Abstract: An evaporative purge system 10 of an internal combustion engine 14 powered motor vehicle is monitored using one or more relatively long time tests in the cruise operating mode of the motor vehicle to screen for emission of vapors which, allegedly, contributes to smog. If emission is detected in the cruise operating mode, a command is generated and stored in memory to subsequently monitor the system in the idle operating mode. The evaporative purge system is subsequently monitored using a relatively short time test in the idle operating mode of the motor vehicle to confirm vapor emission.

Abstract: An engine control system of an internal combustion engine coupled to a NOx trap uses a measured air-fuel ratio downstream of the NOx trap to control engine air-fuel ratio. The measured air-fuel is only used for feedback when it indicates a value away from stoichiometry. Thus, NOx and oxygen storage effects that cause inlet air-fuel ratio to be different from exit air-fuel ratio do not cause degraded feedback air-fuel ratio control.

Abstract: A method for monitoring a powertrain of a vehicle is described where powertrain output is estimated based on fuel when the powertrain operates lean of stoichiometry and powertrain output is estimated based on air when the powertrain operates rich of stoichiometry. Powetrain output is then compared with a preselected output and a reaction is initiated in response to the comparison.

Abstract: A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses a NOx sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Nitrogen oxide conversion efficiency of the catalyst is controlled by controlling the reductant injection based on after catalyst NOx sensor reading and engine out nitrogen oxide concentration.

Abstract: A method for monitoring an electronically controlled drive unit of a vehicle uses actual vehicle acceleration and a preselected vehicle acceleration. Actual acceleration is determined from any of an acceleration sensor or vehicle speed sensors. When actual acceleration is greater than the preselected acceleration, a reaction is initiated to reduce vehicle acceleration.

Abstract: A method for controlling cycling of an air conditioning compressor coupled to an internal combustion engine interrupts normal cycling based on operation conditions. In addition, normal engaged and disengaged cycling durations are adaptively estimated in real-time. The method of the present invention achieves improved fuel economy and improved drive feel. As an example, improved fuel economy is achieved by engaging the compressor during braking or when the engine is being driven by the vehicle. As another example, improved drive feel is achieved by engaging the compressor during transient conditions when drive feel is unaffected.

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: A method for monitoring an electronically controlled drive unit of a vehicle uses actual vehicle acceleration and a preselected vehicle acceleration. Actual acceleration is determined from any of an acceleration sensor or vehicle speed sensors. When actual acceleration is greater than the preselected acceleration, a reaction is initiated to reduce vehicle acceleration. A method for controlling vehicle acceleration is also disclosed where desired acceleration is determine from either the operator command or a cruise control system.

Abstract: A method for controlling mode transitions, such as from stratified to homogeneous mode, in a direct injection engine adjusts an intake manifold outlet control device, such as a cam timing, to rapidly control cylinder fresh charge despite manifold dynamics. In addition, a coordinated change between an intake manifold inlet control device, for example a throttle, and the outlet control device is used to achieve the rapid cylinder fresh charge control. In this way, engine torque disturbances during the mode transition are eliminated, even when cylinder air/fuel ratio is changed from one cylinder event to the next.

Abstract: A system and method for controlling an engine include determining a desired engine brake torque and modifying the desired engine brake torque based on current engine operating conditions to determine a requested engine brake torque prior to determination of control parameters, including at least one of an airflow and a fuel quantity, to effect the requested engine brake torque. Preferably, the desired engine brake torque is modified by combining the desired engine brake torque with an idle speed torque to generate a first intermediate torque, comparing the first intermediate torque to an actual engine brake torque to generate a second intermediate torque, generating a feedback correction torque based on the second intermediate torque, and combining the first intermediate torque, the feedback correction torque, and a third intermediate torque to determine the requested engine brake torque, where the third intermediate torque represents accessory load or a frictional torque loss which varies with temperature.

Abstract: A system and method for transient torque control of a direct injection spark ignition engine include controlling airflow and fuel flow rather than ignition timing so that spark timing may be set for best fuel economy. The system and method are particularly suited for variable cam timing or variable valve timing DISI engines where valve timing enables a sufficiently fast engine torque response to achieve transient control. The present invention may be used for torque-based speed control strategies, such as idle speed control or cruise control. The invention includes determining a maximum available airflow to determine whether a desired torque and air/fuel ratio can be achieved using airflow. Otherwise, the invention uses fuel flow control based on the maximum available air flow to provide the desired engine output torque and air/fuel ratio.

