Abstract: A method of controlling air-fuel ratio of a mixture supplied to an internal combustion engine in a feedback manner responsive to an output signal from an exhaust gas concentration sensor. The air-fuel ratio of the mixture is controlled to a desired value by means of proportional control and integral control. The proportional control is inhibited, when the value of the output signal has changed from a lean side to a rich side with respect to a predetermined reference value while the engine is operating in one of a predetermined high load condition and a predetermined high rotational speed condition.

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 output correction method for a proportional-output type O.sub.2 sensor including an oxygen concentration detecting element formed by an oxygen-pumping element and a cell element, each of the oxygen-pumping element and the cell element being composed of a wall of a solid electrolytic material having oxygen ion-conductivity, and a pair of electrodes having the wall interposed therebetween. The oxgen-pumping element is supplied with an output voltage corresponding to a difference between a voltage developed between the electrodes of the cell element and a predetermined reference voltage, and current flowing in the oxygen-pumping element is detected. A correction resistance supplies information indicative of a deviation of an air-fuel ratio detected by the sensor with respect to a predetermined reference air-fuel ratio. A correction value is determined on the basis of the information and the direction of flow of the current. The detected current is corrected by the use of the determined corrected value.

Abstract: An output control system for an internal combustion engine for an automotive vehicle having a variable capacity type compressor installed therein and driven by the engine, in which the output torque of the engine is increased by means of an engine output incremental value in response to operation of the compressor. Load torque produced by the compressor is detected through the piston stroke and discharge pressure of the compressor, and the engine output incremental value is set depending on the detected load torque. The engine output incremental value is also set depending on the engine rotation speed.

Abstract: A fuel supply control system for an internal combustion engine in which an accelerating fuel increment of fuel supplied to the engine is set in response to the detected change rate in the opening degree of the throttle valve. Further, the accelerating fuel increment is set in such a manner that it is smaller as the detected reduction gear ratio of the transmission is larger. Advantageously, the accelerating fuel increment is set to increase at a smaller rate as the above detected change increases within a region within which the change rate is smaller than a region in which the change rate is larger.

Abstract: A method of controlling supercharging pressure in an internal combustion engine wherein the supercharging pressure created by a supercharger is controlled based on a basic control amount determined in dependance on operating conditions of the engine. The basic control amount is corrected in response to the difference between an actual value of the supercharging pressure and a desired value thereof when the engine is in a feedback control region. The basic control amount is corrected in accordance with the rate of change of the supercharging pressure when the engine is in an operating condition immediately before the feedback control region. The supercharging pressure is controlled based upon a second basic control amount other than the first-mentioned basic control amount when the supercharging pressure is below a predetermined value determined by the engine rotational speed and the rate of change of supercharging pressure in the above operating condition.

Abstract: A fuel supply control system for an internal combustion engine, wherein when the engine is at idle, a correction value is determined based on a difference between a desired idling engine rotational speed and an actual engine rotational speed, and an amount of fuel to be supplied to the engine is corrected by the determined correction value. Correction value-changing means sets a rate of change in the correction value relative to a change in the difference to a greater value when the detecting means detects that the engine means is not engaged with the transmission of an automotive vehicle, and to a smaller value when the detecting means detects that the engine is engaged with the transmisison.

Abstract: A system for controlling the idling rotational speed of an internal combustion engine controls a control valve for adjusting the opening area of an intake air passage bypassing a throttle valve after cranking of the engine, by the use of control terms including a differential term which is based on a variation in the engine rotational speed and is set and held at zero before a predetermined time period elapses after completion of cranking of the engine.

Abstract: An air-fuel ratio control method for an internal combustion engine having an exhaust gas-ingredient concentration sensor provided in an exhaust system and generating an output proportional to the concentration of an ingredient in exhaust gases emitted from the engine. The air-fuel ratio of a mixture supplied to the engine is controlled to a desired air-fuel ratio corresponding to an operating condition in which the engine is operating, in a feedback manner responsive to the output of the sensor. Supply of fuel to the engine is interrupted while the engine is in a predetermined decelerating condition. The method comprises the steps of progressively decreasing the desired air-fuel ratio from a value larger than a value corresponding to the operating condition of the engine to the latter value after the engine leaves the predetermined decelerating condition, and controlling the air-fuel ratio of the mixture supplied to the engine to the progressively decreased air-fuel ratio in the feedback manner.

Abstract: A method of detecting failure of an exhaust gas component concentration sensor for detecting concentration of a component of exhaust gases from an internal combustion engine. The method comprises the steps of: (1) applying a predetermined voltage to the sensor, (2) determining whether or not a change in an output voltage from the sensor caused by the application of the predetermined voltage to the sensor is smaller than a predetermined value, and (3) deciding that the sensor is faulty when the change in the output voltage is smaller than the predetermined value. A device for sensing concentration of a component of exhaust gases from an internal combustion engine comprising an electric resistance member connected in series between an electric current supply source and one of a pair of electrodes provided on a solid electrolytic element.

Abstract: An electronically-controlled fuel injection system for internal combustion engines. When the engine is in an accelerating condition, an amount of fuel supplied to the engine is increased by means of an incremental value. It is discriminated whether or not a predetermined time period has elapsed from the time the rotational speed of the engine increased above a predetermined value, or from the time gear shifting was completed, while the engine is in the accelerating condition. The incremental value is limited to a predetermined upper limit if the former exceeds the latter before the lapse of the predetermined time period, whereby sudden increase in the engine rotational speed can be prevented.

