Abstract: The present invention provides a system and method for starting a vehicle in a cold temperature environment and minimizing the time spent by the vehicle within a resonance frequency zone during operation. The present invention includes a method of starting a vehicle engine comprising adjusting the speed of the engine during an engine start mode in accordance with a fixed value threshold. The method also includes determining whether the engine speed has reached the fixed value threshold or whether a time-based threshold has been reached. The method further includes transitioning out of the engine start mode into a normal operating mode when either the fixed value threshold or the time-based threshold has been reached.

Abstract: A control method is disclosed for maintaining a calibrated minimum load for an engine in a vehicle powertrain with an engine. The possibility of engine misfire due to low engine loads is reduced. Further, undesired high temperature of an engine exhaust gas catalytic converter due to prolonged operation of the powertrain at low engine loads is avoided.

Abstract: A system and method for controlling a vehicle powertrain having an internal combustion engine include determining a difference between a desired engine torque and a current engine torque, adjusting the difference based on a stored torque offset corresponding to a current engine speed, and controlling the engine to produce a torque corresponding to the adjusted torque difference. The stored torque offset is adjusted when the engine is operating in a predetermined engine speed range based on a steady-state difference between the desired and current engine torque to reduce the steady-state difference to zero. The adjusted torque difference may be limited by a maximum-engine-torque-available parameter and a minimum-engine-torque-available parameter, which is based on an operating temperature, such as the engine coolant temperature. The system and method may also include controlling spark to rapidly reduce current engine torque to the adjusted torque difference value.

Abstract: A method is disclosed for controlling an internal combustion engine in a vehicle powertrain. A filtered driver demand for torque at vehicle traction wheels is used to determine an engine torque command. The engine torque command is initialized to a percentage of a target engine torque as a function of variables that may include a smoothness factor.

Abstract: A method is disclosed for controlling an internal combustion engine in a vehicle powertrain. A filtered driver demand for torque at vehicle traction wheels is used to determine an engine torque command. The engine torque command is initialized to a percentage of a target engine torque as a function of variables that may include a smoothness factor.

Abstract: A control method is disclosed for maintaining a calibrated minimum load for an engine in a vehicle powertrain with an engine. The possibility of engine misfire due to low engine loads is reduced. Further, undesired high temperature of an engine exhaust gas catalytic converter due to prolonged operation of the powertrain at low engine loads is avoided.

Abstract: A method for operating a vehicle to reduce exhaust emissions is provided. The vehicle includes an engine, a motor, a battery for operating the motor, and a catalyst for reducing exhaust gas emissions. The vehicle is operated in a first mode when at least one predetermined condition is met. The first mode includes providing at least some of the desired vehicle output power with the motor. The engine is operated to quickly increase the temperature of the catalyst when the output power from the battery is within a first predetermined range. When the output power of the battery is outside the first predetermined range, the operation of the engine is adjusted to drive battery operation into the first predetermined range. When the at least one predetermined condition is not met, the vehicle is operated in a second mode based at least partly on driver demand and battery requirements.

Abstract: A vehicle and method are provided that determine a misfire torque limit for an engine in the vehicle. The vehicle includes an electric machine operable to provide torque to the engine. The method includes commanding the engine to operate at a predetermined torque and a predetermined speed, thereby putting the engine in an idle state. An output torque of the engine is then determined while the engine is in the idle state. A torque offset, defined as the difference between the torque command and the determined engine output torque, is also determined. The misfire torque limit for the engine is then determined based at least in part on the torque offset.

Abstract: A vehicle and method are provided that determine a misfire torque limit for an engine in the vehicle. The vehicle includes an electric machine operable to provide torque to the engine. The method includes commanding the engine to operate at a predetermined torque and a predetermined speed, thereby putting the engine in an idle state. An output torque of the engine is then determined while the engine is in the idle state. A torque offset, defined as the difference between the torque command and the determined engine output torque, is also determined. The misfire torque limit for the engine is then determined based at least in part on the torque offset.

Abstract: A method for operating a vehicle to reduce exhaust emissions is provided. The vehicle includes an engine, a motor, a battery for operating the motor, and a catalyst for reducing exhaust gas emissions. The vehicle is operated in a first mode when at least one predetermined condition is met. The first mode includes providing at least some of the desired vehicle output power with the motor. The engine is operated to quickly increase the temperature of the catalyst when the output power from the battery is within a first predetermined range. When the output power of the battery is outside the first predetermined range, the operation of the engine is adjusted to drive battery operation into the first predetermined range. When the at least one predetermined condition is not met, the vehicle is operated in a second mode based at least partly on driver demand and battery requirements.

Abstract: The present invention provides a system and method for starting a vehicle in a cold temperature environment and minimizing the time spent by the vehicle within a resonance frequency zone during operation. The present invention includes a method of starting a vehicle engine comprising adjusting the speed of the engine during an engine start mode in accordance with a fixed value threshold. The method also includes determining whether the engine speed has reached the fixed value threshold or whether a time-based threshold has been reached. The method further includes transitioning out of the engine start mode into a normal operating mode when either the fixed value threshold or the time-based threshold has been reached.