Patent application number | Description | Published |
20090120061 | Hydrocarbon Retaining and Purging System - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090120063 | Hydrocarbon Retaining System Configuration for Combustion Engine - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090120064 | Engine Starting Control for Engine with Hydrocarbon Retaining System - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090120065 | Hydrocarbon Retaining and Purging System for Flex-Fuel Combustion Engine - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090120067 | Hydrocarbon Retaining System and Method - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090120071 | Hydrocarbon Retaining System for Flex-Fuel Combustion Engine - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 05-14-2009 |
20090182488 | Temperature Sensor Diagnostics - A system for an internal combustion engine of a vehicle includes an emission control device in an exhaust stream of the engine; an exhaust gas oxygen sensor coupled upstream of the emission control device; a temperature sensor coupled adjacent the emission control device; and a controller coupled to the exhaust gas oxygen sensor and the temperature sensor, the controller identifying degradation of the temperature sensor responsive to the exhaust gas oxygen sensor during lean operation, where the controller operates the exhaust gas oxygen sensor in a temperature sensing mode to identify the degradation of the temperature sensor. | 07-16-2009 |
20100024396 | HYDROCARBON RETAINING AND PURGING SYSTEM - Method and systems are provided for operating an engine having a hydrocarbon retaining system coupled to an engine exhaust and an engine intake. One example method comprises, during an engine cold start, routing exhaust gas to the hydrocarbon retaining system to store hydrocarbons in the hydrocarbon retaining system. The method further comprises, during a first purging condition where the exhaust gas is at a first temperature, purging the hydrocarbon retaining system with at least exhaust gas, and during a second purging condition where the exhaust gas is at a second temperature, said second temperature being higher than said first temperature, mixing the exhaust gas with an amount of fresh air to form a purging gas mixture, and purging the hydrocarbon retaining system with said purging gas mixture. | 02-04-2010 |
20100223921 | HYDROCARBON RETAINING AND PURGING SYSTEM - Methods and systems are provided for operating an engine having a hydrocarbon retaining system and an emission control device coupled to an engine exhaust, the engine exhaust comprising a venturi. One example method comprises, during a storing condition, routing exhaust gas through the venturi without generating a venturi action, and then to the hydrocarbon retaining system, while bypassing the emission control device, to store hydrocarbons in the hydrocarbon retaining system, and during a purging condition, routing exhaust gas through the venturi while generating venturi action, then to the emission control device, and then to the hydrocarbon retaining system, to purge stored hydrocarbons, wherein a flow of purged hydrocarbons is drawn back to the venturi via venturi action. | 09-09-2010 |
20100263639 | Engine Control Method and System - Methods and systems are provided for operating a vehicle engine including an intake and an exhaust, the engine further including a boosting device configured to provide a boosted air charge to the engine intake. One example method comprises, during an engine cold start, operating the engine with positive intake to exhaust valve overlap, driving a compressor of the boosting device at least partially via a motor to generate blow-through air flow into the engine exhaust through cylinders of the engine, and exothermically reacting a reductant with the blow-through air flow in the exhaust. | 10-21-2010 |
20100300405 | Approach for Controlling a Vehicle Engine That Includes an Electric Boosting Device - A method of operating a vehicle including an engine is provided The engine may include at least one cylinder, a boosting device to boost intake air to the at least one cylinder, a fuel tank, a fuel vapor canister to store fuel vapors vented from the fuel tank, and an emission control device to treat exhaust gas from the engine. The boosting device includes a compressor at least partially driven by an electric motor. The method includes during an engine cold start condition, operating the electric motor of the boost device to boost intake air, directing the boosted intake air through the fuel vapor canister to release a fuel vapor stored in the fuel vapor canister, directing the fuel vapor from the fuel vapor canister to the engine, and performing combustion in the at least one cylinder using the fuel vapor during the engine starting. | 12-02-2010 |
