A system includes an engine comprising an EGR valve that recirculates a portion of exhaust gas, a data repository that stores a first look up and one or more engine operational parameters, an engine control unit operationally coupled to the engine and the data repository, wherein the engine control unit is configured to: determine a desired EGR flow rate reference of the portion of the exhaust gas based on the one or more engine operational parameters and the first look up table, determine a current estimated EGR flow rate based on the one or more engine operational parameters, determine a designated corrected EGR flow rate reference based on the desired EGR flow rate reference and a delta EGR flow rate, determine EGR flow rate error, and determine a percentage opening of the EGR valve based at least on the EGR flow rate error.

A method and system for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one example, the method determines an estimate of an exhaust gas oxygen sensor time constant according to a comparison of air/fuel ratios and a system time constant.

Methods are provided for identifying degradation in components of a compressor recirculation valve (CRV). One method may include inferring degradation of the CRV based on adaptation of a compressor surge line outside an expected range.

Methods and systems are provided for adjusting a throttle based on an intake oxygen sensor output. In one example, a method may include adjusting a position of a throttle based on a dilution threshold and a total aircharge dilution level, the total dilution aircharge level based on an output of an intake oxygen sensor. Additionally, spark timing may be adjusted based on the total aircharge dilution level.

An engine control system is provided and includes an engine having combustion chambers and provides driving torque through combustion of a fuel injected into the combustion chambers. A turbocharger includes a turbine rotated according to flow energy of exhaust gas, a compressor compressing external air, and a vane adjusting amount of exhaust gas supplied to the turbine. An EGR device recirculates exhaust gas to the combustion chamber. An exhaust manifold includes a body with an internal fluid path, exhaust inlets in which exhaust gas is introduced, a partition to form internal fluid paths, and an exhaust outlet to which exhaust gas is exhausted. Temperature sensors measure temperature of exhaust gas flowing through the internal fluid paths. A controller adjusts an opening amount of the vane of the turbocharger, exhaust gas recirculated using the EGR device, and fuel to be injected to the combustion chambers based on measured temperature.

An exhaust gas recirculation apparatus including an engine; a suction line; an exhaust line; a post-processing unit which is disposed in the exhaust line to reduce hazardous substances contained in the exhaust gas; a first circulation line which guides a part of the exhaust gas, which is guided to the exhaust line, to the suction line; a second circulation line which guides a part of the exhaust gas, which is guided to a downstream side of the post-processing unit, to the suction line; and a bypass line which branches off from an upstream side of the second circulation line, and merges with a downstream side of the second circulation line, wherein ammonia slip, which is discharged from the post-processing unit, is prevented from being guided to the suction line.

Methods and systems are provided for adjusting a throttle based on an intake oxygen sensor output. In one example, a method may include adjusting a position of a throttle based on a dilution threshold and a total aircharge dilution level, the total dilution aircharge level based on an output of an intake oxygen sensor. Additionally, spark timing may be adjusted based on the total aircharge dilution level.

Various method for operating an engine responsive to transmission shifts under non-fueling conditions are provided. In one example, a method of operating an internal combustion engine comprises deactivating at least one engine cylinder, performing a diagnostic while the at least one engine cylinder is deactivated and while the engine is operating under high load, predicting a transmission shift, and responsive to the predicted transmission shift, reducing engine load below the high load and terminating the diagnostic.

A control device for an engine provided with a turbocharger properly uses a parameter used for controlling a center-of-gravity position of a heat generation rate determined by a heat generation rate as the amount per unit crank angle of heat generated by combustion of fuel depending on operating situations of the engine and a vehicle in which the engine is mounted. Specifically, an increase in a turbocharging pressure of the turbocharger is executed when a rotational speed of the engine and a speed of the vehicle in which the engine is mounted are lower than predetermined reference values in a case where the center-of-gravity position of a heat generation rate is further on a retard side than a predetermined crank angle and one or both of an increase in a fuel injection pressure and advancing of a fuel injection timing are executed when the rotational speed of the engine or the speed of the vehicle in which the engine is mounted are equal to or higher than the predetermined reference values in the case where the center-of-gravity position of a heat generation rate is further on the retard side than the predetermined crank angle. Then, fuel economy can be improved by the center-of-gravity position of a heat generation rate being maintained at a predetermined fixed value regardless of a load of the engine and/or the engine rotational speed while an increase in noise and vibration a user feels uncomfortable with is suppressed.

An exhaust gas recirculation apparatus including an engine; a suction line; an exhaust line; a post-processing unit which is disposed in the exhaust line to reduce hazardous substances contained in the exhaust gas; a first circulation line which guides a part of the exhaust gas, which is guided to the exhaust line, to the suction line; a second circulation line which guides a part of the exhaust gas, which is guided to a downstream side of the post-processing unit, to the suction line; and a bypass line which branches off from an upstream side of the second circulation line, and merges with a downstream side of the second circulation line, wherein ammonia slip, which is discharged from the post-processing unit, is prevented from being guided to the suction line.