Abstract: A system and method for controlling an internal combustion engine using a controller to implement at least two control modes having corresponding first and second mode controllers with disparate control parameters include comparing output of the first and second mode controllers to generate an error, generating a correction value based on the error, and providing the correction value to one of the mode controllers to provide a smooth transition of control between the mode controllers. In one embodiment, the first controller is a torque controller which determines a desired air flow to achieve a desired torque and the second mode controller is an idle speed controller which determines a desired air flow to maintain a desired engine speed. The invention is advantageous in that it provides for smooth transitions between control modes, such as between idle mode and a normal driving mode, by harmonizing the outputs of the controllers.

Abstract: A method and apparatus for inferring and controlling the temperature of a NO.sub.x trap located downstream from a three-way catalyst that employs a temperature sensor to correct a temperature estimation model under relatively steady-state conditions to provide a more accurate estimate of NO.sub.x trap temperature and three-way catalyst temperature. In a second embodiment, the three-way catalyst also includes a temperature sensor for improving the instantaneous catalyst temperature estimation.

Abstract: A system for calibrating production throttle bodies in which a throttle body (18) is mounted in a fixture (16) and light is transmitted by a light source (12) through the throttle body main bore (20) onto a translucent screen (22). A camera (14) senses the light regions (34) and transmits the information to a controller (26), which calculates the angular position of the throttle valve (32).