20110061371 | HYDROCARBON AND NOx TRAP - A hydrocarbon and NOx trap and related apparatus and methods for reducing cold-start NOx emissions from an engine are provided. In one embodiment a trap includes a first, topmost layer, exposed to an exhaust gas flow path of exhaust gases from an engine, the first layer comprising a zeolite, a second layer, substantially covered by the top most layer, the second layer comprising a NOx adsorbing material and a monolithic substrate, directly supporting the second layer and indirectly supporting the first layer, the substrate providing a substantially rigid structure of the trap. | 03-17-2011 |
20110072801 | EXHAUST TREATMENT SYSTEM FOR INTERNAL COMBUSTION ENGINE - Methods and systems are provided for operating an engine including an exhaust treatment system coupled to an engine exhaust, the exhaust treatment system further coupled to an engine intake via an exhaust gas recirculation (EGR) system. One example method comprises, operating in a first mode including routing exhaust gas through the exhaust treatment system to an exhaust tailpipe; operating in a second mode including routing exhaust gas through the exhaust treatment system to an engine intake via the EGR system, and operating in a third mode including routing exhaust gas to an engine intake through the EGR system while bypassing the exhaust treatment system. | 03-31-2011 |
20110132337 | EXHAUST TREATMENT SYSTEM FOR INTERNAL COMBUSTION ENGINE - Systems and methods are provided for operating an engine exhaust system. In one example, a system comprises a first valve, and a second valve coupled to the first valve via a shaft. A first position of the shaft situates the first valve closed and the second valve open, a second position situates the second valve closed and the first valve open by a first amount, and a third position situates the second valve closed and the first valve open by a second, larger amount. | 06-09-2011 |
20110252794 | EXHAUST TREATMENT SYSTEM FOR INTERNAL COMBUSTION ENGINE - Systems and methods are provided for operating an engine exhaust system. In one example, a system comprises a first valve, and a second valve coupled to the first valve via a shaft. A first position of the shaft situates the first valve closed and the second valve open, a second position situates the second valve closed and the first valve open by a first amount, and a third position situates the second valve closed and the first valve open by a second, larger amount. | 10-20-2011 |
20110265453 | Methods and Systems for Variable Displacement Engine Control - Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection. | 11-03-2011 |
20110265454 | Methods and Systems for Variable Displacement Engine Control - Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection. | 11-03-2011 |
20110265771 | Methods and Systems for Variable Displacement Engine Control - Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection. | 11-03-2011 |
20120137659 | Hydrocarbon Retaining System Configuration for Combustion Engine - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 06-07-2012 |
20120204544 | HYDROCARBON RETAINING AND PURGING SYSTEM - Methods and systems are provided for operating an engine having a hydrocarbon retaining system and an emission control device coupled to an engine exhaust, the engine exhaust comprising a venturi. One example method comprises, during a storing condition, routing exhaust gas through the venturi without generating a venturi action, and then to the hydrocarbon retaining system, while bypassing the emission control device, to store hydrocarbons in the hydrocarbon retaining system, and during a purging condition, routing exhaust gas through the venturi while generating venturi action, then to the emission control device, and then to the hydrocarbon retaining system, to purge stored hydrocarbons, wherein a flow of purged hydrocarbons is drawn back to the venturi via venturi action. | 08-16-2012 |
20120227714 | Method and System for Humidity Sensor Diagnostics - Methods and systems are provided for an engine including a humidity sensor. Degradation of the humidity sensor may be determined based on a change in intake air relative humidity as compared to a change in intake air temperature or pressure, under selected conditions. An amount of exhaust gas recirculated to an engine intake is adjusted differently based on whether the humidity sensor is degraded or functional. | 09-13-2012 |
20120227719 | Method and System for Humidity Sensor Diagnostics - Methods and systems are provided for an engine including a humidity sensor. Degradation of the humidity sensor may be determined based on a change in intake air relative humidity as compared to a change in intake air temperature or pressure, under selected conditions. An amount of exhaust gas recirculated to an engine intake is adjusted differently based on whether the humidity sensor is degraded or functional. | 09-13-2012 |
20120265396 | Distinguishing Between EGR Valve and Oxygen Sensor Degradation - A diagnostic method for an engine having a valve for controlling dilution of intake air. The method comprises, during engine fueling, indicating a degradation of the valve when the valve is commanded closed but sensor output corresponds to an oxygen level below that of air. The method further comprises, absent engine fueling, indicating degradation of the sensor when the valve is commanded closed but the sensor output corresponds to an oxygen level below that of air. | 10-18-2012 |
