Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses an ammonia sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Ammonia concentration detected downstream of the catalyst is controlled to a desired value, with the desired value based on catalyst temperature and the open loop injection quantity.

Abstract: Method and apparatus for monitoring a catalytic converter (32) during engine (catalyst) warm-up by first and second heated exhaust gas oxygen sensors (60, 70) located upstream and downstream, respectively, of the catalytic converter. A microprocessor determines a change of signal output of the downstream sensor relative to signal output of the upstream sensor during engine (catalyst) warm-up initiated by engine cold starting during the catalyst warm-up period. A catalyst light-off temperature is determined by the microprocessor when the change occurs. The catalyst light-off temperature thus determined is compared to a stored reference catalyst light-off temperature that is indicative of a properly functioning (e.g. fresh) catalyst to assess the extent or degree of degradation of the catalyst.

Abstract: A method for controlling a powertrain of a vehicle adjusts a minimum allowed airflow based on operating conditions. Specifically, when conditions of engine speed and/or vehicle speed area away from idle conditions, no increasing of the minimum allowed airflow is carried out. However, when conditions of engine speed and/or vehicle speed area approaching idle conditions, the minimum allowed airflow is increased to the required airflow for those idle conditions.

Abstract: A method for approximating compressible flow is described that is applicable across any pressure range of interest uses upstream and downstream pressure. The approximation minimizes variance with respect to a true flow equation. A flow control system is given using the new method that achieves accurate control with minimum complexities. The control system is application to various systems, including internal combustion engine airflow control, internal combustion engine exhaust gas recirculation control, internal combustion engine alternative fuel flow control, and many other compressible flow control problems.

Abstract: A vehicle control system is described for controlling a torque converter coupled to an engine. The controller engages the torque converter before negative powertrain output becomes less than a predetermined value. Such an approach allows for torque converter locking in the negative powertrain output region. Such an approach is especially suited to vehicles having certain torque converters, which are difficult to lock at large negative torque values.

Abstract: A method and apparatus for operating a lean-burn internal combustion engine in cooperation with an exhaust gas purification system having a three-way catalyst and a NOx trap located downstream of the three-way catalyst includes a controller which calculates current levels of tailpipe NOx during lean engine operating conditions based upon the difference between a determined instantaneous feedgas NOx concentration and a determined instantaneous trap efficiency. The controller discontinues lean engine operation when the tailpipe NOx, expressed in terms of either grams-per-mile or grams-per-hour, exceeds a predetermined threshold level, either instantaneously or as averaged over the course of a trap purge-fill cycle.

Abstract: The invention relates to a new method and system for optimizing the efficiency of an automotive catalytic converter. The claimed invention comprises adjusting an air/fuel ratio in the cylinders of an internal combustion engine to maintain a desired level of oxidants in the catalytic converter. At various times, the actual amount of oxidants stored in the catalytic converter is determined. The actual oxidant amount is compared to a target amount of oxidants to be stored in the catalytic converter. The air/fuel ratio in the cylinders is adjusted based on the magnitude of the difference between the actual oxidant amount and the target oxidant amount to prevent NOx and hydrocarbon breakthrough.

Abstract: A direct injection engine is coupled to a vacuum brake booster wherein vacuum created from engine pumping is used to supplement driver braking force. The brake booster is coupled through a check valve to the engine intake manifold. A method for estimating pressure in the brake booster uses various engine and vehicle operating conditions. A method for estimating operating parameters uses measured brake booster pressure. Further, a method for diagnosing degradation, or monitoring, a brake booster pressure sensor is based on engine or vehicle operating conditions. In addition, a method for diagnosing degradation in other vehicle and engine sensors uses measured brake booster pressure.

Abstract: A method for purging a catalyst containing oxidants operates the engine at different air-fuel ratios during different intervals. The intervals are adaptively adjusted based on a model that predicts an amount of fuel needed to perform the purging. The intervals are also responsive to an exhaust gas sensor located downstream of the catalyst.

Abstract: An engine control system for managing lean NOx trap decontamination uses associated fuel economy impacts to determine when decontamination is enabled. In particular, a maximum achievable benefit provided by lean operation with a decontaminated NOx trap, a present fuel economy benefit being provided by lean operation, and a fuel economy penalty for performing decontamination are used. When a resulting benefit is greater than a penalty, decontamination is enabled.

