Abstract: A control system for an internal combustion engine is disclosed. The engine has an exhaust gas recirculation device which includes an exhaust gas recirculation passage for recirculating exhaust gases from the engine to an intake system of the engine, and an exhaust gas recirculation control valve provided in the exhaust gas recirculation passage, for controlling a flow rate of the exhaust gases. An air-fuel ratio control amount is calculated based on an output of the air-fuel ratio sensor provided in the exhaust system of the engine. The air-fuel ratio of the air-fuel mixture supplied to the engine is controlled with the air-fuel ratio control amount. A failure of the exhaust gas recirculation device is determined based on a changing component of the air-fuel ratio control amount when changing an opening of the exhaust gas recirculation control valve in a predetermined cycle.

Abstract: An engine control device is configured to prevent a rotational speed of a vehicle engine from becoming abnormally low during deceleration due to an abnormal air-fuel ratio. When conditions for feedback control of engine idle speed are not satisfied and self diagnosis results of the air-fuel ratio control system are normal, the control device determines if the air-fuel ratio is in an abnormally lean state. The control device then determines if the abnormally lean air-fuel ratio state has continued without interruption for a prescribed period or longer. If so, the control device calculates an air-fuel ratio abnormality compensation quantity, e.g., adds an air-fuel ratio abnormality compensation value to an idle compensation air quantity, to increase the intake air quantity and compensate for the engine torque deficiency resulting from the lean air-fuel ratio state.

Abstract: A fault detecting apparatus for a gas concentration sensor is provided. The apparatus includes a storage device and a fault detecting circuit. The storage device stores therein fault detectable conditions in which preselected different types of faults of the gas concentration sensor are allowed to be detected, respectively. The fault detecting circuit works to detect a selected one of the faults stored in said storage device. When one of the fault detectable conditions is encountered during operation of the gas concentration sensor, the fault detecting circuit initiates detection of a corresponding one of the faults based on an output of the gas concentration sensor, thereby enabling the fault detecting circuit to identify the type of one of the faults to be detected correctly.

Abstract: A deterioration determining apparatus and a deterioration determining method are applied to an engine in which a feedback control of an air-fuel ratio is performed by calculating an air-fuel ratio correction coefficient based on an output of an oxygen sensor, and response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor is set so as to be variable. In the deterioration determining apparatus and the deterioration determining method, a deterioration determining value concerning a determination as to whether the oxygen sensor has deteriorated is set so as to be variable according to the set response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor, and the determination as to whether the oxygen sensor has deteriorated is made based on an inversion cycle of the output of the oxygen sensor and the deterioration determining value.

Abstract: An air-fuel ratio detected by an air-fuel ratio sensor is periodically varied by executing a PI control. During the PI control, a time period in which the detected air-fuel ratio passes through a predetermined rich-side range is defined as a rich-side time constant, and a time period in which the detected air fuel ratio passes through a predetermined lean-side range is defined as a lean-side time constant. A rich-side time delay represents a time period in which an air-fuel correction amount is increasingly corrected to exceed a rich-side threshold, and a lean-side time delay represents a time period in which the air-fuel correction amount is decreasingly corrected to exceed a lean-side threshold. These time constants and time delays are compared with a determining value to diagnose degradation of an air-fuel ratio sensor.

Abstract: A deterioration failure diagnostic apparatus is provided for diagnosing an exhaust gas sensor disposed in an exhaust passage of an engine. The apparatus has a unit for generating a detecting signal and multiplying the generated signal to a first basic fuel injection amount to produce a second fuel injection amount. The apparatus includes a unit for calculating a feedback representative value based on feedback correction coefficients and multiplying the feedback representative value to the second fuel injection amount to produce a final fuel injection amount to be input to the engine. The apparatus includes a unit for extracting a frequency response corresponding to the detecting signal from an output of the exhaust gas sensor of the engine, the output being responsive to the calculated final fuel injection amount. A condition of the exhaust gas sensor is determined based on the extracted frequency response.

