Abstract: A method and apparatus for aging a catalyst includes selecting an initial catalyst conditioning parameter, such as time and temperature and selecting a kinetic parameter, based on the selected time and temperature parameter, for the catalysis of CO and HC oxidation by the catalyst. A prediction of the vehicle tailpipe emission level, based on the selected kinetic parameter is made. The predicted level is then compared to a target level to determine whether the particular parameters chosen are appropriate to age the catalyst. The catalyst is then aged based on the desired selected parameters.

Abstract: A system and method for monitoring efficiency of a catalytic converter count switches of at least one upstream sensor interposed the engine and the converter and count switches of a downstream sensor, interposed the converter and atmosphere, during a definite time period after a switch of the at least one upstream sensor to account for propagation delay of exhaust gases traveling between the at least one upstream and downstream sensor. Upstream sensor switches may optionally be counted only if predetermined entry conditions are satisfied while downstream switches occurring during respective definite time periods after an upstream switch are counted without regard to the entry conditions. A switch ratio based on the number of switches of the at least one upstream sensor and switches of the downstream sensor is used to monitor conversion efficiency of the catalyst.

Abstract: A system and method for monitoring catalytic converter efficiency monitor the switch ratio of upstream and downstream exhaust gas oxygen sensors based on an acceptable temperature range of the catalytic converter mid-bed for each of a number of mass air flow ranges. The system and method also use vehicle speed and EGR to assure that the monitor samples data during repeatable, robust load-speed-temperature conditions. Switch data is stored in keep-alive memory to increase the confidence of the efficiency determination due to a larger data collection phase. A filter having a cycle based constant is used to filter a current switch ratio before incorporating it into an average switch ratio.

Abstract: A method and system for monitoring the efficiency of a catalytic converter include determining a ratio of signal arc lengths from an upstream exhaust gas sensor and a downstream exhaust gas sensor which generate signals indicative of oxygen content in the exhaust upstream and downstream, respectively, relative to the converter. A controller processes the signals to determine the ratio of the arc length of the rear or downstream sensor signal to the arc length of the front or upstream sensor signal over a test period. The arc length is calculated by summing over the test period a series of incremental arc lengths for each incremental time interval in the test period. An incremental signal length may be calculated using the square root of the sum of the square of the change in value of a signal during an incremental time interval and the square of the duration of the incremental time interval.

Abstract: A system and method for monitoring emissions by monitoring performance of a catalytic converter using a predetermined indicated threshold value include determining a current value for the indicator based on signals generated by at least one exhaust gas sensor, modifying a historical indicator value based on the current value, and adjusting the predetermined indicator threshold based on the historical indicator value. The predetermined indicator threshold is adjusted provided various adapt criteria are satisfied. The historical indicator value is compared to the threshold to determine whether to generate a malfunction indicator signal. In one embodiment, emissions are indicated using a switch ratio based on the number of switches or transitions for upstream and downstream exhaust gas oxygen sensors.

Abstract: An on-board diagnostic test for an exhaust gas oxygen sensor includes sensing the output of the oxygen sensor and summing the output over a specified period to determine the length of the trace of the sensor voltage versus time. Such length over a given time period indicates the activity of the sensor. This data is compared to a threshold to determine if the exhaust gas oxygen sensor meets certain performance requirements.