Abstract: In the exhaust gas control system, the electronic control unit is configured to execute first air-fuel ratio control for controlling an air-fuel ratio of an air-fuel mixture in a part of cylinders to a lean air-fuel ratio and controlling an air-fuel ratio of an air-fuel mixture in the other part of the cylinders to a rich air-fuel ratio is executed. The electronic control unit is configured to execute second air-fuel ratio control to perform malfunction diagnosis. The electronic control unit is configured to execute second air-fuel ratio control when the execution of the first air-fuel ratio control is interrupted after the temperature of the three-way catalyst becomes equal to or higher than the diagnosis temperature.

Abstract: A controller is configured to execute a dither control process of operating fuel injection valves such that at least one of cylinders is a lean combustion cylinder, in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and at least another one of the cylinders is a rich combustion cylinder, in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and a limiting process of limiting the dither control process such that the difference in the air-fuel ratio between the cylinders is smaller in a change period, in which a gear ratio of the multi-speed transmission is changed, than in periods except for the change period.

Abstract: In a dither control process of a fuel injection valve, one of a number of cylinders is set as a rich combustion cylinder and another one of the cylinders is set as a lean combustion cylinder. The temperature raising capability required for the dither control process in the second mode is higher than the temperature raising capability in the first mode. A time integration value is obtained by integrating an absolute value of a difference between an air-fuel ratio of the rich combustion cylinder and an air-fuel ratio of the lean combustion cylinder over a predetermined period. In an enlarging process, a time integration value of the second mode is set to be greater than a time integration value of the first mode.

Abstract: A controller for an internal combustion engine is configured to execute a dither control process and an enlarging process. The enlarging process includes at least one of the following two processes: a process of causing an operation region of the internal combustion engine in which the dither control process is executed to be larger in a case in which an amount of particulate matter trapped by the filter is large than in a case in which the amount is small; and a process of causing a degree of richness of the rich combustion cylinder and a degree of leanness of the lean combustion cylinder to be greater in a case in which the amount of particulate matter trapped by the filter is large than in a case in which the amount of particulate matter trapped by the filter is small.

Abstract: A controller for an internal combustion engine includes processing circuitry that performs a dither control process on condition that a temperature increase request of a catalyst is made. The processing circuitry operates fuel injection valves so that during the dither control process, one or more cylinders are lean combustion cylinders in a first period and another one or more cylinders are rich combustion cylinders and so that the average value of an exhaust gas-fuel ratio is a target air-fuel ratio in a second period including the first period. The dither control process is restricted in a manner that, on condition that the rich process is performed, the degree of richening of the richest exhaust gas-fuel ratio of exhaust gas-fuel ratios in the cylinders is reduced.

Abstract: A controller includes an air-fuel ratio control unit that calculates an air-fuel ratio F/B correction value and an air-fuel ratio learning value and corrects an amount of fuel supplied to each cylinder based on the air-fuel ratio F/B correction value FAF and the air-fuel ratio learning value KG. The controller further includes a dither control unit that executes dither control to adjust the amount of fuel supplied to each cylinder, corrected by the air-fuel ratio control unit, so that at least one of the cylinders is set to a rich combustion cylinder and at least a further one of the cylinders is set to a lean combustion cylinder. When the dither control is executed, the air-fuel ratio control unit prohibits execution of air-fuel ratio learning control and executes air-fuel ratio feedback control.

Abstract: A controller for an internal combustion engine includes a processing circuit that performs a dither control process on condition that a temperature increase request of a catalyst is made. The processing circuit operates fuel injection valves so that during the dither control process, one or more cylinders are lean combustion cylinders in a first period and another one or more cylinders are rich combustion cylinders and so that the average value of an exhaust gas-fuel ratio is a target air-fuel ratio in a second period including the first period. The dither control process is restricted in a manner that, on condition that the rich process is performed, the degree of richening of the richest exhaust gas-fuel ratio of exhaust gas-fuel ratios in the cylinders is reduced.