Abstract: A pressure sensor device of an internal combustion engine includes: a pressure sensor detecting a pressure in an intake pipe of an internal combustion engine, a pressure sensor failure determination device determining a failure of the pressure sensor, an idle determination device detecting that an opening of a throttle adjusting an air quantity supplied to the internal combustion engine is in an idle position, and a pressure sensor output value control device limiting an output value from the pressure sensor for use in a fuel injection quantity control of the internal combustion engine to be not more than a predetermined value when the throttle opening is determined by the idle determination device to be in the idle position and when the pressure sensor is not determined as being in failure by the pressure sensor failure determination device. This pressure sensor device prevents the over-rich of fuel injection quantity.

Abstract: In a diagnosing process in which a target air-fuel ratio in an air-fuel ratio feedback control is forcibly changed, and based on a response time of a detection signal from an air-fuel ratio sensor to the change, a response characteristic of the air-fuel ratio sensor is diagnosed. When the diagnosis is finished, an air-fuel ratio feedback control signal is returned stepwise to a value immediately before the starting of diagnosis.

Abstract: In a low rotation speed and low load operation region of an internal combustion engine, the heating of an air-fuel ratio sensor by a heater is stopped, and also an air-fuel ratio feedback control is stopped, and just after the heating of the air-fuel ratio sensor by the heater and the air-fuel ratio feedback control are started, a smoothing degree of a detection signal of the air-fuel ratio sensor is set to be small, to perform the air-fuel ratio feedback control based on the smoothed detection signal.

Abstract: A deterioration failure diagnostic apparatus for an exhaust gas sensor has a higher detection precision and a wider detection range against the deterioration failure of the exhaust gas sensor. An exhaust gas sensor is disposed in an exhaust gas pipe of an internal-combustion engine for producing an output corresponding to components of exhaust gas of the engine. The apparatus has a device for producing a detecting signal, which is multiplied to a basic fuel injection amount used at a normal operation to produce a fuel injection amount to be used for determining a condition of the exhaust gas sensor. The apparatus includes a device for extracting a frequency response corresponding to the detecting signal from an output of the exhaust gas sensor. The output is in response to the calculated fuel injection amount. The condition of the exhaust gas sensor is determined based on the extracted frequency response.

Abstract: An engine control system and method for a displacement on demand internal combustion engine includes a throttle preload signal generator that outputs a throttle preload area signal having a base portion and ramp out portion. A combining circuit combines the throttle preload area signal with a current throttle area signal to generate a throttle preload difference signal that adjusts throttle area to smooth transitions during at cylinder deactivation. The engine control system smoothes the transition between activated and inactivated modes by increasing throttle area and manifold pressure when transitioning between activated and deactivated modes.

Abstract: The air-fuel ratio computing apparatus includes a linear air-fuel ratio sensor for measuring an air-fuel ratio of exhaust gas and an electronic control unit for repeatedly performing filter processing on the air-fuel ratio, using a formula Vf(n)=(1?G)×Vf(n?1)+G×V(n). In a case where a temperature of the sensor is low, the unit cuts off a pump current to the sensor, performs the filter processing with the filter gain G set to a large value, and transforms a computed value from the filter processing into a theoretical air-fuel ratio voltage and in a case where the temperature of the sensor rises to or above a predetermined temperature, the unit performs the filter processing with a filter gain G set to a small value, and computes an air-fuel ratio from the difference between a computed value from the filter processing and the theoretical air-fuel ratio voltage.

Abstract: An engine control system has a self-diagnosis function of an exhaust system. The self-diagnosis function includes a first mode for detecting a failure or abnormality of the exhaust system as a whole, and a second mode for determining and locating a specific failed component in the exhaust system. The first mode is executed during the engine is operated under a normal condition. Therefore it is possible to detect the failure of the exhaust system without lowering a drive performance or increasing emissions. In case of detecting any failure in the first mode, the second mode is activated in response to a command signal that can be entered via a service tool. In the second mode, the engine is operated in order to determine the failed component. In the second mode, determining the failed component takes priority over keeping the drive performance or reducing emissions.

Abstract: An emission control system has a catalyst and a sensor responding to a component of exhaust gas. In order to speed warming up the catalyst, the emission control system increases the amount of heat dissipated by exhaust gas. A diagnosis of the emission control system is carried out by determining whether the amount of heat dissipated by exhaust gas is sufficient or insufficient. The amount of heat dissipated by exhaust gas is represented by the length of time to an activated state of the sensor. In the diagnosis, the amount of heat generated by a heater provided in the sensor is taken into consideration.