Abstract: An electronic throttle control system is described where a throttle position sensor has multiple slopes depending on the operating region. At low throttle positions, a greater slope, and thus a greater sensitivity is provided, thereby increasing control resolution. At greater throttle positions, a lower slope, and thus lower sensitivity is provided. In this way, an output signal that varies across the entire operating region of the throttle is provided for monitoring and control, while improved performance at low throttle angles can be simultaneously achieved. A method of making the sensor is also described.

Abstract: A method and apparatus for controlling the operation of a “lean-burn” internal combustion engine in cooperation with an exhaust gas purification system having an emissions control device capable of alternatively storing and releasing NOx when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, determines a performance impact, such as a fuel-economy benefit, of operating the engine at a selected lean operating condition, with due consideration of the periodic rich operating condition necessary to release stored NOx from the device. The method and apparatus further determine a measure representative of the instantaneous NOx-storing efficiency of the device. The method and apparatus enable the selected lean operating condition as long as the determined performance impact and the determined device efficiency are each above respective predetermined minimum levels.

Abstract: A method and system for determining whether a desired amount of hydrocarbon is actually injected into an engine exhaust to react with NOx in such engine exhaust. The reaction is facilitated with a catalyst downstream of the hydrocarbon injection. The method and system measure a first temperature difference across the catalyst during the reaction. The first temperature difference is compared with an expected temperature difference across the catalyst during the reaction. The difference in exotherm is used to adjust the injected HC quantity, and diagnose injector failures.

Abstract: An engine control system for managing lean operation of an internal combustion engine coupled to a lean NOx trap uses an indication of vehicle activity. A target amount of tailpipe emission per distance is adjusted based on the vehicle activity indication. Then, engine air-fuel ratio is controlled based on the adjusted target amount of tailpipe emission per distance. Also, the indication of vehicle activity is used to enable decontamination cycles of the lean NOx trap.

Abstract: An engine control system for managing lean NOx trap decontamination uses associated fuel economy impacts to determine when decontamination is enabled. In particular, a maximum achievable benefit provided by lean operation with a decontaminated NOx trap, a present fuel economy benefit being provided by lean operation, and a fuel economy penalty for performing decontamination are used. When a resulting benefit is greater than a penalty, decontamination is enabled.

Abstract: An engine control system for managing lean operation of an internal combustion engine coupled to a lean NOx trap uses an indication of vehicle activity. A target amount of tailpipe emission per distance is adjusted based on the vehicle activity indication. Then, engine air-fuel ratio is controlled based on the adjusted target amount of tailpipe emission per distance. Also, the indication of vehicle activity is used to enable decontamination cycles of the lean NOx trap.

Abstract: The invention relates to a new method and system for optimizing the efficiency of an automotive catalytic converter by adjusting the engine air/fuel ratio based on estimates of the actual amount of oxidants stored in the catalyst. To dQ so, the invented system estimates an amount of oxidants stored in the catalyst. The amount of oxidants stored is estimated by determining an amount of oxidants that are available for storage by the catalyst or that are needed to oxidize hydrocarbons being produced by the engine. The estimate of the amount of oxidants that are available for storage by the catalyst or that are needed to oxidize hydrocarbons is adjusted based on a feedback parameter. Further, the desired amount of oxidants stored in the device is adjusted based on a prediction of future operating conditions.

Abstract: A method for controlling an engine coupled to a transmission is described. The method is especially suited for a transmission having at least one gear in which an over-running clutch is present. The invention describes a method for adjusting an engine operating parameter to maintain transmission input speed at or below a synchronous transmission input speed when the transmission is in the gear with the over-running clutch. The synchronous transmission input speed is based on transmission state and transmission output speed. Alternatively, vehicle speed can be used in place of transmission output speed.

Abstract: A fuel control method uses a MAP sensor output that is encoded to render fueling computations insensitive to microprocessor clock accuracy. The signal output of the MAP sensor is encoded as a pulse width modulated signal, the cylinder air mass is calculated as a function of the encoded MAP signal and the engine is fueled according to the calculated cylinder air mass. By using the same time scale to decode the pulse width of the MAP PWM signal as is used to time injector duration, the time scale becomes irrelevant to the actual fuel/air ratio attained.

Abstract: An electronic throttle control system is described where a throttle position sensor has multiple slopes depending on the operating region. At low throttle positions, a greater slope, and thus a greater sensitivity is provided, thereby increasing control resolution. At greater throttle positions, a lower slope, and thus lower sensitivity is provided. In this way, an output signal that varies across the entire operating region of the throttle is provided for monitoring and control, while improved performance at low throttle angles can be simultaneously achieved. A method of making the sensor is also described.