20120285161 | Methods and Systems for Variable Displacement Engine Control - Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection. | 11-15-2012 |
20130006507 | Approach for Controlling a Vehicle Engine That Includes an Electric Boosting Device - A method of operating a vehicle including an engine is provided. The engine may include at least one cylinder, a boosting device to boost intake air to the at least one cylinder, a fuel tank, a fuel vapor canister to store fuel vapors vented from the fuel tank, and an emission control device to treat exhaust gas from the engine. The boosting device includes a compressor at least partially driven by an electric motor. The method includes during an engine cold start condition, operating the electric motor of the boost device to boost intake air, directing the boosted intake air through the fuel vapor canister to release a fuel vapor stored in the fuel vapor canister, directing the fuel vapor from the fuel vapor canister to the engine, and performing combustion in the at least one cylinder using the fuel vapor during the engine starting. | 01-03-2013 |
20130078725 | ENGINE CATALYST DIAGNOSTICS - Embodiments for predicting catalyst function are disclosed. One example embodiment includes applying a set of parameter readings for a given sample to a support vector machine to generate a classification output, recording a plurality of classification outputs for a plurality of successive samples over a first duration, and indicating catalyst degradation if a threshold percentage of the classification outputs indicates degraded catalyst performance. In this way, catalyst degradation may be indicated using a simplified model that does not require extensive calibration. | 03-28-2013 |
20130110376 | METHOD AND SYSTEM FOR ENGINE CONTROL | 05-02-2013 |
20130231844 | NON-INTRUSIVE EXHAUST GAS SENSOR MONITORING - A method for monitoring an exhaust gas sensor coupled in an engine exhaust is provided. In one embodiment, the method comprises indicating exhaust gas sensor degradation based on a time delay and line length of each sample of a set of exhaust gas sensor responses collected during a commanded change in air-fuel ratio. In this way, the exhaust gas sensor may be monitored utilizing robust parameters in a non-intrusive manner. | 09-05-2013 |
20130231847 | NON-INTRUSIVE EXHAUST GAS SENSOR MONITORING - Systems and methods for monitoring an exhaust gas sensor coupled in an engine exhaust are provided. In one example approach, a method comprises indicating exhaust gas sensor degradation based on a downstream exhaust gas sensor responding before the upstream exhaust gas sensor during a commanded change in air-fuel ratio. | 09-05-2013 |
20130245919 | LOW DIMENSIONAL THREE WAY CATALYST MODEL FOR CONTROL AND DIAGNOSTICS - Embodiments for an engine exhaust are provided. In one example, a method comprises adjusting a fuel injection amount based on a fractional oxidation state of a catalyst, the fractional oxidation state based on reaction rates of a plurality of exhaust gas species throughout a catalyst longitudinal axis and a set of axially-averaged mass balance and energy balance equations for a fluid phase and a washcoat of the catalyst. In this way, a simplified catalyst model may be used to control air-fuel ratio. | 09-19-2013 |
20130247544 | HYDROCARBON RETAINING AND PURGING SYSTEM FOR FLEX-FUEL COMBUSTION ENGINE - Systems, methods, and computer readable storage media are described in which exhaust gas is routed to a hydrocarbon retaining device during starting, and purged to the engine intake manifold. Various alternative approaches are described for controlling operation and diagnosing degradation. Further, various interrelated configurations are described. | 09-26-2013 |
20140026872 | VARIABLE VALVE TIMING FOR EGR CONTROL - Methods and systems are provided for adjusting cylinder valve timings to enable a group of cylinders to operate and combust while another group of cylinders on a second are selectively deactivated. Valve timing may be adjusted to allow flow of air through the inactive cylinders to be reduced, lowering catalyst regeneration requirements upon reactivation. The valve timing may alternatively be adjusted to enable exhaust gas to be recirculated to the active cylinders via the inactive cylinders, providing cooled EGR benefits. | 01-30-2014 |
20140032083 | VARIABLE VALVE TIMING FOR CYLINDER DEACTIVATION - Methods and systems are provided for adjusting cylinder valve timings to enable a group of cylinders to operate and combust while another group of cylinders on a second are selectively deactivated. Valve timing may be adjusted to allow flow of air through the inactive cylinders to be reduced, lowering catalyst regeneration requirements upon reactivation. The valve timing may alternatively be adjusted to enable exhaust gas to be recirculated to the active cylinders via the inactive cylinders, providing cooled EGR benefits. | 01-30-2014 |