Abstract: An electronic engine controller controls the catalytic converter temperature by generating a desired rich air/fuel ratio that will maintain the catalytic converter at a predetermined temperature. The actual air/fuel ratio is ramped to the desired air/fuel ratio at a first rate when the catalytic converter temperature is greater than a first predetermined temperature. The actual air/fuel ratio is ramped to the desired air/fuel ratio at a second rate when the catalytic converter temperature is greater than a second predetermined temperature but less than the first predetermined temperature.

Abstract: An engine control system controls engine torque to transition through the transmission lash zone. The transmission lash zone is determined using speed ratio across the torque converter. When near the transmission lash zone, engine torque is adjusted at a predetermined rate until the system passes through the transmission lash zone. By limiting the change of torque in this way, driveability is improved and it is possible to quickly and reliably provide negative engine torque for braking.

Abstract: A powertrain control method for an internal combustion engine having a throttle responsive to a throttle position command. The method comprises the steps of determining the engine speed, determining the actual throttle position, and generating a desired throttle position value. In one aspect of the invention, the desired throttle position value is generated as a function of the actual throttle position and engine speed. In particular, the throttle position divided by the engine speed can be resolved to a single constant. As such, a simplified powertrain control monitor can be obtained by comparing the throttle position divided by engine speed to a predetermined constant. If the throttle position is greater than the desired throttle position value, the commanded throttle position is limited to the desired value.

Abstract: A fuel vapor purging method controls fuel vapor purging during stratified operation. Several factors influence vapor purge control, including fuel vapor concentration in the cylinder and temperature of the emission control device. The fuel vapor passes through the cylinder unburned by maintaining the concentration within allowable limits. The unburned fuel vapor reacts exothermically in the emission control device thereby generating heat. To guarantee that the fuel vapor reacts in the first emission control device, the fuel vapor purge is restricted to a certain temperature range. To guarantee that the fuel vapor does not burn in the cylinder, the concentration is kept to a restricted value.

Abstract: A method is presented for controlling powertrain torque by minimizing the error between the actual powertrain torque (as read by the torque sensor) and the desired powertrain torque (as requested by the vehicle driver). Since torque sensors are known to drift under certain conditions, such as high ambient temperature, the output of the torque sensor is adjusted by an offset value. This offset value is determined by reading the torque sensor output when the speed ratio (engine speed/turbine speed) is substantially unity, and the net torque at the torque converter is substantially zero. This adjusted output is then filtered to avoid abrupt fluctuations in the powertrain torque, and used to improve powertrain control so that better drive feel and increased fuel economy can be achieved.

Abstract: A method for controlling reductant added to an exhaust of an engine having a lean NOx catalyst and a particulate filter adjusts a reductant amount during particulate filter regeneration. The method adjusts the reductant amount to account for reducing agents released from the particulate filter that are experienced by the lean NOx catalyst. In addition, management of particulate filter regeneration is based on both an estimated amount of stored particles and conditions of the lean NOx catalyst. In this way, operation of both the particulate filter and the lean NOx catalyst can be optimized. Also, termination of particulate filter regeneration is determined based on operating conditions.

Abstract: A vacuum actuated valve uses a specially designed spring having a spring rate as a function of valve position. The spring rate function is determined using physical relationships between flow, pressure, and valve s position. The result is that the relationship between the control input to the valve (either a vacuum signal, or an electrical signal to a vacuum source) and the flow through the valve are linearly related through the entire operating region of the valve.

Abstract: A method for controlling an engine having both an electronically controlled inlet device, such as an electronic throttle unite, and an electronically controlled outlet device, such as a variable cam timing system is disclosed. The method of the present invention achieves cylinder air charge control that is faster than possible by using an inlet device alone. In other words, the method of the present invention controls cylinder air charge faster than manifold dynamics by coordination of the inlet and outlet device. This improved control is used to improve various engine control functions.

Abstract: A method for controlling mode transitions, such as from stratified to homogeneous mode, in a direct injection engine adjusts a number of cylinders carrying out combustion to prevent engine torque disturbances. Cylinder activation is used when changes in cylinder air/fuel ratio cannot be compensated using ignition timing adjustments. In addition, the number of cylinders to activate is also determined and measures are taken if the number of cylinders determined are not available to be activated.