Abstract: A vehicle powertrain has an engine coupled to an electronically-controlled automatic transmission. A method for controlling the vehicle powertrain during a transmission shift from a neutral gear to a drive gear detects a change in a signal indicative of a desired transmission gear change from a neutral gear to a drive gear. An engine idle speed is reduced by a predetermined RPM in response to the change in the signal. The transmission is shifted from the neutral gear into the drive gear upon the engine idle speed being reduced by the predetermined RPM.

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 for controlling the temperature of a catalyst in a catalytic converter. The method includes the steps of calculating a stabilized catalyst temperature limit, determining a stabilized catalyst temperature without enrichment, comparing the stabilized catalyst temperature limit with the stabilized catalyst temperature without enrichment and enriching a fuel/air ratio to maintain a stabilized catalyst temperature at the stabilized catalyst temperature limit if the stabilized catalyst temperature without enrichment is greater than the stabilized catalyst temperature limit. A vehicle having a controller for controlling the enrichment of an air/fuel ratio to control the temperature of a catalyst in a catalytic converter is also provided.

Abstract: An ambient temperature learning algorithm provides a series of ambient temperature estimates which are calculated as a function of the induction air temperature as measured by an induction temperature sensor and this series of estimates is then filtered to provide an accurate reading of the actual ambient temperature. To increase the accuracy of the ambient temperature following an engine-off soak period, the initial estimate of the ambient can be made based upon several criteria. If the engine has not run for several hours, the induction system measurement from which the estimates are made is a good starting value. How long the engine has been off can be determined by a soak timer in the vehicle or by comparing the engine coolant temperature with the induction system temperature. If the coolant and induction system temperatures are very close, the soak period can be assumed long enough for the induction temperature to be a good starting point for the learned ambient temperature.

Abstract: A method for monitoring the efficiency of a catalytic converter in a motor vehicle includes the steps of determining if at least one predetermined condition is met for monitoring the efficiency of the catalytic converter. The method includes biasing a fuel feedback multiplier of an internal combustion engine of the motor vehicle to run rich or lean if the at least one predetermined condition is met. The method includes counting a number of switches across a predetermined switch point from an upstream oxygen sensor and a downstream oxygen sensor. The method includes calculating a switching frequency ratio based on the count of the switches from the upstream oxygen sensor and downstream oxygen sensor and using the switching frequency ratio to establish the efficiency level of the catalytic converter.

Abstract: A method of monitoring efficiency of a catalytic converter in a motor vehicle includes the steps of determining if at least one predetermined condition is met for monitoring the efficiency of the catalytic converter and combining a square wave multiplier signal with a feedback multiplier signal if the at least one predetermined condition is met. The method includes counting a number of square wave edges of the combined signal for an upstream oxygen sensor positioned upstream of the catalytic converter and counting a number of switches of a signal across a predetermined switch point from a downstream oxygen sensor positioned downstream of the catalytic converter. The method also includes the steps of calculating a switching frequency ratio based on the count of square wave edges and oxygen sensor switches and using the switching frequency ratio to establish the efficiency level of the catalytic converter.

Abstract: An after-burner heated catalyst control system and associated control circuit for controlling operation of an after-burner heated catalyst. The control circuit has an air pump motor, a spark plug, and a fuel injector, while the catalyst is disposed within an exhaust passageway of the engine. The control circuit further includes an apparatus for controlling operation of and pulse wave modulating the air pump motor, one spark plug, and fuel injector. An RS232 interface is provided for transmitting and receiving data from and to the control circuit. In addition a method is provided for controlling a temperature of an after-burner heated catalyst and adjusting adaptively the pulse wave modulation of the air pump motor, spark plug, and fuel injector.