Abstract: When detection of malfunction is interrupted for any reason, the integrated purge amount is cleared, and the next malfunction judgment conditions are determined satisfied when said integrated purge amount is not less than a second predetermined value shorter than said first predetermined value. The detection of malfunction is carried out again by purging the canister taking a time shorter than conventionally required. As a result, a fuel gas purge system having failure diagnostic function and being capable of improving frequency in detection of malfunction and preventing deterioration in drivability and emission is obtained.

Abstract: When detection of malfunction is interrupted for any reason, the integrated purge amount is cleared, and the next malfunction judgment conditions are determined satisfied when said integrated purge amount is not less than a second predetermined value shorter than said first predetermined value. The detection of malfunction is carried out again by purging the canister taking a time shorter than conventionally required. As a result, a fuel gas purge system having failure diagnostic function and being capable of improving frequency in detection of malfunction and preventing deterioration in drivability and emission is obtained.

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: An abnormality detection apparatus of an engine temperature adjusting thermostat is provided which is capable of accurately grasping the state of an amount of heat generated by an engine to prevent misdetection of abnormality in the thermostat for improved reliabilty.

Abstract: An abnormality detecting apparatus for a fuel evaporative emission control system which ensures enhanced reliability includes a canister (9) disposed in a purge passage, a purge control valve (10), a control means (20) for controlling opening/closing of the purge control valve (10) in dependence on engine operation states, a means (18) for detecting an intake pressure (Pb), a means for detecting at least one of an atmospheric pressure (PA), an outside air temperature (TG), an intake air temperature (TA) and a fuel temperature (TT), a means (19) for detecting a fuel tank pressure (Pt), a means (20) for determining validity of abnormality decision enabling conditions in the case where concentration of fuel gas is lower than a reference value for comparison, a means (20) for regulating a purge rate in dependence on an intake pressure (Pb) when the abnormality decision enabling conditions are valid, a means (20) for detecting occurrence of abnormality in the fuel evaporative emission control system on the basis o

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: An abnormality detection apparatus of an engine temperature adjusting thermostat is provided which is capable of accurately grasping the state of an amount of heat generated by an engine to prevent misdetection of abnormality in the thermostat for improved reliabilty.

Abstract: An abnormality detecting apparatus for a fuel evaporative emission control system which ensures enhanced reliability includes a canister (9) disposed in a purge passage, a purge control valve (10), a control means (20) for controlling opening/closing of the purge control valve (10) in dependence on engine operation states, a means (18) for detecting an intake pressure (Pb), a means for detecting at least one of an atmospheric pressure (PA), an outside air temperature (TG), an intake air temperature (TA) and a fuel temperature (TT), a means (19) for detecting a fuel tank pressure (Pt), a means (20) for determining validity of abnormality decision enabling conditions in the case where concentration of fuel gas is lower than a reference value for comparison, a means (20) for regulating a purge rate in dependence on an intake pressure (Pb) when the abnormality decision enabling conditions are valid, a means (20) for detecting occurrence of abnormality in the fuel evaporative emission control system on the basis o

Abstract: A dual-sensor type air-fuel ratio control system for an internal combustion engine. A catalytic converter 10 is disposed in an exhaust pipe 9, together with a first upstream air-fuel ratio sensor 11 and a second, downstream air-fuel ratio sensor 12. An electronic unit 30A controls the air-fuel ratio of a mixture supplied to the engine, and includes first and second arithmetic circuits 51, 52 for determining first and second air-fuel ratio control quantities Cf1, C2' on the basis of the first and second air-fuel ratio signals V1, V2, and a circuit 53, 54 for correcting the first control quantity with the second one to determine a target air-fuel ratio control quantity J for the fuel injection. A filter 50 is provided for the first air-fuel ratio signal to compensate for variations in the output characteristic of the first sensor.

Abstract: A deterioration detecting apparatus for catalytic converter is provided to surely detect deterioration of a catalytic converter. In the deterioration detecting apparatus for catalytic converter, an electronic control unit decides whether or not a catalyst is activated in the catalytic converter for removing injurious ingredients from an exhaust gas of an engine, and the electronic control unit decides the deterioration of the catalyst only when it decides that the catalyst is activated. It is thereby possible to avoid erroneous decision of the deterioration since the deterioration of the catalyst is not decided when the catalytic converter is not activated.

