in accordance with a deviation between an air-fuel ratio feedback FAF value detected by an oxygen sensor and a FAFSM value obtained by smoothing the FAF value with a large smoothing constant.

Abstract: The invention relates to a method for controlling a two-stroke internal-combustion engine with fuel injection in the low load range, in which the fuel supply to the combustion space is interrupted for a number of working strokes stored in a characteristic diagram which is a function of operating parameters. In this case, the stored characteristic diagram is adaptively corrected continuously by means of parameters which characterize the readiness to ignite or the ignition behavior of the internal-combustion engine.

Abstract: A control system which controls engine air/fuel ratio while providing a measurement of efficiency in the catalytic converter coupled to the engine exhaust. A test period is completed when counts in transitions of a feedback variable derived from an exhaust gas oxygen sensor positioned upstream of the converter have reached a preselected count for each of a plurality of inducted air flow ranges. Converter efficiency is determined during the test cycle by comparing an integration of the feedback variable, after band pass filtering and rectification, to an integration of a downstream exhaust gas oxygen sensor after its output is band pass filtered and rectified.

Abstract: In a method for assessing the operating capacity of a lambda control, which outputs regulated values FR which are to fluctuate about a desired regulated value FR.sub.- DES, which lambda control is assisted by an adaptation outputting adaptation values, the current value of a decision quantity, which indicates the averaged absolute value of deviation of the regulated value from the desired regulated value, is calculated continuously, then the current value is compared with a decision-quantity threshold value SW.sub.- EW, and the faulty signal is output when the current value exceeds the decision-quantity threshold value. It is therefore also possible to recognize those fails which occur only in part ranges of the total range in which an internal-combustion engine, in which the fuel supply is set by means of the lambda control, can be operated.

Abstract: An air-fuel ratio control system for an internal combustion engine comprises a catalytic converter disposed in an exhaust line of the engine. The converter has an oxygen storage effect. First and second oxygen sensors are disposed in the exhaust line at positions upstream and downstream of the converter respectively. Each sensor varies the output in accordance the oxygen concentration in the exhaust gas flowing in the exhaust line. A first device is employed for deriving an air-fuel ratio feedback correction value in accordance with the output from the first oxygen sensor. A second device is employed for changing the air-fuel ratio feedback correction value of the first device in accordance with the output from the second oxygen sensor. A third device is employed for controlling the quantity of fuel fed to the engine in accordance with the air-fuel ratio feedback correction value derived by the first device.

Abstract: An air-fuel ratio control apparatus of an internal combustion engine capable of learning and controlling an air-fuel ratio accurately both in idling and non-idling without being affected by concentration of evaporated fuel. Uniform deviation of an air-fuel ratio is detected before starting purging of the evaporated fuel (steps S133 to S137), air-fuel ratio learning values KGI.sub.0 to KGI.sub.7 and KGS.sub.0 to KGS.sub.7 are stored respectively so that the uniform deviation shows a predetermined value or lower both at idling time and at non-idling time (steps S138 to S142), and air-fuel learning values KG.sub.0 to KG.sub.7 in respective areas including idling are updated or renewed with a value obtained by leveling or averaging air-fuel ratio learning values KGI.sub.0 to KGI.sub.7 and KGS.sub.0 to KGS.sub.7 stored both at idling time and at non-idling time (step S145).

Abstract: A catalytic diagnostic apparatus for determining whether a catalyst of an internal combustion engine has deteriorated as disclosed. Air-fuel ratio sensors are placed at the upstream and downstream sides of the catalytic converter, and the output signal from the upstream air-fuel sensor is used to control the air-fuel mixture provided to the engine via the fuel injectors, in a conventional closed loop operation. Diagnosis of the condition of the catalytic converter is performed only when selected engine operating parameters fall within a predetermined diagnostic range. When the engine is operated in the diagnostic range, the condition of the catalytic converter is analyzed by calculating a deterioration index based on a comparison of the variation of the output signals from the upstream and downstream air-fuel ratio sensors.

