Provided is an exhaust purification system including: an NOx occlusion reduction type catalyst (32), a catalyst temperature estimating unit (115), an NOx occlusion amount estimating unit (113), a regeneration control unit (100) that performs catalyst regeneration of bringing an exhaust gas into a rich state to recover NOx occlusion capacity of the NOx occlusion reduction type catalyst (32), an interval setting unit (118) that sets a target interval from the termination of the catalyst regeneration to a start of next catalyst regeneration, a catalyst regeneration start processing unit (110) that starts the next catalyst regeneration when the NOx occlusion amount is equal to or greater than a threshold and an elapsed time from the termination of the catalyst regeneration reaches the target interval, and an interval target value correcting unit (119) that extends and corrects the target interval based on the NOx occlusion amount when the catalyst temperature is lower than a predetermined catalyst activation temperature.

Systems and methods for diagnosing at least one component in an exhaust aftertreatment system are provided. The system includes an exhaust aftertreatment system coupled to an engine system, at least one sensor, and at least one processing circuit structured to: receive initial sensor data; determine an initial parameter value based on the initial sensor data; determine that the initial parameter does not satisfy an initial threshold; perform operations to diagnose at least one component of the exhaust aftertreatment system comprising: causing the engine system to operate through a sequence of a plurality of engine outputs; receiving a plurality of sensor data, each of the plurality sensor data corresponding to at least one of the plurality of engine outputs; comparing each of the plurality of sensor data to a corresponding threshold; and diagnosing the at least one component based on the comparison.

Rich control is performed to hold an air-fuel ratio of an exhaust gas discharged from an engine combustion chamber temporarily richer than the stoichiometric air-fuel ratio by injecting additional fuel into a cylinder in an expansion stroke or exhaust stroke while an exhaust gas recirculation rate is made lower than a base exhaust gas recirculation rate. A variable valve timing mechanism able to change an overlap period is provided. When ending rich control (ta2), the injection of additional fuel is stopped and the overlap period (OL) is increased from a base overlap period (OLB) and held there while an EGR rate (REGR) is kept lower than a base EGR rate (REGRB) and when a delay time (dt) elapses, the EGR rate and the overlap period are reset to the base EGR rate and the base overlap period.

A method and a unit for operating or for the operation of a fuel metering system of an internal combustion engine, in particular in a motor vehicle, and it being provided, in particular, that at least one operating variable of the internal combustion engine is detected, a dynamic operating state of the internal combustion engine is detected based on the at least one detected operating variable, and a dynamic correction to the fuel metering system of the internal combustion engine is carried out for a detected dynamic operating state of the internal combustion engine, taking into account the efficiency of an NOx exhaust gas aftertreatment system.

A method is disclosed for operating an automotive system having an internal combustion engine equipped with an exhaust gas aftertreatment system including a Lean NO.sub.x Trap (LNT) upstream of a Selective Catalytic Reduction washcoated particulate filter (SCRF). A LNT inlet temperature is monitored. A parameter representative of a quantity of NO.sub.X stored in the LNT is also monitored. A map correlating the LNT inlet temperature and the quantity of NO.sub.X stored in the LNT is used to estimate an ammonia quantity produced during a LNT regeneration. A LNT regeneration is performed, if the estimated ammonia quantity is greater than a threshold value thereof.

Systems and methods for diagnosing at least one component in an exhaust aftertreatment system are provided. The system includes an exhaust aftertreatment system coupled to an engine system, at least one sensor, and at least one processing circuit structured to: receive initial sensor data; determine an initial parameter value based on the initial sensor data; determine that the initial parameter does not satisfy an initial threshold; perform operations to diagnose at least one component of the exhaust aftertreatment system comprising: causing the engine system to operate through a sequence of a plurality of engine outputs; receiving a plurality of sensor data, each of the plurality sensor data corresponding to at least one of the plurality of engine outputs; comparing each of the plurality of sensor data to a corresponding threshold; and diagnosing the at least one component based on the comparison.

Provided is an exhaust purification system including: an NOx occlusion reduction type catalyst (32), a catalyst temperature estimating unit (115), an NOx occlusion amount estimating unit (113), a regeneration control unit (100) that performs catalyst regeneration of bringing an exhaust gas into a rich state to recover NOx occlusion capacity of the NOx occlusion reduction type catalyst (32), an interval setting unit (118) that sets a target interval from the termination of the catalyst regeneration to a start of next catalyst regeneration, a catalyst regeneration start processing unit (110) that starts the next catalyst regeneration when the NOx occlusion amount is equal to or greater than a threshold and an elapsed time from the termination of the catalyst regeneration reaches the target interval, and an interval target value correcting unit (119) that extends and corrects the target interval based on the NOx occlusion amount when the catalyst temperature is lower than a predetermined catalyst activation temperature.

Methods and systems are provided for reducing engine cold-start emissions. An exhaust system having a passive NOx adsorber (PNA) may store NOx during an engine cold-start until conditions are optimal for release of the stored NOx to a downstream SCR catalyst. Based on PNA conditions, including a NOx load and a PNA bed temperature, adjustments to EGR rate and/or injection timing may be made to achieve a catalytically favorable ratio of NOx species upstream of the SCR catalyst, after the SCR catalyst has reached its light-off temperature.

An engine diagnostic tool includes a diagnostic engine calibration module structured to include a plurality of diagnostic processes for operating an internal combustion engine system of an immobilized vehicle. One or more of the plurality of diagnostic processes are structured to be an intrusive diagnostic process for the internal combustion engine system, wherein the intrusive diagnostic process causes the internal combustion engine system to operate outside of one or more calibration parameters. The diagnostic engine module is further structured to control the order and timing of each diagnostic process in the plurality of diagnostic processes.

An engine diagnostic tool includes a diagnostic engine calibration module structured to include a plurality of diagnostic processes for operating an internal combustion engine system of an immobilized vehicle. One or more of the plurality of diagnostic processes are structured to be an intrusive diagnostic process for the internal combustion engine system, wherein the intrusive diagnostic process causes the internal combustion engine system to operate outside of one or more calibration parameters. The diagnostic engine module is further structured to control the order and timing of each diagnostic process in the plurality of diagnostic processes.