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.

Abstract: A cylinder pressure detecting system includes a plurality of pressure sensors, each of which is provided for monitoring pressure in one of plurality of cylinders. The system performs data sampling of detection values produced by one of the pressure sensors corresponding to a cylinder in an intake stroke, and compares each of the sampled detection values and a predetermined reference minimum value to respectively set differences therebetween as offset correction values. These processes are performed for the respective cylinders. The detection values of the pressure sensors for the respective cylinders are corrected on the basis of the offset correction values so that the detection values detected by the respective pressure sensors coincide with each other.

Abstract: An apparatus for controlling the idling speed of an internal combustion engine. The apparatus comprises sensors for producing electrical signals indicative of sensed engine operating conditions including a sensed amount of air permitted to enter the engine. A control unit is coupled to the sensors for providing a feedback control to correct the amount of air permitted to enter the engine so as to maintain the engine idling speed at a target value when the engine is idling. The control unit calculates a difference of the sensed air amount from a reference value and corrects the target engine speed based upon the calculated difference.

Abstract: A development computer or first computer provided with a program development-supporting tool for checking an operation of a new control program written by a high-level language is disposed independently from a computer to be developed or second computer. Control based on a new control program written in a high-level language for the computer to be developed or second computer is executed by outputting the result of processing of the new control program by the development computer into the computer to be developed or second computer.

Abstract: A system for learning and controlling the air-fuel ratio of each of divided regions of an operating range of an engine employs a plurality of learning maps in which the engine operating range is divided into regions of different sizes, and these regions are learned in descending order of their sizes. This system improves the convergence of the learning as well as the accuracy of a correction of an air-fuel ratio for each engine operating condition.

Abstract: An air/fuel ratio feedback control system for an internal combustion engine sets an air/fuel ratio feedback correction coefficient on the basis of an air/fuel ratio for an air/fuel mixture introduced into a combustion chamber of the engine, to cause the air/fuel ratio to approach a set point thereof. The correction coefficient consists of a rich control proportional component P.sub.R, a lean control proportional component P.sub.L and an integral component I. When the air/fuel ratio set by the feedback control system deviates from an initial set point (the stoichiometric value) due to deterioration of an oxygen sensor for detecting the air/fuel ratio, the feedback control system compensates for the deviation to cause the air/fuel ratio to approach the initial set point, by varying a ratio of the rich control proportional component P.sub.R to the lean control proportional component P.sub.

Abstract: An apparatus for controllably sucking intake air into each cylinder of an internal combustion engine and method for controlling the intake air quantity of the internal combustion engine are disclosed in which, in an intake air passage, a first throttle valve associated with an acceleration element (accelerator pedal) is installed in a portion of the intake air passage located upstream of an intake manifold and a plurality of second throttle valves are installed in intake ports branched from the intake manifold whose opening angle is controlled by means of an actuator in response to a control signal input thereto. In addition, a bypass passage is connected between the intake air passage upstream of the first throttle valve and exits of the intake ports downstream of the second throttle valves to provide a swirl stream of the intake air sucked into each combustion chamber and a bypass intake air quantity control valve is installed in the bypass passage.

Abstract: In a steady operating condition of an engine, the fuel supply quantity is changed compulsorily and step-by-step, and in compliance with changing conditions of the fuel quantity sucked into cylinders after such correction of the fuel supply quantity, a fuel adhesion ratio and an evaporation ratio as the decisive parameters for a wall flow quantity of fuel are learned separately in each operational region, and using the learned results the fuel supply quantity in transitional operation is corrected.

Abstract: A discriminating value approximately corresponding to the amount of a change in mean effective pressure is calculated on the basis of the revolution period of an internal combustion engine, and a cause for the vibration of the vehicle and conditions in driving on a rugged road are indirectly detected from a misfire-originated change in engine torque. The natural frequency of the suspension of the vehicle with the internal combustion engine mounted thereon is adjusted based on the result of the detection, thereby automatically preventing comfortable riding from being deteriorated by a misfire-originated change in torque or by a drive on a rugged road.

Abstract: Only an air-fuel ratio of one specific cylinder is forcibly shifted by the correction of the fuel supply quantity, and the fuel supply characteristic error rate of fuel supply means of this one specific cylinder, where the air-fuel ratio is forcibly shifted is detected based on whether or not the influence of this shifting of the air-fuel ratio is manifested on the air-fuel ratio feedback correction value set, based on the average air-fuel ratio in respective cylinders, as expected. Correction values of the fuel supply quantity are set separately for respective cylinders, based on the fuel supply characteristic error rates thus determined separately for respective cylinders.