Abstract: When a request for temperature increase of a three-way catalyst is made, a CPU executes dither control in which one of a plurality of cylinders is set as a rich combustion cylinder with a richer air-fuel ratio than a stoichiometric air-fuel ratio and the remaining cylinders are set as lean combustion cylinders with a leaner air-fuel ratio than the stoichiometric air-fuel ratio. When not executing the dither control, the CPU learns a rich learning value that is a learning value of a degree of a rich imbalance based on an upstream-side air-fuel ratio. When the rich learning value is greater than or equal to a predetermined value, the CPU prohibits the dither control.

Abstract: A controller for an internal combustion engine is configured to execute a dither control process, a purge control process, and a limiting process. The dither control process operates the fuel injection valves such that at least one of the cylinders is a lean combustion cylinder, in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, and at least another one of the cylinders is a rich combustion cylinder, in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio. The purge control process controls the purge flow rate by operating the adjustment device. The limiting process limits the purge control process such that, when the dither control process is being executed, the purge flow rate is reduced as compared to a case in which the dither control process is not being executed.

Abstract: A control device for an internal combustion engine includes an electronic control unit configured to perform dither control processing for controlling the fuel injection valve based on a requested injection amount such that a part of cylinders among a plurality of cylinders becomes a lean combustion cylinder and cylinders different from the part of cylinders among the cylinders become a rich combustion cylinder, and restriction processing for, in a case where the requested injection amount is equal to or greater than a first injection amount, making no restriction on the dither control processing, and in a case where the requested injection amount is within a second injection amount range of an injection amount smaller than the first injection amount, restricting the dither control processing to a side where a leaning degree of an air-fuel ratio of a cylinder having a leanest air-fuel ratio among the cylinders decreases.

Abstract: A control device for an internal combustion engine includes an electronic control unit configured to determine whether or not cylinder-specific air-fuel ratio processing is being executed in which an air-fuel ratio of at least one of a plurality of cylinders is controlled to be a rich air-fuel ratio and an air-fuel ratio of at least one of the other cylinders is controlled to be a lean air-fuel ratio. The electronic control unit updates a first learning value in which a result of comparison between a knock strength of the internal combustion engine and a first determination value is reflected when the cylinder-specific air-fuel ratio processing is not being executed. The electronic control unit prohibits updating of the first learning value and calculates a target ignition timing of the internal combustion engine based on the first learning value when the cylinder-specific air-fuel ratio processing is being executed.

Abstract: A controller for an internal combustion engine is configured to execute a dither control process and an exhaust gas recirculation (EGR) control process. The dither control process includes, when a request to increase a temperature of a catalyst is made, operating the fuel injection valves corresponding to respective cylinders to control the air-fuel ratio in some of the cylinders to become lean and control the air-fuel ratio in other cylinders to become rich. The EGR control process includes operating an adjustment actuator to control an EGR rate. The EGR control process includes operating the adjustment actuator such that the EGR rate is lower when the dither control process is being executed than when the dither control process is not being executed.

Abstract: An abnormality diagnosis device for an engine includes an electronic control unit configured to execute temperature rise processing by controlling an air-fuel ratio of at least one of a plurality of cylinders to be a rich air-fuel ratio and controlling an air-fuel ratio of each of the other cylinders to be a lean air-fuel ratio. The electronic control unit is configured to determine whether or not the execution of the temperature rise processing is ongoing, to execute abnormality determination processing to determine whether or not the engine is in an abnormal state, to execute the abnormality determination processing based on whether or not the variation degree during stop of the temperature rise processing exceeds a first determination value, and to execute the abnormality determination processing based on whether or not the variation degree during the execution of the temperature rise processing exceeds a second determination value.