Abstract: A method is provided for checking the function of a fuel composition sensor and for learning the percent alcohol content of a fuel used in a motor vehicle capable of operating on more than one type of fuel, as an alternative to a fuel composition sensor. The present invention improves the reliability of a motor vehicle utilizing a fuel composition sensor by allowing vehicle operation to continue uninterrupted, such as when a short or open condition exists within the sensor. The method first determines whether conditions are such that the percent alcohol content of a fuel should be "learned". If conditions are appropriated, then necessary engine operating conditions are first initialized. The oxygen sensor output signal is checked to determine whether the engine is operating too rich or lean. The value of percent alcohol content stored in the engine control unit's memory is modified in the direction of stoichiometric engine operation.

Abstract: A new two-cycle internal combustion engine configuration and control strategy in which the unburned hydrocarbon emissions are measured in the exhaust manifold during the scavenging process using a fast response air fuel sensor. The signal from the sensor is used to control the operation of a low pressure ratio blower and the inlet fuel and oil flow. In this way the inlet flow of fuel and air may be reduced which controls the short circuiting loss of fuel during the scavenging process and reduces unburned hydrocarbons in the exhaust gas.

Abstract: A control system which provides air/fuel feedback control while measuring catalytic converter efficiency. An efficiency test period is provided when the count in transitions of a signal related to an upstream exhaust gas oxygen sensor reaches a maximum count for a plurality of inducted airflow ranges. During the test period, three separate ratios indicating converter efficiency are provided. These ratios include: a ratio of downstream exhaust gas oxygen sensor total amplitude to a feedback variable derived from the upstream sensor; a ratio in frequency of transitions of the downstream sensor to frequency of the feedback variable; and a ratio of areas derived from the downstream sensor and feedback variable. When all three ratios indicate degraded converter efficiency, an overall indication is provided.

Abstract: An air-fuel ratio control system for an internal combustion engine equipped with a three-way catalytic converter. The air-fuel ratio control system is basically arranged to feedback-control air-fuel ratio of air-fuel mixture to be supplied to the engine to fall in a stoichiometric range by regulating a basic fuel supply amount in accordance with an air-fuel ratio feedback correction coefficient. The air-fuel ratio feedback correction coefficient is corrected with an integrated amount which is set to be increased after the measured value of a lapsed engine revolution number exceeds a decision standard. The lapsed engine revolution number is stored in the memory, and the average value of the lapsed engine revolution number is renewed with this stored lapsed engine revolution number in the memory.

Abstract: A control system which controls engine air/fuel ratio and provides a measurement of efficiency in the catalytic converter coupled to the engine exhaust. Fuel delivered to the engine is adjusted by a feedback variable which is generated by integrating an output of an upstream exhaust gas oxygen sensor and trimmed by the output of a downstream exhaust gas oxygen sensor. For each cycle of the feedback variable, peak amplitude of the downstream sensor output is determined and squared. Similarly, the peak amplitude of the feedback variable for each of its cycles is squared. An indicating ratio of the square of the sum of the squares derived from the downstream sensor to the square of the sum of the squares derived from the feedback variable indicates converter efficiency.

Abstract: A catalyst deterioration-detecting system is provided for an internal combustion engine having an oxygen concentration sensor arranged in an exhaust system downstream of a catalyst provided therein. An electronic control unit (ECU) controls the air-fuel ratio of a mixture supplied to the engine in response to an output from the oxygen concentration sensor. The ECU detects a value of an inversion period with which the output from the oxygen concentration sensor is inverted with respect to a predetermined reference value. Operating parameter sensors detect a value of at least one operating parameter of the engine related to a flow rate of the exhaust gases in the exhaust system. The ECU determines whether the catalyst is deteriorated, based on the detected value of the inversion period and the detected value of the at least one operating parameter. The ECU corrects the value of the inversion period in dependence on the detected value of the at least one operating parameter.

