Abstract: In a motor vehicle having an engine with an exhaust catalyst and an oxygen sensor upstream of the catalyst and an oxygen sensor downstream of the catalyst, a method for detecting whether the catalyst has aged. Over a test block period of time, the method periodically obtains upstream data points from an oxygen sensor located upstream of the catalyst and from and oxygen sensor located downstream of the catalyst. Absolute differences are calculated between consecutive pairs of the upstream data points and the downstream data points. A ratio between the sums of absolute differences is then calculated, and the ratio is used to determine whether the catalyst has aged.

Abstract: A non-intrusive method and arrangement for detecting the aging of an oxygen sensor, without increasing tailpipe emissions, is provided. The method detects an aging oxygen sensor, located between a motor vehicle engine and a catalytic converter, by sampling a series of oxygen level signals taken over a calibratable time block only when at least one engine operating condition satisfies a predetermined criterion whereunder the method will not intrude upon the engine controller's ability to minimize undesirable exhaust emissions. After a series of signal processing, the samplings are then compared to calibratable thresholds in order to determine the aging degree of the oxygen sensor.

Abstract: A non-intrusive method and arrangement for detecting the aging of an oxygen sensor, without increasing tailpipe emissions, is provided. The method detects an aging oxygen sensor, located between a motor vehicle engine and a catalytic converter, by sampling a series of oxygen level signals taken over a calibratable time block only when at least one engine operating condition. satisfies a predetermined criterion whereunder the method will not intrude upon the engine controller's ability to minimize undesirable exhaust emissions. After a series of signal processing, the samplings are then compared to calibratable thresholds in order to determine the aging degree of the oxygen sensor.

Abstract: In a motor vehicle having an engine with an exhaust catalyst and an oxygen sensor upstream of the catalyst and an oxygen sensor downstream of the catalyst, a method for detecting whether the catalyst has aged. Over a test block period of time, the method periodically obtains upstream data points from an oxygen sensor located upstream of the catalyst and from and oxygen sensor located downstream of the catalyst. Absolute differences are calculated between consecutive pairs of the upstream data points and the downstream data points. A ratio between the sums of absolute differences is then calculated, and the ratio is used to determine whether the catalyst has aged.

Abstract: A method for calculating the temperature of a catalyst in a catalytic converter. The method includes the steps of determining a first catalyst temperature; determining a stabilized catalyst temperature; and using the first catalyst temperature, the stabilized catalyst temperature and an update fraction to calculate an updated catalyst temperature.

Abstract: A method of controlling a vapor storage canister for a purge control system of an internal combustion engine is provided. The method includes the steps of determining if predetermined conditions are right for controlling a vapor storage canister and maintaining normal fuel feedback operation if the predetermined conditions are not right for controlling the vapor storage canister. The method also includes the steps of determining if the vapor storage canister is loaded if the predetermined conditions are right for controlling the vapor storage canister, maintaining normal fuel feedback operation if the vapor storage canister is not loaded and modifying a duty cycle of a purge solenoid to maximize purge if the vapor storage canister is loaded. The method further includes the steps of updating a loaded canister total purge multiplier and using the total purge multiplier to vary the amount of fuel being delivered to the internal combustion engine.