20140039778 | NOX CONTROL DURING CYLINDER DEACTIVATION - Methods and systems are provided for improving engine exhaust emissions while enabling exhaust catalyst regeneration following an engine lean event. Prior to a VDE event, or prior to an engine idle-stop, ammonia is produced and stored on an exhaust underbody SCR catalyst. Then, during the engine restart after the VDE mode or the idle-stop, the stored ammonia is used to treat exhaust NOx species while an upstream exhaust underbody three-way catalyst is regenerated. | 02-06-2014 |
20140039781 | NOX CONTROL DURING ENGINE IDLE-STOP OPERATIONS - Methods and systems are provided for improving engine exhaust emissions while enabling exhaust catalyst regeneration following an engine lean event. Prior to a VDE event, or prior to an engine idle-stop, ammonia is produced and stored on an exhaust underbody SCR catalyst. Then, during the engine restart after the VDE mode or the idle-stop, the stored ammonia is used to treat exhaust NOx species while an upstream exhaust underbody three-way catalyst is regenerated. | 02-06-2014 |
20140123631 | METHODS AND SYSTEMS FOR VARIABLE DISPLACEMENT ENGINE CONTROL - Methods and systems are provided for selecting a group of cylinders for selective deactivation, in a variable displacement engine system, based at least on a regeneration state of an exhaust catalyst. The position of one or more valves and throttles may be adjusted based on the selective deactivation to reduce back-flow through the disabled cylinders while also maintaining conditions of a downstream exhaust catalyst. Pre-ignition and knock detection windows and thresholds may also be adjusted based on the deactivation to improve the efficiency of knock and pre-ignition detection. | 05-08-2014 |
20140144125 | SCR CATALYST DIAGNOSTICS - In one embodiment, a method for an engine comprises operating the engine with an upstream exhaust sensor, intermediate exhaust sensor, and downstream exhaust sensor each indicating rich, adjusting engine operation to operate the engine with an upstream exhaust sensor, intermediate exhaust sensor, and downstream exhaust sensor each indicating lean, adjusting engine operation to operate the engine with the upstream exhaust sensor indicating rich and the intermediate and downstream exhaust sensors each indicating lean, and indicating degradation of an SCR catalyst based on when the intermediate and downstream exhaust sensors switch from lean to rich. | 05-29-2014 |
20140238348 | HUMIDITY SENSOR DIAGNOSTICS - Embodiments for diagnosing a humidity sensor are provided. One example method comprises, responsive to a humidity sensor test cycle, pumping air conditioning and windshield washer gas flows past a humidity sensor, and indicating humidity sensor degradation based on a response of the humidity sensor to the air conditioning and windshield washer gas flows. In this way, degradation of the humidity sensor may be indicated if the humidity sensed by the humidity sensor does not change responsive to the humidity sensor test cycle being initiated. | 08-28-2014 |
20140238368 | EXHAUST GAS SENSOR DIAGNOSIS AND CONTROLS ADAPTATION - Methods and systems are provided for adjusting an anticipatory controller of an exhaust gas sensor coupled in an engine exhaust. In one embodiment, the method comprises adjusting fuel injection responsive to exhaust oxygen feedback from the anticipatory controller of the exhaust gas sensor and adjusting one or more parameters of the anticipatory controller responsive to a type of oxygen sensor degradation. In this way, the anticipatory controller may be adapted based on the type and magnitude of the degradation behavior to increase performance of the air-fuel control system. | 08-28-2014 |
20140238369 | HUMIDITY SENSOR DIAGNOSTICS - Embodiments for testing a humidity sensor are provided. One example method comprises indicating degradation of a humidity sensor based on a humidity sensor output and output from an intake gas composition sensor. In this way, output from the intake gas composition sensor may be used to determine if the humidity sensor is degraded. | 08-28-2014 |
20140238370 | HUMIDITY SENSOR DIAGNOSTICS - Embodiments for diagnosing a humidity sensor are provided. One example method comprises adjusting an engine operating parameter based on humidity of a first gas flow measured by a humidity sensor, and indicating degradation of the humidity sensor if a humidity of a second gas flow measured by the humidity sensor is different than an expected humidity. In this way, degradation of the humidity sensor may be indicated if the humidity of the second gas flow measured by the humidity sensor is different than expected. | 08-28-2014 |
20140244135 | DISTINGUISHING BETWEEN EGR VALVE AND OXYGEN SENSOR DEGRADATION - A diagnostic method for an engine having a valve for controlling dilution of intake air. The method comprises, during engine fueling, indicating a degradation of the valve when the valve is commanded closed but sensor output corresponds to an oxygen level below that of air. The method further comprises, absent engine fueling, indicating degradation of the sensor when the valve is commanded closed but the sensor output corresponds to an oxygen level below that of air. | 08-28-2014 |