Abstract: A control system which controls engine air/fuel ratio and provides a measurement of efficiency in the catalytic converter coupled to the engine exhaust. At the end of each of a plurality of test periods, one of three selected ratios of output signals generated from exhaust gas oxygen sensors positioned downstream and upstream of a catalytic converter are sampled and the weighted average of the selected ratio over a plurality of test periods is determined. When the weighted average exceeds a reference ratio, an indication of converter efficiency is provided. Such an indication is also provided when the selected ratio exceeds the weighted average by a preselected amount, such as three standard deviations, for a preselected number of times. The weighted average is reset to the selected ratio when the selected ratio exceeds the weighted average by a preselected amount.

Abstract: An air-fuel ratio controller of an internal combustion engine for preventing that an air-fuel ratio in the beginning of the purging operation of evaporated fuel is excessive. Evaporated fuel produced within a fuel tank is absorbed in a canister and the evaporated fuel absorbed in the canister is purged to the air intake side of the internal combustion engine through a purge valve together with air. A concentration of the evaporated fuel is detected by an air-fuel ratio feedback value detected by an oxygen sensor and a fuel injection quantity is corrected to be reduced in accordance with the detected evaporated fuel concentration and the purge ratio. When the air-fuel ratio feedback value exceeds a predetermined value or an output of the oxygen sensor is rich during the purging operation, it is judged that detection of concentration is insufficient and the update value for detection of concentration is made larger than a usual value.

Abstract: A learning or updating function which corrects the feedback control correction factor is included in a dual O.sub.2 sensor type control system. Correction related data which is used to modify in response to the output of an upstream sensor or sensor section, is recorded at memory addresses which corresponding to the sub-sections of an engine operation map. When the output of the upstream sensor changes, a sub-region in which the engine operation fell a time .tau. earlier or in which the engine operation has continuously fallen for the time .tau., is selected and the correction related data which is recorded at the corresponding address, read out, updated based in the output of the second sensor or sensor section and re-recorded at the same address.

Abstract: In an air-fuel ratio control system for an internal combustion engine, an output from a first air-fuel ratio sensor arranged upstream of a three-way catalyst mounted across an exhaust passage of the engine is compared with a reference value during feedback control of the air-fuel ratio. The reference value is controlled based on an output from a second air-fuel ratio sensor arranged downstream of the three-way catalyst. The reference value is changed in dependence on the engine load detected.

Abstract: When engine operation falls in a predetermined zone wherein it is necessary to attenuate engine surging or the like type of engine operating phenomenon, and wherein mapped adaptive update value data is required to exhibit a different resolution to the adaptive update value data which is contained in the remainder of the map not included in the predetermined zone, the operation of the engine in the predetermined zone is detected and an indication of the same set. While the indication is set, updating of the mapped data which corresponds to the predetermined operational zone, is inhibited. In some embodiments mapped data which corresponds to the predetermined operational zone is set in a separate memory section and updated in a manner different from the manner in which the data which does not correspond to the special zone, is updated.

Abstract: An air-fuel ratio control device for an internal combustion engine, in which a first exhaust sensor is disposed at an exhaust passage of an internal combustion engine on an upstream side of a catalytic member which is disposed at the exhaust passage, and a second exhaust sensor is disposed at the exhaust passage on a downstream side of the catalytic member, with the air-fuel ratio being feedback-controlled by a control system in accordance with detection signals from the front and rear exhaust sensors.

Abstract: A learning or updating function which corrects the feedback control correction factor is included in a dual O.sub.2 sensor type control system. Correction related data which is used to modify in response to the output of an upstream sensor or sensor section, is recorded at memory addresses which corresponding to the sub-sections of an engine operation map. When the output of the upstream sensor changes, a sub-region in which the engine operation fell a time .tau. earlier or in which the engine operation has continuously fallen for the time .tau., is selected and the correction related data which is recorded at the corresponding address, read out, updated based in the output of the second sensor or sensor section and re-recorded at the same address.