Abstract: A vehicle exhaust system includes a catalytic converter and an outlet sensor. The outlet sensor generates a sensor signal based on an oxygen level of exhaust gases exiting the catalytic converter. A controller communicates with an engine and the outlet sensor, and monitors the sensor signal during a predetermined period of engine operation. The controller commands an intrusive catalyst monitor test in a default order if the outlet sensor signal transitions through both thresholds during a predetermined period. The controller performs an intrusive outlet sensor test during cruise operation of the engine if the signal fails to transition through both thresholds during the catalyst monitor test.

Abstract: A control apparatus is provided for eliminating a step in a control input before and after switching between control processing based on one modulation algorithm selected from a ? modulation algorithm, a ?? modulation algorithm, and a ?? modulation algorithm and control processing based on a response specified control algorithm to avoid a sudden change in the output of a controlled object in the event of the switching.

Abstract: A failure diagnosis device for an O2 sensor includes an O2 sensor; a heater driving unit driving a heater heating the O2 sensor; and a diagnosis unit controlling the heater driving unit heating the heater, and diagnosing O2 sensor failure after a given amount of time based on an O2 sensor activation status determination using O2 sensor outputs. The diagnosis unit includes a heater controlling unit controlling the heater driving unit; a time measuring unit measuring time that electric current is supplied to the heater, and time used in determining sensor abnormality; an activation status determining unit determining air/fuel ratio changes from a lean to rich state, or from a rich to lean state based on the O2 sensor output; and a failure determining unit determining sensor abnormality based on outputs from the time measuring unit and the activation status determining unit, thereby diagnosing O2 sensor failure without engine operation.

Abstract: In a constitution for feedback controlling an air-fuel ratio using an oxygen concentration detector in which a detection signal thereof has a linearity to the air-fuel ratio within a predetermined air-fuel ratio range inclusive of a stoichiometric air-fuel ratio, when the detection signal from the oxygen concentration detector is outside a region indicating the linearity, a change in air-fuel ratio feedback control signal is limited to be smaller than that when the detection signal from the oxygen concentration detector is within the region indicating the linearity.

Abstract: The invention relates to a method for monitoring the functioning of an NOx sensor, which is arranged in an exhaust gas channel of an internal combustion engine and is located downstream from an NOx storage catalytic converter. The aim of the invention is to detect the faulty functioning of the NOx sensor in a simple manner in order to be able to take appropriate measures if necessary. To this end, the mass of NOx absorbed by the NOx storage catalytic converter is determined within a diagnostic period using a measurement signal of the NOx sensor. At the same time, an absorbed NOx target mass is calculated using a model for the NOx storage catalytic converter. A ratio of the NOx mass to the NOx target mass is then compared to predetermined limit values to determine the functioning of the NOx sensor. The aim of the invention is alternatively accomplished by measuring a duration time for a complete NOx regeneration of the NOx storage catalytic converter.

Abstract: An O2-sensor fault diagnosis apparatus and method therefor, which are capable of detecting wire breaking of an O2-sensor with reliability and successively performing fault diagnosis with minimal effect on an exhaust gas. An O2-sensor 19 detects concentration of oxygen contained in an exhaust gas of an engine 1. An ECU 20 controls a quantity of fuel supplied to the engine 1 through feedback control according to an output signal of the O2-sensor. A fault diagnosis portion changes an input resistance value of an input circuit that is connected to the O2-sensor 19 and constitutes the ECU 20 each time a control condition for determining that the O2-sensor 19 is in an inactive state is satisfied, determines that wire breaking occurs in the O2-sensor 19 only if the output voltage of the O2-sensor 19 exceeds a predetermined voltage, and activates an informing portion to send a notice showing that there is a fault in the O2-sensor 19.

Abstract: A diagnostic equipment for an exhaust gas cleaning apparatus installed for an engine, comprising a misfire detector which detects the misfire of the engine, and a secondary-air-system failure detector which detects the failure of a secondary air system. An index corrector corrects a deterioration index calculated by a deterioration-index calculator, in accordance with the detected result of the detector. A deterioration decision unit decides if the diagnostic equipment has failed, by the use of the corrected deterioration index. In a case where the extent of the misfire or the like is severe, a decision interrupter interrupts the decision of the deterioration decision unit. Thus, even when the misfire of the engine or the failure of the secondary air system has occurred, the detection of the deterioration of a catalyst does not err. It is therefore avoided to erroneously replace the catalyst which has not deteriorated yet, or to run the engine in spite of the deterioration of the catalyst.