Abstract: A misfire determination device for an internal combustion engine includes an electronic control unit configured to determine whether execution of temperature rise processing in which a temperature of a catalyst is raised by an air-fuel ratio of one of the cylinders being controlled to be a rich air-fuel ratio lower than a stoichiometric air-fuel ratio and an air-fuel ratio of each of the other cylinders being controlled to be a lean air-fuel ratio higher than the stoichiometric air-fuel ratio is ongoing, determine occurrence of misfire based on whether a rotation variation amount of the internal combustion engine during non-execution of the temperature rise processing exceeds a first misfire determination value, and determine occurrence of misfire based on whether the rotation variation amount during the execution of the temperature rise processing exceeds a second misfire determination value exceeding the first misfire determination value.

Abstract: A control for an internal combustion engine makes an air-fuel ratio in at least one of a plurality of cylinders equal to a rich air-fuel ratio smaller than a theoretical air-fuel ratio, makes an air-fuel ratio in each of the other remaining ones of the plurality of the cylinders equal to a lean air-fuel ratio larger than the theoretical air-fuel ratio, executes a temperature raising process for raising a temperature of a catalyst that purifies exhaust gas from the plurality of the cylinders, executes a detection process for detecting a degree of dispersion of the air-fuel ratio among the plurality of the cylinders, and executes a determination process for determining, based on the detected degree of dispersion, whether or not a plurality of fuel injection valves corresponding to the plurality of the cylinders respectively are normal, and executes the detection process while avoiding a period of the temperature raising process.

Abstract: In a control apparatus for an internal combustion engine, The ignition timing in a rich-cylinder is corrected toward a retardation side from a theoretical-MBT such that the torque generated in the rich-cylinder exceeds a torque generated in the rich-cylinder at the theoretical-MBT, and the ignition timing in a lean-cylinder is corrected toward an advancement side from the theoretical-MBT such that the torque generated in the lean-cylinder exceeds a torque generated in the lean-cylinder at the theoretical-MBT, when a temperature raising process is being executed, and the ignition timing in the rich-cylinder is corrected further toward the retardation side such that the torque generated in the rich-cylinder becomes equal to or smaller than a maximum theoretical generated torque and equal to or larger than the torque generated in the lean-cylinder at the theoretical-MBT, when the temperature raising process is being executed and the engine is in a low-load operating state.

Abstract: A control apparatus for an internal combustion engine includes an ECU configured to: determine whether a temperature-increasing process is being executed; calculate a target value of a parameter correlated with a difference between a rich air-fuel ratio and a lean air-fuel ratio achieved in the temperature-increasing process, based on an operating state of the internal combustion engine; calculate, as an upper limit, a value of the parameter required to increase the temperature of the catalyst to a predetermined upper limit temperature; determine whether the target value is equal to or lower than the upper limit; adjust the parameter used in the temperature-increasing process to the target value when the target value is determined to be equal to or lower than the upper limit; and adjust the parameter used in the temperature-increasing process to the upper limit when the target value is determined to be higher than the upper limit.

Abstract: In the exhaust gas control system, the electronic control unit is configured to execute first air-fuel ratio control for controlling an air-fuel ratio of an air-fuel mixture in a part of cylinders to a lean air-fuel ratio and controlling an air-fuel ratio of an air-fuel mixture in the other part of the cylinders to a rich air-fuel ratio is executed. The electronic control unit is configured to execute second air-fuel ratio control to perform malfunction diagnosis. The electronic control unit is configured to execute second air-fuel ratio control when the execution of the first air-fuel ratio control is interrupted after the temperature of the three-way catalyst becomes equal to or higher than the diagnosis temperature.

Abstract: An exhaust gas control device for an internal combustion engine includes an estimation unit configured to estimate a temperature of a catalyst on the basis of an acquired operation state of the internal combustion engine and a difference between a lean air-fuel ratio and a rich air-fuel ratio which are set as target air-fuel ratios during execution of catalyst regeneration control, a determination unit configured to determine whether the estimated temperature of the catalyst is higher than a threshold value during execution of the catalyst regeneration control, and a prohibition unit configured to prohibit the catalyst regeneration control when it is determined that the estimated temperature of the catalyst is higher than the threshold value during execution of the catalyst regeneration control.