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 engine control system corrects an air-fuel ratio of an air and fuel mixture during feedback control in a feedback region of engine operating conditions and during a learning control in a learning region of engine operating conditions. A purge region of engine operating conditions, in which purging of fuel vapor into the engine is conducted, is defined so as to have a portion overlapping with the learning control region. The air-fuel learning and the fuel vapor purging are conducted alternately. A specific region of engine operating conditions is defined in the purge region for higher flow rates of intake air. The control system undergoes the air-fuel learning prior to the fuel vapor purge when engine operating conditions are in this specific region.

Abstract: A flexible fuel vehicle is a vehicle capable of operating on alcohol, gasoline, or any combination of these two fuels. Because of the unique properties of alcohol fuels, modifications to engine operating characteristics are required to compensate for the varying percentage of alcohol in the fuel. A method is provided for determining the percent alcohol content of the fuel in the fuel tank, utilizing the oxygen sensor feedback control loop to sense changes in air/fuel ratio and relay that information to the engine controller so that dependant variables can be adjusted accordingly. The method includes placing the fuel pump in the fuel tank along with a mixed fuel accumulator so that a known and slowly varying percentage of alcohol in the fuel is provided to the engine, especially during open loop operation.

Abstract: An air fuel ratio control system for an internal combustion engine having an electronic engine control module and an upstream and a downstream exhaust gas oxygen sensor positioned in the engine exhaust gas stream. A first feedback loop includes the upstream EGO sensor and an air fuel bias table. A second feedback loop includes a downstream EGO sensor and a trim signal to change the stored values in the air fuel bias table.

Abstract: A first O.sub.2 sensor is installed upstream, and a second O.sub.2 sensor downstream, of the catalyst converter in the exhaust passage of an engine. It is judged from the output of this first O.sub.2 sensor whether the air-fuel ratio (AFR) has changed beyond the theoretical AFR, and AFR feedback control is performed based on the judgment result. A correction value of an AFR feedback control coefficient is previously stored in each learning area in a memory corresponding to the engine running conditions, and the fuel injection amount supplied by the fuel injector is corrected based on this correction value.The correction value is updated by an updating amount corresponding to the magnitude of the difference between the output of the second O.sub.2 sensor and a value corresponding to the theoretical AFR. Undershoot or overshoot of the AFR is thereby prevented, and the AFR is rapidly brought within a desired range.

Abstract: An air/fuel ratio control method and system for an internal combustion engine employing first and second air/fuel ratio sensors, respectively upstream and downstream of a catalytic converter, sets and stores learnt correction values, by learning through an averaging process, for an air/fuel ratio correction value by a second air/fuel ratio sensor, stores a degree of progress of learning with respect to each learning, and modifies the learnt correction value with a modification ratio depending upon the degree of progress of learning. Accordingly, both a promotion of the learning and an enhancement of the accuracy of the learning can be achieved, and thus the emission control performance can be improved by progressively reducing an offset at the transition from an inactive state to an active state of the air/fuel ratio feedback control or at the transition of an engine driving range.

Abstract: A control unit for an internal combustion engine that compensates for variations in injection valve flow rate characteristics by detecting an operation status of the engine and then using this status information to calculate a supply air amount or supply fuel amount in accordance with the detected status. Exhaust gas constituents are detected and then used to correct the calculated supply air or supply fuel amount. The control unit compares the exhaust gas constituents with predetermined values and then uses a neural network to control the supply air amount or supply fuel amount to make any deviation between the exhaust gas constituents and the predetermined value approach zero.

Abstract: A control system (10) controls fuel injected into an internal combustion engine (14) having a fuel vapor recovery system (74) coupled to the air/fuel intake. To achieve stoichiometric combustion, delivery of liquid fuel is trimmed by a feedback variable (32) responsive to an exhaust gas oxygen sensor (26) and a learned value (40) representing quantity of recovered fuel vapor. Learning (40) is inhibited when an indication is provided of air/fuel operation rich of stoichiometry which is caused by factors other than vapor recovery.

Abstract: A digital control unit, in particular an ignition and/or injection control unit for motor vehicles, is provided. The control unit has a microcomputer (10) and a permanently connected main storage (12) containing control data and operating programs. This main storage unit (12) is designed as a read/write memory (RAM, EEPROM or the like). A control program that runs when the control unit is switched on is provided in an auxiliary storage (13) designed as a permanent storage (ROM, EPROM or the like). Based on a load instruction, the control program controls the loading of the main storage (12) from an external storage medium via an interface (21). The control program also automatically transfers the operating program access of the microcomputer (10) to the main storage (12). In this manner, software modifications can easily be subsequently implemented in the control unit when, for example, improvements or variations in program data or characteristic data are available and desired.