Abstract: A deterioration determining apparatus and a deterioration determining method are applied to an engine in which a feedback control of an air-fuel ratio is performed by calculating an air-fuel ratio correction coefficient based on an output of an oxygen sensor, and response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor is set so as to be variable. In the deterioration determining apparatus and the deterioration determining method, a deterioration determining value concerning a determination as to whether the oxygen sensor has deteriorated is set so as to be variable according to the set response of the air-fuel ratio correction coefficient with respect to the output of the oxygen sensor, and the determination as to whether the oxygen sensor has deteriorated is made based on an inversion cycle of the output of the oxygen sensor and the deterioration determining value.

Abstract: There is provided a degradation determining system for an exhaust gas sensor, which, even when unexpected changes occur in the air-fuel ratio during execution of air-fuel ratio control, can determine degradation of the sensor by suppressing adverse influence of noise caused by the changes on the output from the sensor, to thereby enhance the accuracy of the degradation determination. In the degradation determining system, a determining input signal IDSIN for determining the degradation of the sensor is generated, and a modulation output (u(k), DSMSGNS(k), us(k), or ud(k)) is generated by modulating the determining input signal IDSIN by using any one of the &Dgr;&Sgr; modulation algorithm, the &Sgr;&Dgr; modulation algorithm, and the &Dgr; modulation algorithm. Degradation of the sensor is determined based on the output KACT delivered from the sensor when the fuel injection amount is controlled based on the generated modulation output.

Abstract: In a method and a circuit for installation-exchange protection of at least two measuring sensors for detecting physical/chemical variables of an exhaust gas in a system for exhaust-gas aftertreatment in an internal combustion engine, especially of a motor vehicle, voltage signals of the at least two measuring sensors are read in such that the read-in voltage signals are digitized and the digitized voltage values are buffer-stored. The buffer-stored voltage values each are buffer-stored as a copy. The voltage values buffer-stored as a copy are evaluated on the basis of characteristic voltage variables. During the process it is checked whether an exchange of the at least two measuring sensors has occurred and that, as a function of the test result, the buffer-stored voltage values are each buffer-stored as copies in a crosswise manner.

Abstract: A control valve module for gaseous fuels on spark ignited reciprocating engines is presented. The control valve module has a valve that controls gaseous fuel flow to a mixer or other device for air/fuel ratio control, an actuator for moving the valve position, and a controller. The controller receives a signal from a heated exhaust gas oxygen (HEGO) sensor that is an indication of the fuel/air ratio and actuates the valve to control the combustion mixture to a precise stoichiometric ratio.

Abstract: There is provided a degradation determining system for an exhaust gas sensor, which, even when unexpected changes occur in the air-fuel ratio during execution of air-fuel ratio control, can determine degradation of the sensor by suppressing adverse influence of noise caused by the changes on the output from the sensor, to thereby enhance the accuracy of the degradation determination. In the degradation determining system, a determining input signal IDSIN for determining the degradation of the sensor is generated, and a modulation output (u(k), DSMSGNS(k), us(k), or ud(k)) is generated by modulating the determining input signal IDSIN by using any one of the &Dgr;&Sgr; modulation algorithm, the &Sgr;&Dgr; modulation algorithm, and the &Dgr; modulation algorithm. Degradation of the sensor is determined based on the output KACT delivered from the sensor when the fuel injection amount is controlled based on the generated modulation output.

Abstract: A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, such as after an engine cold start, the method operates an engine with a first group of cylinders having a first ignition timing, and a second group of cylinders having a second ignition timing more retarded than the first group. In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also can change to combusting all cylinders at substantially the same ignition timing under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

Abstract: A control valve module for gaseous fuels on spark ignited reciprocating engines is presented. The control valve module has a valve that controls gaseous fuel flow to a mixer or other device for air/fuel ratio control, an actuator for moving the valve position, and a controller. The controller receives a signal from a heated exhaust gas oxygen (HEGO) sensor that is an indication of the fuel/air ratio and actuates the valve to control the combustion mixture to a precise stoichiometric ratio.

