Abstract: Various methods are provided for diagnosing an exhaust fluid sensor disposed in an exhaust fluid passage. By monitoring the sensor during conditions when it is in contact with the exhaust fluid and when it is not in contact with the exhaust fluid, an expected change in the sensor output can be monitored to identify whether the sensor is generating sufficiently accurate readings.

Abstract: Various systems and methods for detecting exhaust reductant injector degradation based on an exhaust NOx sensor are disclosed. In one example, degradation of the reductant injector is indicated when an actual NOx sensor output differs from an expected NOx sensor output by more than a threshold amount under engine off conditions.

Abstract: Methods and systems are provided for adjusting a LP-EGR valve and an LP intake throttle to provide a desired LP-EGR flow rate while maintaining a minimum differential pressure. In one example, a method for a turbocharged engine method comprises: responsive to a differential between intake and exhaust pressure below a threshold, adjusting a LP-EGR valve while adjusting a LP intake throttle to regulate a LP-EGR flow rate and the differential to respective setpoints; and responsive to the differential above the threshold, saturating the LP-EGR valve to minimize the differential while actuating the throttle to regulate the flow rate to its setpoint. In this way, control of the LP-EGR system may be more robust to disturbances at very low differential pressures, require less actuator movement, and increase fuel economy.

Abstract: A method for controlling a particulate matter sensor heater is provided. The method includes operating the heater to burn-off soot accumulated on the sensor; and adjusting the heater level based on sensor output generated during the heater operation. In this way, improved heater control can be achieved using the sensor output already available.

Abstract: A method for determining soot mass oxidized during a particulate filter oxidation procedure is disclosed. In one example, soot mass is determined via an Arrhenius equation. The approach may provide cost savings and reliability improvements as compared to other ways of determining soot mass.

Abstract: A method and system is provided for correlating a pressure drop across an exhaust particulate filter with the output of an upstream exhaust oxygen sensor and a downstream exhaust oxygen sensor. The pressure drop is then used to infer leakage of the filter during conditions when an exhaust oxygen concentration across the filter is substantially constant. The diagnostic may be performed during selected entry conditions such as when a particulate level in the GPF is below a predetermined threshold, exhaust flow rate is above a threshold rate, and an absolute exhaust flow rate derivative is below a threshold derivative.

Abstract: A method for diagnosing a particulate matter sensor is described. In one example, a liquid is purposefully injected into the exhaust system to verify operation of the particulate matter sensor. Reliability of particulate matter diagnostics may be improved by way of the approach, at least during some conditions.

Abstract: A method to control a hybrid electric vehicle includes operating a compression ignition engine based on an engine-on request, and performing an exhaust aftertreatment procedure when a fraction of an engine-on time is greater than an aftertreatment condition threshold. A vehicle has a compression ignition engine with an exhaust aftertreatment system, and a controller. The controller is configured to: (i) operate the engine based on an engine-on request, and (ii) perform an exhaust aftertreatment procedure for the vehicle when an engine-on fraction for a designated time is greater than an aftertreatment condition threshold. A computer readable medium having stored data representing instructions executable by a controller to control a vehicle includes instructions for operating the engine based on an engine-on request, and instructions for performing an exhaust aftertreatment procedure for the vehicle when an engine-on time fraction is greater than an aftertreatment condition threshold.

Abstract: A method for determining NH3 and NOx slippage through a SCR is described. In one example, signals from NOx sensors positioned upstream and downstream of a SCR are processed and provide indication of NH3 and NOx slippage. Engine emissions may be reduced with information provided via the NOx sensors, at least during some conditions.

Abstract: Methods and systems for controlling operation of exhaust of an engine including a particulate filter are provided. One example method includes generating vacuum during engine operation, and storing the vacuum. The method further includes, during or after engine shutdown, drawing ambient air through the particulate filter via the vacuum.

Abstract: A method for controlling combustion in an engine is provided. The method comprises under a first condition, adjusting an EGR amount of a total cylinder charge in response to engine out NOx levels being below a first threshold. In this way, NOx levels may be used as feedback to control combustion stability.

Abstract: Various systems and method for detecting exhaust NOx sensor degradation are disclosed. In one example, degradation of the NOx sensor is indicated responsive to reductant injection in an exhaust passage under engine off conditions. For example, degradation of the NOx sensor is indicated when an actual NOx sensor output differs from an expected NOx sensor output by more than a threshold amount.

Abstract: Various systems and methods for detecting exhaust reductant injector degradation based on an exhaust NOx sensor are disclosed. In one example, degradation of the reductant injector is indicated when an actual NOx sensor output differs from an expected NOx sensor output by more than a threshold amount under engine off conditions.

Abstract: The disclosure relates to a method and an observer for determining the exhaust manifold temperature in a turbocharged engine upstream of the turbine. In one example, a method for determining an exhaust manifold temperature in a turbocharged engine, the engine including a turbocharger and a turbine and the exhaust manifold temperature including a temperature upstream of the turbine, the method comprises estimating a value of the exhaust manifold temperature based on a model, measuring a temperature downstream of the turbine, and correcting the value of the exhaust manifold temperature based on the measurement.

Abstract: Various systems and method for detecting exhaust NOx sensor degradation are disclosed. In one example, degradation of the NOx sensor is indicated responsive to reductant injection in an exhaust passage under engine off conditions. For example, degradation of the NOx sensor is indicated when an actual NOx sensor output differs from an expected NOx sensor output by more than a threshold amount.

Abstract: Various systems and methods are described for controlling operation of a motor vehicle based on a sensor. One example method comprises receiving sensed parameter data from the sensor, receiving calibration data from the sensor, and adjusting a vehicle operating parameter in response to the sensed parameter data and the calibration data.

Abstract: A system for improving operation of an engine having a particulate matter sensor is presented. The system may be used to improve engine operation during cold starts especially under conditions where water vapor or entrained water droplets are present in vehicle exhaust gases. In one embodiment, particulate sensor degradation is indicated in response to an output of said particulate matter sensor staying below a threshold as engine temperature increases past the dewpoint temperature.

Abstract: Various systems and methods are described for detecting ammonia slip. In one example method, an amount of exhaust gas recirculation is reduced when output from an exhaust gas sensor indicates an increase in nitrogen oxide above a threshold amount. When the sensor output increases above a second threshold while the exhaust gas recirculation is reduced, the sensor output is allocated to nitrogen oxide; and when the sensor output does not increase above a second threshold while the exhaust gas recirculation is reduced, the sensor output is allocated to ammonia.

Abstract: Various systems and methods are described for managing ammonia storage in an SCR catalyst. In one example approach, a method comprises, in response to a vehicle-off event, injecting ammonia during a final exhaust blowdown until a predetermined value of ammonia is stored in the SCR catalyst; and in response to a subsequent vehicle-on event when an amount of ammonia stored in the SCR catalyst is less than the predetermined value, injecting ammonia until the predetermined value of ammonia is stored in the SCR catalyst.

Abstract: Methods are provided for determining an exhaust fluid level in an exhaust fluid storage tank based on a signal, and a quality of the signal from an exhaust fluid level sensor located in the exhaust fluid tank of a vehicle.