Abstract: This invention relates to an air-fuel ratio control system for an engine which can continuously detect the air-fuel ratio of the air-fuel mixture supplied to the engine using an air-fuel ratio sensor within a wide range including the theoretical air-fuel ratio, and can then, based on the sensor output, perform feedback correction of the air-fuel ratio to the theoretical air-fuel ratio or to another air-fuel ratio. The deterioration of the air-fuel ratio sensor is judged based on the difference between the feedback correction coefficient when feedback control is performed to the theoretical air-fuel ratio, and the feedback correction coefficient when it is performed to another air-fuel ratio. Deterioration of the sensor is thereby detected completely separate from scatter or deterioration of performance of the fuel injector or other components.

Abstract: In a lean burn control system for an internal combustion engine, when surging in the engine is caused due to lowering of an engine lean limit, a first correction circuit decreases a target air-fuel ratio irrespective of whether the system is operated under an open loop control or a feedback control. On the other hand, when the surging is caused due to variation in output characteristic of an air-fuel ratio monitoring sensor, a second correction circuit decreases the target air-fuel ratio only when the system is operated under the feedback control. Accordingly, the target air-fuel ratio as corrected by the first correction circuit is used in the open loop control, while the target air-fuel ratio as corrected by the first and second correction circuits is used in the feedback control.

Abstract: An engine air-fuel ratio control unit is so constructed that, whenever any abnormal operation is detected in one of O.sub.2 sensors, the control unit makes corrections of a fuel amount injected from an injector on the basis of the output information from the other O.sub.2 sensor performing its normal operation and learned values obtained from both of the O.sub.2 sensors when both performed their normal operations.

Abstract: In a fuel blending ratio detecting method, a first blending ratio of the methanol in the fuel supplied to an internal combustion engine is detected by a blending ratio sensor; an air/fuel ratio feedback compensation coefficient computed on the basis of an output of an O.sub.2 sensor is used to compute a feedback learned value, and the current blending ratio compensation coefficient is multiplied by this value to compute the next blending ratio compensation coefficient so as to obtain a second blending ratio; the current blending ratio compensation coefficient is multiplied by a peak mean value of the computed feedback compensation coefficient to compute the next blending ratio compensation coefficient so as to obtain a third blending ratio; and the first, second or third blending ratio is selected according to the operating conditions of the internal combustion engine.

Abstract: An exhaust purification apparatus for an engine uses a catalytic converter provided in an exhaust system of the engine. First and second exhaust sensors are provided on upstream and downstream sides, respectively, of the catalyst converter in the exhaust system. Detected values from the first and second exhaust sensors are used for feed back control of air fuel ratio and judging deterioration of the catalyst of the catalytic converter, respectively. A control constant of the air fuel ratio of the feed back control is changed so that the second exhaust sensor detects in accordance with a condition of the catalyst.

Abstract: In an abnormality detecting device and method for an air-fuel ratio control system of an internal combustion engine, first discriminating whether a renewing number NLR of grids in a map of air-fuel ratio learning control is larger than a set value or not. If the number is larger than the set value, the difference between the number and previously renewed learning values is calculated. Then, judging whether the difference is larger than a predetermined value or not. If the difference is larger than the predetermined value, it is judged that an abnormality occurs in an intake air measurement system or a fuel injection system of an air-fuel ratio control system. Accordingly, the abnormality in the systems is distinguished from the deterioration due to normal aging.

Abstract: A system and method for learning and controlling an air/fuel mixture ratio for an internal combustion engine are disclosed which can achieve the compatibility of both learning convergence characteristic and accuracy of learning and which can prevent a stepwise change in correction coefficients to a basic fuel supply quantity when the present engine driving condition makes the present one of the driving conditions to the other one of the driving conditions. In a preferred embodiment of the air/fuel mixture ratio learning and controlling system, a plurality of learning maps in which the whole driving region is divided into 16 regions and is divided into 258 regions. The learnings of the air/fuel mixture ratio learning correction coefficients KBLRC1 for the 16 driving regions on the first learning map are followed by those of the other air/fuel mixture ratio learning correction coefficients KBLRC2 for the 256 driving regions on the second learning map.