Abstract: An O2 amount in the intake air is determined based on a fresh air and an EGR gas. A consumed O2 amount is determined with a command injection amount Qr. Then, the consumed O2 amount is subtracted from the O2 amount in the intake air to obtain an exhaust O2 amount. An exhaust O2 concentration is estimated based on the exhaust O2 amount. According to the invention, the system is not affected by a delay for the exhaust gas to reach an O2 sensor and a delay of the chemical reaction in the O2 sensor. Therefore, the exhaust O2 concentration can be highly precisely estimated compare to the case in which the exhaust O2 concentration is detected by the O2 sensor.

Abstract: The abnormality diagnosis apparatus includes an oxygen sensor for detecting a concentration of oxygen in exhaust gases of an internal combustion engine, an injector for injecting fuel into the internal combustion engine, a feedback control element for driving the injector according to the concentration of oxygen to control an amount of fuel supplied to the internal combustion engine in a feedback manner, a forced fuel correction element for correcting an amount of fuel controlled by the feedback control element in a forced manner, and an abnormality determination element for determining the presence or absence of abnormality in the injector. The abnormality determination element determines the presence or absence of abnormality in the injector based on the concentration of oxygen detected by the oxygen sensor in the course of a forced fuel correction control operation carried out by the forced fuel correction element.

Abstract: In detecting a deterioration of an air-fuel ratio sensor, a sensor output change speed integrated value is calculated when an element temperature of a solid electrolyte is stabilized at a low temperature. Successively, a sensor output change speed integrated value is calculated when the solid electrolyte element is stabilized at a high temperature. Finally, a deviation between the change speed integrated values is calculated. By comparing the deviation amount with a predetermined determinant, presence or absence of the deterioration is determined.

Abstract: In a control device, in a control device of an internal combustion engine provided with an internal combustion engine main body mounted to a vehicle and a heater operating on the basis of an output from a specific sensor given as a trigger at least before the internal combustion engine main body starts, whether or not the heater is operated before the start is stored, and it is judged that the sensor has failed when operation of the heater is not stored.

Abstract: A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, such as after an engine cold start, the method operates an engine with a first group of cylinders having a first ignition timing, and a second group of cylinders having a second ignition timing more retarded than the first group. In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also can change to combusting all cylinders at substantially the same ignition timing under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.

Abstract: An engine control system has a self-diagnosis function of an exhaust system. The self-diagnosis function includes a first mode for detecting a failure or abnormality of the exhaust system as a whole, and a second mode for determining and locating a specific failed component in the exhaust system. The first mode is executed during the engine is operated under a normal condition. Therefore it is possible to detect the failure of the exhaust system without lowering a drive performance or increasing emissions. In case of detecting any failure in the first mode, the second mode is activated in response to a command signal that can be entered via a service tool. In the second mode, the engine is operated in order to determine the failed component. In the second mode, determining the failed component takes priority over keeping the drive performance or reducing emissions.

Abstract: An air/fuel ratio sensor (4) and a three-way catalytic converter (3A) having an oxygen storage function are provided in an exhaust passage (2) of an internal combustion engine (1). A controller (6) runs the engine (1) under the alternating application of a stoichiometric air/fuel ratio and a rich air/fuel ratio, and a diagnosis of deterioration in the air/fuel ratio sensor (4) is performed on the basis of the amplitude of variation in the air/fuel ratio detected by the air/fuel ratio sensor (4). By executing the diagnosis only immediately after a fuel cut, the amount of oxygen stored in the three-way catalytic converter (3A) at the start point of the diagnosis is equal to the maximum amount. When the rich air/fuel ratio is applied, the converter (3A) releases the stored oxygen to maintain the exhaust gas purification performance of the converter (13).

Abstract: An O2 amount in the intake air is determined based on a fresh air and an EGR gas. A consumed O2 amount is determined with a command injection amount Qr. Then, the consumed O2 amount is subtracted from the O2 amount in the intake air to obtain an exhaust O2 amount. An exhaust O2 concentration is estimated based on the exhaust O2 amount. According to the invention, the system is not affected by a delay for the exhaust gas to reach an O2 sensor and a delay of the chemical reaction in the O2 sensor. Therefore, the exhaust O2 concentration can be highly precisely estimated compare to the case in which the exhaust O2 concentration is detected by the O2 sensor.