Abstract: A dual-sensor type air-fuel ratio control system for an internal combustion engine. A catalytic converter is disposed within an exhaust pipe for purifying an exhaust gas. A first air-fuel ratio sensor 11 is disposed upstream of the catalyst for detecting concentration of a particular component of the exhaust gas to output a first air-fuel ratio signal V1 indicating the concentration. A second air-fuel ratio sensor 12 is disposed downstream of the catalyst for detecting concentration of the particular exhaust gas component to output a second air-fuel ratio signal V2 indicating the concentration. An electronic control unit M8 controls a target air-fuel ratio of a mixture supplied to the engine by arithmetically determining an air-fuel ratio control quantity on the basis of the first and second air-fuel ratio signals.

Abstract: A dual-sensor type air-fuel ratio control system for an internal combustion engine. A catalytic converter is disposed within an exhaust pipe for purifying an exhaust gas. A first air-fuel ratio sensor 11 is disposed upstream of the catalyst for detecting concentration of a particular component of the exhaust gas to output a first air-fuel ratio signal V1 indicating the concentration. A second air-fuel ratio sensor 12 is disposed downstream of the catalyst for detecting concentration of the particular exhaust gas component to output a second air-fuel ratio signal V2 indicating the concentration.

Abstract: A dual-sensor type air-fuel ratio control system for an internal combustion engine. A catalytic converter disposed within an exhaust pipe is flanked by first and second upstream and downstream air-fuel ratio sensors 11, 12. An apparatus for detecting deterioration of the catalytic converter includes a deterioration parameter calculating circuit 60, a filter circuit 61, and a comparison decision circuit 62. The decision circuit compares a filtered deterioration parameter value .gamma.f with a predetermined value corresponding to a detected operation state of the engine to determine deterioration of the catalyst when the deterioration parameter value exceeds the predetermined value.

Abstract: A dual-sensor type air-fuel ratio control system for an internal combustion engine. A catalytic converter disposed within an exhaust pipe is flanked by first and second upstream and downstream air-fuel ratio sensors 11, 12. An apparatus for detecting deterioration of the catalytic converter includes a deterioration decision circuit 54 for determining deterioration of the catalyst on the basis of at least the second air-fuel ratio sensor signal, a filter circuit 50 for filtering the second sensor signal, and a comparison circuit 51 for comparing the second sensor filtered and unfiltered signals. The deterioration decision circuit compares a deterioration parameter value derived from the result of the comparison with a predetermined value corresponding to a detected operation state of the engine to determine deterioration of the catalyst when the deterioration parameter value exceeds the predetermined value.

Abstract: In a trouble diagnosis device for an exhaust gas return control system in which a returning amount of exhaust gas is changed at a predetermined value to obtain a variation between operating conditions of the engine under before thus changing and under after thus changing, and the variation is compared with a predetermined value, thereby to determine whether or not the exhaust gas return control system is out of order. A variation rate in the detection value of the operating conditions of the engine is obtained every predetermined period of time, and when the variation rate thus obtained exceeds a predetermined rate, the trouble diagnosis operation for the exhaust gas return control system is suspended.

Abstract: A malfunction sensing apparatus for a fuel vapor control system includes a fuel tank and a canister containing an adsorbent for adsorbing fuel vapor. The canister has an inlet connected to the fuel tank and an outlet. A purge control valve is connected to the outlet for connecting and disconnecting the outlet of the canister from the air intake pipe of an engine. A pressure sensor senses the internal pressure of the fuel tank. A malfunction sensing means responsive to the pressure sensor senses a malfunction when the purge control valve is open and the pressure sensed by the pressure sensor is above a prescribed value. A prohibiting means senses the rate of change and/or the magnitude of the pressure sensed by the pressure sensor with the purge control valve closed and prohibits malfunction sensing by the malfunction sensing means when the rate of change of the pressure exceeds a prescribed rate and/or the magnitude of the pressure exceeds a prescribed value.

Abstract: A failure diagnosis device of an EGR control device provided with an exhaust gas recirculating passage for recirculating exhaust gas of an engine to an intake side of the engine and a recirculating valve for controlling to open and close the exhaust gas recirculating passage, which controls to open and close the recirculating valve comprising: a running condition detecting means for detecting a running condition of the engine; a failure diagnosis means for performing a failure diagnosis of the EGR control device by determining whether a difference between the first running condition when the recirculating valve is open and the second running condition when the recirculating valve is closed, is a predetermined value or more; and an ignition timing controlling means for performing an ignition timing controlling in accordance with a change of the running condition when the recirculating valve is switched from an open state to a closed state and from the closed state to the open state.