Abstract: A controller for an internal combustion engine is configured to execute a determination process that determines that a deviation between a first change amount and a second change amount during a fuel cutoff operation is less than or equal to a threshold, and an anomaly diagnosing process that determines that an exhaust purification device is in a detached state when the determination process determines that the deviation is less than or equal to the threshold. The first change amount and the second change amount are change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively. The controller is configured to interrupt the determination process when the upstream-side temperature increases within a determination period.

Abstract: An upstream integrated value is an integrated value of a difference obtained by subtracting an upstream gas temperature at a starting point in time of integration from the upstream gas temperature after starting of the internal combustion engine. A downstream integrated value is an integrated value of a difference obtained by subtracting a downstream gas temperature at the starting point in time of the integration from the downstream gas temperature after the starting of the internal combustion engine. An anomaly diagnosing process obtains an anomaly determination result indicating that the exhaust purification device is in a removed state when a deviation between the upstream integrated value and the downstream integrated value is smaller than a reference level. The determination threshold is higher than a dew point.

Abstract: A controller for an internal combustion engine is configured to execute a determination process and an anomaly diagnosing process. The determination process is a process of determining that a deviation between a first change amount and a second change amount during a fuel cutoff operation is less than or equal to a threshold. The anomaly diagnosing process is a process of determining that an exhaust purification device is in a detached state when it is determined in the determination process that the deviation is less than or equal to the threshold. The first change amount and the second change amount are change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively.

Abstract: A controller for an internal combustion engine is configured to execute a regeneration process of burning and removing particulate matter accumulated in an exhaust purification device, a determination process of determining that a deviation between a first change amount and a second change amount is less than or equal to a threshold, the first change amount and the second change amount being change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively, and an anomaly diagnosing process that determines that the exhaust purification device is in a detached state when the determination process determines that the deviation is less than or equal to the threshold. The controller is configured to not execute the determination process during a period from the end of the regeneration process to when a post-regeneration execution condition is met.

Abstract: A controller for an internal combustion engine is configured to execute a determination process and an anomaly diagnosing process. The determination process is a process of determining that a deviation between a first change amount and a second change amount during a fuel cutoff operation is less than or equal to a threshold. The anomaly diagnosing process is a process of determining that an exhaust purification device is in a detached state when it is determined in the determination process that the deviation is less than or equal to the threshold. The first change amount and the second change amount are change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively.

Abstract: A controller for an internal combustion engine is configured to execute a determination process that determines that a deviation between a first change amount and a second change amount during a fuel cutoff operation is less than or equal to a threshold, and an anomaly diagnosing process that determines that an exhaust purification device is in a detached state when the determination process determines that the deviation is less than or equal to the threshold. The first change amount and the second change amount are change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively. The controller is configured to interrupt the determination process when the upstream-side temperature increases within a determination period.

Abstract: A controller for an internal combustion engine is configured to execute a regeneration process of burning and removing particulate matter accumulated in an exhaust purification device, a determination process of determining that a deviation between a first change amount and a second change amount is less than or equal to a threshold, the first change amount and the second change amount being change amounts per unit time of the temperature of exhaust gas on the upstream side and the downstream side of the exhaust purification device, respectively, and an anomaly diagnosing process that determines that the exhaust purification device is in a detached state when the determination process determines that the deviation is less than or equal to the threshold. The controller is configured to not execute the determination process during a period from the end of the regeneration process to when a post-regeneration execution condition is met.