Abstract: A method of determining the deterioration of an oxygen concentration sensor for an internal combustion engine. The oxygen concentration sensor includes at least one oxygen concentration sensor element having an oxygen-pumping element and a cell element each composed of a member of a solid electrolytic material having oxygen ion-conductivity, and a pair of electrodes having the member interposed therebetween, and a current-detecting resistance serially connected to the oxygen-pumping element to form a series circuit. A voltage having a magnitude corresponding to a difference between a voltage produced between the electrodes of the cell element and a predetermined reference voltage is applied to the series circuit, and pumping current is detected from a voltage developed across the current-detecting resistance.

Abstract: An air-fuel ratio control method for an internal combustion engine, wherein when the engine is in a feedback control region, a value of concentration of oxygen detected by the O.sub.2 sensor is compared with a predetermined reference value, and the air-fuel ratio of a mixture being supplied to the engine is controlled to a desired value in a feedback manner responsive to the comparison result. When the engine is in a predetermined high load operating region, the feedback control is interrrupted and an amount of fuel to be supplied to the engine is increased by a predetermined amount to thereby enrich the air-fuel ratio. The predetermined amount is increased when the engine is in the predetermined high load operating region and at the same time the detected oxygen concentration indicates that the air-fuel ratio is on a lean side with respect to the desired value.

Abstract: A method of controlling supercharging pressure in an internal combustion engine by means of a basic control amount dependent upon operating conditions of the engine. A change rate of the supercharging pressure is detected. When the supercharging pressure is in a transient state where it is increasing, the basic control means is corrected in response to the detected change rate of the supercharging pressure, in such a manner that the supercharging pressure increases at a predetermined rate.

Abstract: A method of controlling supercharging pressure in an internal combustion engine is disclosed. The supercharging pressure is controlled based on a basic control amount determined in dependence on operating conditions of the engine. When the transmission is in a lower speed position, the basic control amount is corrected so that the supercharging pressure is lower than a value assumed when the transmission is in a higher speed position. When the engine is in a feedback control mode, the basic control amount is corrected in response to the difference between the actual supercharging pressure and a desired value of same. The desired value of the supercharging pressure is set lower when the transmission is in the lower speed position than a value assumed when the transmission is in a higher speed position. When the transmission is in the lower speed position, the rising speed of the supercharging pressure in a transient states is set lower than a value assumed when the transmission is in a higher speed position.

Abstract: A method of controlling in a feedback manner the air-fuel ratio of an air-fuel mixture being supplied to an internal combustion engine of the type that vaporized fuel is supplied from a fuel supply system to an intake system thereof. The air-fuel ratio is controlled by the use of a correction value which varies in response to an output from an exhaust gas ingredient sensor, and the maximum or minimum value of which is limited to an upper or lower limit value. The pressure of the vaporized fuel in the fuel supply system is sensed, and at least one of the upper and lower limit values is set in accordance with the sensed pressure of the vaporized fuel. Further, the air-fuel ratio is controlled by the use of an average value of the correction value. The pressure of the vaporized fuel in the fuel supply system is sensed, and the calculation of the average value is inhibited when the sensed pressure of the vaporized fuel is higher than a predetermined value.

Abstract: An air-fuel ratio feedback control method for an internal combustion engine in which when the engine is operating in a feedback control region, the concentration of an ingredient in exhaust gases from the engine is detected by an exhaust gas ingredient concentration sensor arranged in the exhaust system of the engine and compared with a reference value, and the air-fuel ratio of an air-fuel mixture to be supplied to the engine is controlled to a desired value in a feedback manner responsive to the result of the comparison. Atmospheric pressure is detected, and the reference value is set to a value depending on the detected value of atmospheric pressure. The reference value is set to a higher value as the detected value of atmospheric pressure is lower. The reference value is set to a lower value when the engine is operating in an idling region than when the engine is operating in a region other than the idling region.

Abstract: An output correction method for an exhaust gas ingredient-concentration sensor for internal combustion engines. The sensor has two sensor elements having output characteristics different from each other. The sensor elements each produce an output proportional to the concentration of an ingredient in exhaust gases emitted from the engine. The sensor controls the air-fuel ratio of a mixture supplied to the engine to a desired air-fuel ratio by the use of an output from at least one of the sensor elements. First, it is determined whether or not the difference between the desired air-fuel ratio and an actual air-fuel ratio represented by the output of at least one of the sensor elements is smaller than a predetermined value. Then, an output value of one of the sensor elements is corrrected based on an output value of the other of the sensor elements when it is determined that the difference is smaller than the predetermined value.

Abstract: A method of determining the activation of an exhaust gas ingredient-concentration sensor for use in an internal combustion engine. The air-fuel ratio of a mixture is controlled in a feedback manner by the use of a coefficient varying with an output of the sensor during engine operation in an air-fuel ratio feedback control region. The activation of the sensor is determined based on the output of the sensor. When the engine has shifted from the air-fuel ratio feedback control region to a predetermined decelerating region, calculated is an average value of values of the coefficient obtained by the feedback control immediately before the shifting. The air-fuel ratio of the mixture is leaned by the use of the average value thus calculated. It is determined whether or not the sensor is activated when the air-fuel ratio has thus been leaned.