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 arrangement for lambda control operates on an internal combustion engine (11) comprising a catalytic converter (12) and a lambda probe (13.v) mounted in front of the catalytic converter and a lambda probe (13.h) mounted behind the catalytic converter. The arrangement integrates by means of an integration means (15) the difference between the actual lambda value measured by the rear probe and the lambda desired value to which controlling is to be effected. The integration value is used as control desired value for a means (16) for lambda control. This arrangement and the associated method make it possible to control to the actually wanted lambda desired value even if the front lambda probe carries out incorrect measurements, for example because of hydrocarbons in the exhaust gas in front of the catalytic converter or, in the case of continuous-action control, faulty linearization of the probe characteristic.

Abstract: An air-fuel ratio control device comprising an O.sub.2 sensor arranged in an exhaust passage, an air-fuel ratio feedback correction amount calculating unit for calculating an air-fuel ratio feedback correction amount in accordance with an output of the O.sub.

Abstract: An air-fuel ratio controlling apparatus carries out air-fuel ratio feedback control with the use of air-fuel ratio sensors disposed on the upsteam and downstream sides of a three-way catalytic converter. An air-fuel ratio feedback correction coefficient calculated based on an output value of the upstream air-fuel ratio sensor is corrected according to a correction quantity obtained based on an output value of the downstream air-fuel ratio sensor. This correction quantity is calculated according to a learned collective correction quantity uniformly applicable for a whole operation region, and learned regional correction quantites applicable for divided operation regions, respectively. When the learned collective correction quantity is corrected through addition, a portion added to the learned collective correction quantity is subtracted from each of the learned regional correction quantities.

Abstract: A system which monitors the performance of at least one HC sensor arranged in an exhaust passage of and internal combustion engine. According to a first aspect of the invention, a value of output from the at least one HC sensor is stored, which is assumed when the fuel supply to the engine is cut off, and a value of output from the at least one HC sensor is corrected by the stored value. According to a second aspect of the invention, the value of output from the at least one HC sensor assumed when the fuel supply to the engine is cut off is compared with a predetermined value, and if the former exceeds the latter, it is judged that there is abnormality in the at least one HC sensor.

Abstract: In an air-fuel ratio feedback system including a single air-fuel ratio sensor downstream of or within a three-way catalyst converter, a coarse-adjusting term AF.sub.c is calculated integrally in accordance with the output of the air-fuel ratio sensor, and an O.sub.2 storage term AF.sub.CCRO is calculated in accordance with an O.sub.2 storage amount of the three-way catalyst converter.

Abstract: This invention relates to a method of controlling the air-fuel ratio of an internal combustion engine having a main 0.sub.2 sensor and a subsidiary O.sub.2 sensor provided upstream and downstream, respectively, of a catalyst converter for detecting the oxygen concentration of the exhaust gas of the engine. The method comprises: feedback-controlling the air-fuel ratio of a mixture gas to be supplied to the engine to about a stoichiometric air-fuel ratio having the highest purification efficiency of the exhaust gas by adjusting the amount of fuel to be supplied by an injector in accordance with the output signal from the main O.sub.2 sensor; and also feedback-controlling more precisely the air-fuel ratio of the mixture gas to about the stoichiometric air-fuel ratio by adjusting the amount of fuel supply in accordance with the output signal of the subsidiary O.sub.2 sensor. The feedback control value set for adjusting the amount of fuel supply in accordance with the output signal of the subsidiary O.sub.

Abstract: A fuel blending ratio detecting method computes a control blending ratio on the basis of blending ratio information generated from a blending ratio sensor or air/fuel ratio information generated from an O.sub.2 sensor, and when the engine is stopped, the control blending ratio detected at that time is stored in a backup memory as a memory blending ratio. At the time of re-starting the engine, the memory blending ratio can be used as the control blending ratio B for a predetermined limited period.

Abstract: The rich or lean status of an air/fuel control system is determined according to the difference between the time period that the normalized air/fuel ratio is greater than an upper limit and the time period that the normalized air/fuel ratio is less than a lower limit in equal number of successive rich and lean cycles when in closed-loop fuel operation. The degree of rich or lean of the system is proportional to the time period difference. An adaptive learning control correction factor is incremented or decremented by an adaptive amount proportional to the time period difference.

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 method for lambda control, the lambda controller actual value for forming a control deviation is not only measured by a lambda probe having a jump response but in addition, the averaged lambda value is used as a lambda measurement actual lvalue which is compared to a lambda measurement desired value. The lambda measurement desired value is fixed in advance for different values of operating variables such that it corresponds to that lambda value for every operating condition for which an optimal toxic substance conversion results. If the lambda measurement actual value deviates from a pregiven value, then at least one control parameter for the two-position control is so changed that the desired value self adjusts thereafter. This method and an apparatus operating pursuant thereto permit the two-position control to be so controlled with respect to its characteristics in all operating conditions that the particular desired mean lambda value self adjusts for optimal toxic substance conversion.