Abstract: A failure determination device that detects the humidity of exhaust gases from an internal combustion engine and a control system for an exhaust passage changeover valve, which can switch the changeover valve with appropriate timing, thereby enabling sufficient purification of exhaust gases. An operating condition of the engine is detected. Based on the detected operating condition of the engine, it is determined whether the engine is in an operating condition in which failure determination of the humidity sensor can be executed. It is determined whether the humidity sensor has failed, based on a result of detection by the humidity sensor, when it has been judged that the failure determination of the humidity sensor can be executed.

Abstract: In a constitution for feedback controlling an air-fuel ratio using an oxygen concentration detector in which a detection signal thereof has a linearity to the air-fuel ratio within a predetermined air-fuel ratio range inclusive of a stoichiometric air-fuel ratio, when the detection signal from the oxygen concentration detector is outside a region indicating the linearity, a change in air-fuel ratio feedback control signal is limited to be smaller than that when the detection signal from the oxygen concentration detector is within the region indicating the linearity.

Abstract: An abnormality diagnosis apparatus of an internal combustion engine is provided which is capable of improving reliability in abnormality determination as well as making abnormality determination at high frequencies. The abnormality diagnosis apparatus includes an oxygen sensor for detecting a concentration of oxygen in exhaust gases of an internal combustion engine, an injector for injecting fuel into the internal combustion engine, a feedback control element for driving the injector according to the concentration of oxygen to control an amount of fuel supplied to the internal combustion engine in a feedback manner, a forced fuel correction element for correcting an amount of fuel controlled by the feedback control element in a forced manner, and an abnormality determination element for determining the presence or absence of abnormality in the injector.

Abstract: Based upon a purge air quantity supplied via a purge control valve to an intake system of an engine, an intake air amount into the engine, a fuel injection quantity into the engine, and an air-fuel ratio of the combustion mixture, a fuel vapor concentration is calculated as fuel vapor concentration=(intake air amount+purge air quantity air-fuel ratio×fuel injection quantity)/(the air-fuel ratio+1).

Abstract: A catalytic converter (3) having a three-way catalyst which stores oxygen is disposed in the exhaust passage (2) of an engine (1). An oxygen storage amount of the catalyst is estimated based on the output of a universal exhaust gas oxygen sensor (4) provided upstream of the catalytic converter (3). A control unit (6) controls an air-fuel ratio of the fuel mixture supplied to the engine (1) through a fuel injector (12) so that the oxygen storage amount coincides with a target value. An excess/deficiency oxygen amount in the exhaust gas is accumulated when the output of an oxygen sensor (5) which detects the oxygen concentration downstream of the catalytic converter (3) is in an excess oxygen region which is higher than a stoichiometric oxygen concentration region. An average oxygen excess ratio is calculated by dividing the accumulated value by an accumulated intake air amount. The output of the universal exhaust gas oxygen sensor (4) is corrected based on the average oxygen excess ratio.

Abstract: The present invention increases the frequency of the LAF sensor deterioration determination in the case that air-fuel ratio control is being carried out while the deterioration of the LAF sensor is being monitored. When the monitor conditions are no longer satisfied during the deterioration determination of the LAF sensor (as shown in (a) and (b) of FIG. 6), the LAF prohibition timer is operated (as shown in (c) of FIG. 6), and switching to a lean burn is prohibited for a predetermined time interval (for example, 7 seconds), and in addition, after the LAF sensor deterioration determination has completed, after passage of a time interval shorter than this predetermined time interval (for example, 2 seconds) (as shown in figures (c) and (d) of FIG. 6), a lean burn is permitted.

Abstract: A diagnostic equipment for an exhaust gas cleaning apparatus installed for an engine, comprising a misfire detector which detects the misfire of the engine, and a secondary-air-system failure detector which detects the failure of a secondary air system. An index corrector corrects a deterioration index calculated by a deterioration-index calculator, in accordance with the detected result of the detector. A deterioration decision unit decides if the diagnostic equipment has failed, by the use of the corrected deterioration index. In a case where the extent of the misfire or the like is severe, a decision interrupter interrupts the decision of the deterioration decision unit. Thus, even when the misfire of the engine or the failure of the secondary air system has occurred, the detection of the deterioration of a catalyst does not err. It is therefore avoided to erroneously replace the catalyst which has not deteriorated yet, or to run the engine in spite of the deterioration of the catalyst.