Abstract: A control device of an internal combustion engine according to the present invention executes air-fuel ratio control based on an output of an air-fuel ratio sensor provided at an upstream side of a catalyst, with correction based on an output of an oxygen sensor at a downstream side of the catalyst. When it is determined that a degree of an output tendency in a predetermined lean region is not less than a predetermined lean degree, and that a degree of an output tendency in a predetermined rich region is less than a predetermined rich degree based on lean tendency and rich tendency values representing output tendencies of the oxygen sensor, a limit is set to the correction in a direction to more suppress enriching of an air-fuel ratio as a degree is larger in which the output of the oxygen sensor is shifted to a lean side.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine is provided. A controller is programmed to perform correction amount guard control allowing adjustment of a correction amount by setting a limit on the correction amount when an appearance frequency of a state where an output value from a downstream sensor is leaner than a predetermined value is equal to or higher than a predetermined value. When a state where the output value from the downstream sensor is leaner than the predetermined value lasts for a duration equal to or longer than a predetermined time, an incorporation speed at which, during learning control, the correction amount for sub feedback control is incorporated into a learning value is set to a larger value that when the duration is shorter than the predetermined time, and performance of the correction amount guard control is suppressed until the learning control is completed.

Abstract: A fuel injection amount control apparatus comprises an air-fuel ratio sensor disposed between an exhaust gas merging portion and an upstream catalyst. The control apparatus performs a feedback correction on an amount of fuel to be injected by the fuel injection valve so that an air-fuel ratio represented by the output value of the upstream air-fuel ratio sensor becomes equal to a target air-fuel ratio set at stoichiometric air-fuel ratio. The control apparatus obtains an air-fuel ratio imbalance indicating value, which becomes larger as a difference in air-fuel ratio of each of the mixtures supplied to each of the combustion chambers among the cylinders becomes larger, and performs an increasing correction to the instructed fuel injection amount in such a manner that an air-fuel ratio determined by the instructed fuel injection amount becomes richer than the stoichiometric air-fuel ratio as the obtained air-fuel ratio imbalance indicating value increases.

Abstract: An abnormality detecting device of an internal combustion engine according to the present invention includes a sensor nick abnormality detecting unit configured to detect a nick abnormality in a detecting element of a downstream side sensor which is provided in a downstream side of an exhaust gas purifying catalyst in an exhaust passage and generates an output corresponding to an oxygen concentration in exhaust gas, on the basis of a matter that a distribution of an output of the downstream side sensor is biased to an area in which the air-fuel ratio is leaner than a theoretical air-fuel ratio, and an inhibiting unit configured to inhibit detection of the nick abnormality of the detecting element by the sensor nick abnormality detecting unit in the case that an intake air amount exceeds a predetermined amount.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine is provided. A controller is programmed to perform correction amount guard control allowing adjustment of a correction amount by setting a limit on the correction amount when an appearance frequency of a state where an output value from a downstream sensor is leaner than a predetermined value is equal to or higher than a predetermined value. When a state where the output value from the downstream sensor is leaner than the predetermined value lasts for a duration equal to or longer than a predetermined time, an incorporation speed at which, during learning control, the correction amount for sub feedback control is incorporated into a learning value is set to a larger value that when the duration is shorter than the predetermined time, and performance of the correction amount guard control is suppressed until the learning control is completed.

Abstract: A control device of an internal combustion engine according to the present invention executes air-fuel ratio control based on an output of an air-fuel ratio sensor provided at an upstream side of a catalyst, with correction based on an output of an oxygen sensor at a downstream side of the catalyst. When it is determined that a degree of an output tendency in a predetermined lean region is not less than a predetermined lean degree, and that a degree of an output tendency in a predetermined rich region is less than a predetermined rich degree based on lean tendency and rich tendency values representing output tendencies of the oxygen sensor, a limit is set to the correction in a direction to more suppress enriching of an air-fuel ratio as a degree is larger in which the output of the oxygen sensor is shifted to a lean side.

Abstract: A control device of an internal combustion engine according to the present invention has units configured to inject fuel at a first predetermined ratio from first and second fuel injection valves which are provided in each of cylinders to calculate a first value indicating a degree of variation in air-fuel ratios between the cylinders based on a output of the engine, and inject fuel at a second predetermined ratio therefrom to calculate a second value in the same manner. Furthermore, the control device has a unit configured to select one mode from modes relating to abnormality in the first fuel injection valve or the second fuel injection valve on the basis of the first and second values, and calculate a value indicating the degree of the variation in the air-fuel ratios between the cylinders, thereby calculating a fuel amount of the basis of them.