Abstract: In a fuel supply control system of an internal combustion engine having a function of feedback-controlling the air-fuel ratio, dispersions of the fuel supply characteristics in respective cylinders are corrected by changes of the air-fuel ratio by the correction of the fuel supply quantity. Factors causing the deviations of the air-fuel ratio are independently compensated by learning the correction value for correcting the fuel supply quantity only at a certain ratio and the correction value for correcting the fuel supply quantity only by a certain quantity so that these correction values are commonly fit for at least two different driving conditions.

Abstract: A value approximately corresponding to the amount of a change in mean effective pressure calculated on the basis of the revolution period of an engine is used for discrimination of a misfire. In detecting a misfired cylinder by comparing this misfire discriminating value with a slice level, a misfire detection at the coasting time is avoided. Further, a misfire discriminating value corresponding to a misfired cylinder is specified on the basis of a predetermined varying pattern of the discriminating value. The slice level is set to the proper value in accordance with this discriminating value.

Abstract: Disclosed are a process and apparatus for learning and controlling the air/fuel ratio in an internal combustion engine, in which a feedback correction value for correcting a basic fuel supply quantity to bring the air/fuel ratio of an air/fuel mixture sucked in the engine close to the target air/fuel ratio is set and a learning correction value for each of driving regions is learned so as to reduce the deviation of the feedback correction value from the target convergent value, and in this control of learning and correcting the air/fuel ratio, the target convergent value is variably set based on engine-driving conditions and the like so that the basic air/fuel ratio obtained without feedback correction can be optionally changed.

Abstract: A system and method for controlling an air/fuel mixture ratio of an air mixture fuel sucked into an internal combustion engine are disclosed in which an operating variable (PL, PR) of an air/fuel mixture ratio feedback correction coefficient (LAMBDA) is controlled so as to compensate for the deviation of the air/fuel mixture ratio (an average air/fuel mixture ratio) from a target air/fuel mixture ratio (stoichiometric air/fuel mixture ratio) according to an output characteristic variation of an oxygen sensor installed in an exhaust passage, the oxygen sensor outputting a voltage according to the air/fuel mixture ratio. A degree of deterioration of the oxygen sensor, i.e.

Abstract: A system for identifying a misfired cylinder of a multiple cylinder internal combustion engine is provided. The system comprises a sensor which monitors revolutional cycles of cylinders respectively to determine a parameter associated with a variation in an average effective pressure of the cylinder in a preselected relation to the revolutional cycles. When the parameter is less than a preselected level, the system corrects the parameter by a correction factor to provide a second parameter in order to prevent reduction in the average effective pressure due to wavering of engine speed after misfire occurs from causing erroneously detection of the misfire cylinder. The system then compares the second parameter with a slice level to detect occurrence of misfire and identifies the misfired cylinder.

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: In a fuel supply control apparatus constructed so that a fuel supply quantity is feedback-controlled to bring a detected value of an air-fuel ratio of an air-fuel mixture sucked in an engine to a target air-fuel ratio, a disorder of air-fuel ratio-detecting means is diagnosed based on a change of the balance of the response characteristic of the air-fuel ratio-detecting means in both the change directions of the air-fuel ratio, a change of an output value of the air-fuel ratio-detecting means or a change of the frequency of the feedback control.

Abstract: A method for detecting an intake pressure in an internal combustion engine which comprises detecting the intake pressure in the engine and at least one engine driving condition, variably setting a sampling period of the intake pressure to a sampling period, according to the engine driving condition, which is substantially different from a pulsation period of the intake pressure, sampling processing the intake pressure according to the sampling period set to set the value obtained by the sampling processing as a final detected value of the intake pressure, whereby the reliable sampling of the intake pressure is performed even if the intake pressure is pulsated.

Abstract: When there is observed a tendency that the proportion of the correction by an air-fuel ratio correction value for the feedback control of an air-fuel ratio in an air-fuel mixture sucked into an engine to a target air-fuel ratio is increased in the air-fuel ratio-enriching direction in a region of a smaller sucked air flow quantity, it is judged that the leakage of air into a suction system of the engine occurs. The quantity of the correction of the sucked air flow quantity corresponding to the quantity of leaking air is set based on the relation between the air-fuel ratio correction value and the corresponding sucked air flow quantity, and the detection value of an air flow meter is corrected based on this correction quantity.

Abstract: A method and apparatus for detecting an intake air state quantity in an internal combustion engine, where a detected value of an intake air state quantity participating in the quantity of air sucked in the engine, are dislosed. The method and apparatus are constructed so that a random number is generated, the frequency time of the above-mentioned sampling is variably set based on this random number, and the sampling frequency of the detected value of the intake air state quantity is randomly changed.