Abstract: A method and apparatus for gas-dynamic cold spraying a liner 3 in a cylinder 2 of an aluminum engine block 1 is provided. The gas-dynamic cold spray liner 3 allows the aluminum engine block 1 to have a hardened cylinder surface 10 without the induction of residual hoop stress within the aluminum engine block 1.

Abstract: A rotary vane combustion engine is provided that has a plurality of vane cells. This rotary vane combustion engine includes a rotor having a plurality of vanes; a stator enclosing the rotor to form a plurality of vane cells between the plurality of vanes; one or more intake ports for providing intake charge to the vane cells; one or more exhaust ports for removing exhaust gas from one of the vane cells; and a variable bandwidth fuel-air source connected to at least one of the intake ports for providing a discrete band of mixed fuel and air having a desired axial width to each of the plurality of vane cells. By providing a discrete band of fuel and air to each of the vane cells, this rotary vane combustion engine will allow the machine or engine to run at lower power without requiring it to run a vacuum to lower the density of mixed fuel and air. As a result, vacuum pumping losses can be substantially eliminated and the machine or engine can operate more efficiently.

Abstract: An apparatus for accurately and promptly determining a failure of an oxygen concentration sensor. The oxygen concentration sensor is arranged at a location downstream of a catalyst in an exhaust system of an internal combustion engine. The apparatus measures a time period elapsed after termination of a fuel cut-off operation, and calculates an integrated amount SUMSVS of exhaust gases exhausted after the termination of the fuel cut-off operation. A failure of the oxygen concentration sensor is determined depending on whether or not a signal value SVO2 of a signal from the oxygen concentration sensor has crossed a predetermined threshold value #SVO2CHK. Further, when a predetermined time period #TMFCCKD has elapsed, if the signal value SVO2 has not crossed the predetermined threshold value #SVO2CHK, and at the same time when the integrated amount SUMSVS of the exhaust gases has not reached a predetermined value #SUMSVAFC the failure determination is suspended.

Abstract: In a control device, in a control device of an internal combustion engine provided with an internal combustion engine main body mounted to a vehicle and a heater operating on the basis of an output from a specific sensor given as a trigger at least before the internal combustion engine main body starts, whether or not the heater is operated before the start is stored, and it is judged that the sensor has failed when operation of the heater is not stored.

Abstract: A diagnosis system for a wide-range A/F sensor receives an air-fuel ratio (A/F) of air-fuel mixture supplied to an engine for the A/F sensor. An control unit of the diagnosis system corrects an A/F controlled object of a feedback control on the basis of a detection result of the A/F sensor to adjust the A/F at a target A/F. The control unit diagnoses an abnormality of the A/F sensor from variation of the detection value of the A/F sensor during a time period from the start of the switching of the target A/F. The control unit sets a control gain of an A/F feedback control at a value greater than a normal control gain during the diagnosis.

Abstract: An engine combustion controller for an engine having a fuel supply system selects an engine combustion mode from one of lean combustion, in which an air fuel mixture leaner than a stoichiometric mixture is burned, and stoichiometric combustion, in which a stoichiometric mixture is burned, in accordance with an operating state of the engine and controls, via feedback, the air fuel ratio of the air fuel mixture when the stoichiometric combustion is performed using air-fuel ratio compensating value that are based on the composition of the engine exhaust gas. A preliminary tester checks the fuel supply system and determines that the fuel supply system is in a normal state when certain preliminary test conditions are satisfied, which includes checking the feedback compensating value. A prohibiter prevents lean combustion when the preliminary tester determines that the state of the fuel supply system is ambiguous.

Abstract: Under normal conditions, the temperature of an oxygen ion-conductive element provided in a sensor body is about 700° C., and the element impedance is about 30 &OHgr;. If there is a fault in the sensor body or a sensor body drive circuit, the current becomes zero and the element impedance becomes infinite. If a heater has deteriorated, the element temperature rises only up to, for example, about 550° C., and the element impedance becomes about 150 &OHgr;. If there is a fault in the heater or the heater drive circuit, the element is heated only by exhaust gas, so that the element temperature rises only up to about the temperature of exhaust gas and the element impedance becomes a value corresponding to an element temperature of about 300° C. Three reference values Z1, Z2, Z3 are set for comparison with the detected value of element impedance in order to perform fault diagnosis.