20140298880 | HUMIDITY SENSOR DIAGNOSTIC METHOD USING CONDENSATION CLEARING HEATER - A diagnostic method for a capacitive humidity sensor comprising a heater, and a capacitance-sensing element that individually indentifies heater, temperature-sensing element, or capacitance-sensing element degradation. By this method, individual elements of the sensor may be replaced or compensated for to allow for further operation. | 10-09-2014 |
20140303873 | POSITION DETECTION FOR LOBE SWITCHING CAMSHAFT SYSTEM - Systems and methods for determining an active cam profile from a plurality of cam profiles is disclosed. The systems and methods may be used to determine how to operate an engine torque actuator or provide an indication of cam profile switching degradation. | 10-09-2014 |
20140316672 | HUMIDITY SENSOR AND ENGINE SYSTEM - Methods and systems are provided for an engine coupled temperature-based humidity sensor. Degradation of the humidity sensor may be determined while flowing gasses into an engine intake air downstream of a humidity sensor and upstream of a compressor, indicating humidity sensor degradation when relative humidity readings change by less than a threshold while temperature at the sensor changes greater than a second threshold. | 10-23-2014 |
20140316676 | HUMIDITY SENSOR AND ENGINE SYSTEM - Methods and systems are provided for an engine coupled capacitance-based humidity sensor. Degradation of the humidity sensor may be determined based on humidity readings while flowing gasses into an engine intake air downstream of the humidity sensor and upstream of a compressor change by less than a first threshold while pressure at the sensor changes greater then a second threshold. The variation in pressure can be changed by adjusting a throttle upstream and downstream of the compressor based on whether the humidity sensor is degraded or functional. | 10-23-2014 |
20140336899 | INTEGRATED FUEL CATALYST MONITOR - A method is provided for monitoring an emission device coupled to an engine. In one example approach, the method comprises: following a deceleration fuel shut-off duration, indicating degradation of the emission device based on an amount of rich products required to cause a sensor to become richer than a threshold. The amount of rich products required may be correlated to an amount of oxygen stored in the emission device. | 11-13-2014 |
20140345584 | EXHAUST GAS SENSOR CONTROLS ADAPTATION FOR ASYMMETRIC DEGRADATION RESPONSES - Methods and systems are provided for converting an asymmetric degradation response of an exhaust gas sensor to a more symmetric degradation response. In one example, a method includes adjusting fuel injection responsive to a modified exhaust oxygen feedback signal from an exhaust gas sensor, the modified exhaust oxygen feedback signal modified by transforming an asymmetric response of the exhaust gas sensor to a more symmetric response. Further, the method may include adjusting one or more parameters of an anticipatory controller of the exhaust gas sensor based on the modified symmetric response. | 11-27-2014 |
20140360477 | SYSTEM AND METHOD FOR DETERMINING VALVE OPERATION - Systems and methods for determining operation of a cylinder deactivating/reactivating device are disclosed. In one example, degradation of the cylinder deactivating/reactivating device is based on intake manifold oxygen concentration. | 12-11-2014 |
20150027107 | NOX CONTROL DURING ENGINE IDLE-STOP OPERATIONS - Methods and systems are provided for improving engine exhaust emissions while enabling exhaust catalyst regeneration following an engine lean event. Prior to a VDE event, or prior to an engine idle-stop, ammonia is produced and stored on an exhaust underbody SCR catalyst. Then, during the engine restart after the VDE mode or the idle-stop, the stored ammonia is used to treat exhaust NOx species while an upstream exhaust underbody three-way catalyst is regenerated. | 01-29-2015 |
20150051812 | TWO-STAGE CATALYST REGENERATION - A system and method are described for reducing NOx emissions following deceleration fuel shut off (DFSO). The method comprises: cutting off fuel to the engine during a deceleration event; open loop operating the engine air/fuel ratio rich of stoichiometry for a predetermined time after the deceleration event; feedback controlling the air/fuel ratio on average near a value rich of stoichiometry for a preselected time after said predetermined time; and feedback controlling the air/fuel ratio returning to stoichiometry after the preselected time. | 02-19-2015 |
20150066334 | METHOD AND SYSTEM FOR HUMIDITY SENSOR DIAGNOSTICS - Methods and systems are provided for an engine including a humidity sensor. Degradation of the humidity sensor may be determined based on a change in intake air relative humidity as compared to a change in intake air temperature or pressure, under selected conditions. An amount of exhaust gas recirculated to an engine intake is adjusted differently based on whether the humidity sensor is degraded or functional. | 03-05-2015 |