Abstract: A method of controlling an internal combustion engine is described. The engine is capable of operating in at least two engine operating modes. As an example, the engine can operate in a stratified or a homogeneous combustion mode. The engine operating mode is selected based on a determined atmospheric pressure.

Abstract: A method of continuously estimating barometric pressure values for use in an engine control system. The vehicle includes an manifold absolute pressure (MAP) sensor, ambient air temperature sensor and a throttle position sensor. The method comprises the steps of determining the manifold absolute pressure, ambient air temperature, and throttle position. When the throttle position is at wide-open throttle, the method generates a barometric pressure value ({circumflex over (P)}anew) as a function of the manifold absolute pressure value (P) and previously estimated barometric pressure. Otherwise, the method generates a barometric pressure value as a function of the manifold absolute pressure value (P), and an estimated intake manifold pressure ({circumflex over (P)}) and estimated mass airflow (). In a further embodiment, a mass airflow sensor is also used to generate the estimated barometric pressure value when the engine is not operating at wide-open throttle.

Abstract: An idle speed control system for a direct injection spark ignition engine controlled to operate in either homogeneous air/fuel modes or stratified air/fuel modes. When operating in a stratified air/fuel mode, engine idle speed is controlled by controlling the engine air/fuel during unthrottled operation. When operating stratified and also throttled, engine idle speed is controlled by both controlling air/fuel and controlling the throttle. When operating in the homogeneous modes, engine idle speed is controlled by controlling both the throttle and ignition timing.

Abstract: A vapor recovery control system for a direct injection spark ignition engine is used to purge vapors in both a homogeneous air/fuel and stratified air/fuel mode. When purging vapors in a stratified mode, a portion of the cylinders receive purge vapors and operate in a homogeneous mode while the rest of the cylinders continue to operate in a stratified mode.

Abstract: A mode control system for a direct injection spark ignition engine is controlled to operate in either homogeneous air/fuel modes or stratified air/fuel modes. When transitioning from homogeneous to stratified mode, the throttle is used to adjust manifold pressure to a level where it is possible to operate in a stratified mode with a torque equal to that of the homogeneous model. When transitioning from a stratified to a homogeneous model, the throttle is used to adjust manifold pressure to a level where it is possible to operate in a homogeneous model with a torque equal to that of the stratified mode. During the transition, other engine operating conditions are used to assist in controlling engine torque.

Abstract: An idle speed control system for a direct injection spark ignition engine controlled to operate in either homogeneous air/fuel modes or stratified air/fuel modes. A desired idle speed is set to optimize fuel economy and avoid rough engine operation during various air/fuel operating modes. During rough idle conditions and non stoichiometric air/fuel operation engine air/fuel is enriched until either rough idle ceases or a rich air/fuel limit is reached. During smooth idle operation, and non stoichiometric air/fuel operation, engine air/fuel is enleaned until either rough idle occurs, a lean air/fuel limit reached, or desired fuel economy attained. After the lean limit is reached, and when operating in a non-stoichiometric non-stratified air/fuel mode, and when not operating at desired fuel economy, ignition timing is advanced until an advance limit is reached and desired idle speed is thereafter decreased.