Abstract: A method for controlling a vehicle driveline uses sensors to estimate a need for powering secondary wheels for each of a plurality of conditions. The estimates are scaled and the scaled estimates summed. Only primary wheels are powered when the summed estimates are less than a reference value. Both the primary and secondary wheels are powered when the summed estimates exceed the reference value.

Abstract: A method for controlling a vehicle driveline uses sensors to estimate a need for powering secondary wheels for each of a plurality of conditions. The estimates are scaled and the scaled estimates summed. Only primary wheels are powered when the summed estimates are less than a reference value. Both the primary and secondary wheels are powered when the summed estimates exceed the reference value.

Abstract: A vehicle driveline includes a power source, a transmission connected to the power source and including an output driveably connected to primary road wheels, a driveshaft, a synchronizer that opens and closes a drive connection between the output and the driveshaft, and a clutch that alternately opens and closes a drive connection between the driveshaft and secondary road wheels. A control executes synchronization and connection strategies using one of singular, overlapping and sequential activation of the driveline components that produce all-wheel-drive on-demand.

Abstract: A method for controlling a vehicle driveline includes using current conditions to estimate wheel slip probability and vehicle dynamics handling support requirements, producing two-wheel drive operation, if said slip probability and handling support requirement is low and a condition for forced driveline connection is absent, and producing four-wheel drive operation, if said slip probability and/or handling support requirement is high and a condition for forced driveline disconnection is absent.

Abstract: A vehicle driveline includes a power source, a transmission connected to the power source and including an output driveably connected to primary road wheels, a driveshaft, a synchronizer that opens and closes a drive connection between the output and the driveshaft, and a clutch that alternately opens and closes a drive connection between the driveshaft and secondary road wheels. A control executes synchronization and connection strategies using one of singular, overlapping and sequential activation of the driveline components that produce all-wheel-drive on-demand.

Abstract: A method and system for controlling gear ratio changes of a transmission operating in a powertrain with an internal combustion engine controlled by an engine throttle and having a device, such as traction assist system, that alters engine torque from that corresponding to the position of the throttle. The control substitutes a synthetic throttle position for actual throttle position during a traction assist event. Gearshifts occur with reference to a schedule relating the desired gear, vehicle speed, and synthetic throttle position.

Abstract: An electronic driveline controller and traction control method for an engine driven vehicle wherein the tractive effort of the driving wheels is controlled to avoid excess slip of the traction wheels relative to the vehicle road surface, the traction control being achieved by total powertrain torque management whereby the torque delivered to the driving wheels is a control parameter that depends upon the magnitude of sensed operating variables for the vehicle driveline.

Abstract: A method for reducing the engine torque being produced by an internal combustion engine to a desired engine torque through coordinated control of spark retard, cylinder cut-out and air/fuel scheduling. The method is for use with a vehicle including a multi-cylinder internal combustion engine capable of generating torque, each cylinder having an associated fuel injector for providing fuel to the cylinder and an associated spark timing control for providing a spark for combustion of the fuel with fresh air during engine operation. The method includes identifying the desired engine torque to which the engine torque being produced is to be reduced, and determining a first torque reduction to be achieved by defueling at least one of the engine cylinders.

Abstract: A system for controlling the flow of air entering the intake manifold of a multicylinder variable displacement internal combustion engine installed in a vehicle having a driver-operable accelerator control includes an accelerator control position sensor for determining the operating position of the accelerator control and for generating an accelerator control position signal indicating such position, as well as an engine speed sensor for determining the speed of the engine and for generating an engine speed signal indicating such speed. The present system further includes an engine cylinder operator for deactivating and reactivating at least some of the cylinders and an electronically controlled throttle valve positioned in the intake manifold of the engine so as to control the amount of air entering the engine's cylinders.

Abstract: Apparatus and method are disclosed for monitoring catalytic converter efficiency in treating exhaust gas, for example from an internal combustion engine of a motor vehicle. In a dual closed loop fuel control system having switch-type exhaust gas oxygen (EGO) sensors located upstream and downstream of the catalytic converter, the number of times the downstream EGO sensor switches from rich to lean and/or visa versa is compared to the number of times the upstream EGO sensor switches during normal system operation over the course of a test period. A catalytic converter efficiency value is determined by calculating the ratio of the switching frequencies. The impact of the speed and load dependence of the downstream EGO sensor switching frequency can be reduced by a normalizing effect of the frequency ratio calculation. The efficiency value is compared to a stored value predetermined to correspond to a minimum acceptable efficiency of the catalytic converter.

Abstract: Apparatus and method are disclosed for monitoring catalytic converter efficiency in treating exhaust gas from an internal combustion engine having fuel control means for controlling the air to fuel ratio at which fuel is supplied to the engine in response to a fuel flow control signal. During a normal operation mode, the control signal means generates the fuel flow control signal based at least in part on output signals from first and second EGO sensors exposed to the exhaust gas upstream and downstream, respectively, of the catalytic converter. The normal operation mode is periodically interrupted by a test operation mode, preferably initiated during substantially steady state operation of the engine, during which the engine is controlled in response to the output signal from the first EGO sensor without the signal from the second EGO sensor.

Abstract: An exhaust gas oxygen sensor downstream of a catalytic converter is used to control a closed loop air/fuel ratio control system. A measured limit cycle frequency at various engine speed/load conditions is compared to stored benchmark limit cycle frequencies as functions of engine speed/load conditions. If the measured frequency is higher, the catalytic converter is considered to be degraded.