Abstract: An inter-cylinder air-fuel ratio variation abnormality detection apparatus is disclosed. The apparatus determines imbalance of an air-fuel ratio among the cylinders based on a difference between index values correlated with crank angular velocities detected in a set of opposite cylinders belonging to different banks and having crank angles different from one another by 360°; and carries out an air-fuel ratio feedback process for controlling an amount of injected fuel for each of the banks, wherein the apparatus comprises a correction unit correcting, before determining the air-fuel ratio imbalance, the difference between the index values in a direction of combustion improvement for opposite cylinders that are opposite to cylinders belonging to a bank identical to a bank of a cylinder with the most deviating index value from a standard value among all the cylinders and being other than the cylinder with the most deviating index value.

Abstract: An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine according to the present invention increases a fuel injection quantity to a predetermined target cylinder to detect imbalance abnormality in an air-fuel ratio between cylinders at least based upon a rotation variation of the target cylinder after increasing the fuel injection quantity. The increase in the fuel injection quantity is carried out in the middle of performing the post-fuel-cut rich control. Since timing of the post-fuel cut rich control is used to increase the fuel injection quantity, the exhaust emission deterioration due to abnormality detection execution can be prevented as much as possible.

Abstract: A control device of an internal combustion engine according to the present invention has units configured to inject fuel at a first predetermined ratio from first and second fuel injection valves which are provided in each of cylinders to calculate a first value indicating a degree of variation in air-fuel ratios between the cylinders based on a output of the engine, and inject fuel at a second predetermined ratio therefrom to calculate a second value in the same manner. Furthermore, the control device has a unit configured to select one mode from modes relating to abnormality in the first fuel injection valve or the second fuel injection valve on the basis of the first and second values, and calculate a value indicating the degree of the variation in the air-fuel ratios between the cylinders, thereby calculating a fuel amount of the basis of them.

Abstract: An abnormality detecting device of an internal combustion engine according to the present invention includes a sensor nick abnormality detecting unit configured to detect a nick abnormality in a detecting element of a downstream side sensor which is provided in a downstream side of an exhaust gas purifying catalyst in an exhaust passage and generates an output corresponding to an oxygen concentration in exhaust gas, on the basis of a matter that a distribution of an output of the downstream side sensor is biased to an area in which the air-fuel ratio is leaner than a theoretical air-fuel ratio, and an inhibiting unit configured to inhibit detection of the nick abnormality of the detecting element by the sensor nick abnormality detecting unit in the case that an intake air amount exceeds a predetermined amount.

Abstract: Provided is an apparatus for detecting cylinder air-fuel ratio imbalance abnormality. The apparatus is provided with an abnormality detecting unit that detects a cylinder air-fuel ratio imbalance abnormality by comparing a value of a parameter correlated with a degree of fluctuation in the air-fuel ratio sensor output to an abnormality threshold value, and a correcting unit that corrects at least one of the value of the parameter or the abnormality threshold value on the basis of atmospheric pressure. An amount of correction performed by the correcting unit is modified according to engine load.

Abstract: An inter-cylinder air-fuel ratio variation abnormality detection apparatus is disclosed. The apparatus determines imbalance of an air-fuel ratio among the cylinders based on a difference between index values correlated with crank angular velocities detected in a set of opposite cylinders belonging to different banks and having crank angles different from one another by 360°; and carries out an air-fuel ratio feedback process for controlling an amount of injected fuel for each of the banks, wherein the apparatus comprises a correction unit correcting, before determining the air-fuel ratio imbalance, the difference between the index values in a direction of combustion improvement for opposite cylinders that are opposite to cylinders belonging to a bank identical to a bank of a cylinder with the most deviating index value from a standard value among all the cylinders and being other than the cylinder with the most deviating index value.