A system may include a NO.sub.x sensor and a controller. The controller may be configured to interpret a value of a first parameter indicative of an amount of NO.sub.x measured by the NO.sub.x sensor and interpret a value of a second parameter for a NO.sub.x value from a look-up table. The controller may be further configured to determine a correction factor based on the value of the first parameter and the value of the second parameter and generate a dosing command based, at least in part, on the determined correction factor. In some implementations, the NO.sub.x value from the look-up table may be based on one or more operating conditions of an engine. In some implementations, the controller may be further configured to update a NO.sub.x value of the look-up table based on the determined correction factor.

Methods and systems are provided for diagnosing a gasoline particulate filter in an engine exhaust passage. A pressure-flow relationship of the filter is learned in a low engine speed and high engine speed range. Degradation of the filter is identified based on a substantial separation between the curve fits at the high and low speed range.

A rich-wait-time threshold value is set based on the NOx discharge amount per unit time discharged from an internal combustion engine. When the elapsed time, i.e. either the elapsed engine operation time since rich control was performed on a lean NOx trap catalyst device, or the elapsed engine operation time since the engine was started, becomes equal to or greater than the rich-wait-time threshold value, a determination that the rich control be started is added as a necessary condition for starting the rich control. Accordingly, an exhaust gas purification system for an internal combustion engine, an internal combustion engine, and an exhaust gas purification method for an internal combustion engine are provided, with which the execution timing of the rich control for recovering the NOx occlusion capacity of the lean NOx trap catalyst device is rendered more appropriate, and thus NOx reduction is performed with little fuel consumption deterioration.

In the abnormality diagnosis device which carries out an abnormality diagnosis of the reducing agent adding device by obtaining a diagnostic parameter which is a parameter correlated with an amount of pressure drop in a reducing agent passage in the case where, from a state in which an addition valve has been closed and in which a voltage to be applied to a pump is controlled to a diagnostic voltage so that the pressure in the reducing agent passage becomes a predetermined pressure, the addition valve is made to open in a state where the voltage to be applied to the pump is maintained at the diagnostic voltage, and by making a comparison between the diagnostic parameter and a predetermined threshold value, the abnormality diagnosis is carried out by using the diagnostic parameter or the predetermined threshold value which is corrected based on the pump discharge capacity of the pump.

A PM amount estimation device is applied to a filter that collects PM in the exhaust gas discharged to an exhaust passage of an internal combustion engine. A storage device stores mapping data which is data defining a mapping that outputs the PM amount collected by the filter. The mapping has at least one of an intake air temperature variable and a wall surface variable, and a flow rate variable as inputs. The intake air temperature variable relates to the temperature of air drawn into the engine. The wall surface variable relates to a cylinder wall surface temperature of the engine. The flow rate variable indicates the flow rate of the fluid entering the filter. The execution device calculates the PM amount based on the output of the mapping having the acquired data as an input.

A system for controlling emissions of a motor-vehicle spark-ignition internal combustion engine includes first and second exhaust gas treatment devices and a secondary air feeding system for feeding secondary air into an exhaust gas conduit, between the first and second exhaust gas treatment devices. The secondary air feeding system is activated only when engine load is greater than a predetermined load value and/or when engine rotational speed is greater than a predetermined speed value. In this condition, an air/fuel ratio of the engine is kept at a value lower than the stoichiometric value, so as to feed the engine with a rich mixture. In one example, an electronic controller is configured for controlling activation of the secondary air feeding system on the basis of a map, as a function of values of the engine load and rotational speed. The map is predetermined depending upon specific characteristics of the engine.

A reductant delivery system for an internal combustion engine is arranged to inject a reductant into the exhaust aftertreatment system upstream of a catalytic device. A method for controlling the reductant delivery system includes operating the fluidic pump at a preset state, operating the injector at a zero-flow state, and monitoring, via a pressure sensor, a pressure in the reductant delivery system upstream of the injector to determine a zero-flow pressure. The injector is activated under a preset condition and an actual pressure drop upstream of the injector is monitored. A pressure drop deviation is determined based upon the actual pressure drop upstream of the injector and an expected pressure drop upstream of the injector. An adjustment to the activation of the injector is determined based upon the pressure drop deviation, and the injector is controlled based upon the adjustment.

In a method for the regeneration of a particulate filter or of a four-way catalytic converter in an exhaust system of an internal combustion engine, an increase in the nitrogen oxide emissions during the regeneration of the particulate filter or of the four-way catalytic converter can be prevented or at least reduced. A particulate filter or a four-way catalytic converter is arranged in the exhaust system of an internal combustion engine. The fuel injection and the ignition are switched off in response to a request for the internal combustion engine to be turned off. Due to mass inertia, the internal combustion engine transitions from the switch-off rotational speed to a standstill whereby, during this phase, oxygen-rich air is conveyed into the exhaust passage. A partial regeneration of the filter or of the catalytic converter takes place with the oxygen contained in this fresh air, whereby the particulate mass discharged from the filter or the catalytic converter is determined by means of a computational model.

A method for operating an exhaust gas post-treatment system of a diesel engine and associated exhaust gas post-treatment system are described. The system has two NOx sensors upstream and downstream of an SCR catalytic converter. The NOx sensor downstream of the SCR catalytic converter is used to divide the NOx information measured by the sensor upstream of the SCR catalytic converter into an NOx value and an NH.sub.3 value. Using this simple method, the SCR catalyst control and diagnosis can be carried out precisely and robustly.

The present invention relates to a method for analysing the operation of an anti-pollution system for a motor vehicle (1) with an internal combustion engine, said vehicle (1) comprising at least one sensor for measuring (110) a parameter of the vehicle (1) and an analysis computation means (140) directly connected to said measuring sensor (110), said analysis computation means (140) comprising a memory area, said method being characterised in that it comprises a step for using the measuring sensor (110) to measure at least one parameter of the vehicle (1), a step for using the measuring sensor (110) to transmit at least one digital datum representative of the measured value of the parameter to the analysis computation means (140) and a step for using the analysis computation means (140) to compare said digital datum with a predetermined range of values representative of an operation of the anti-pollution system according to a predetermined standard.