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A Wide-Range Air-Fuel-Ratio (AFR) control algorithm was developed for production application in Direct Injection Gasoline (DI-G) powertrains. The algorithm controls AFR to a scheduled target by modifying open-loop fuel injection timing duration using a Wide-Range AFR sensor measurement for feedback. A physically based hybrid State Estimator design was used to account for event-based engine delays and time-based sensor measurement characteristics to determine the error between target and measured AFR. The State Estimator was designed to minimize algorithm size, calibration burden, and engine controller throughput demand. A time based, gain-scheduled Proportional-Integral control algorithm design was used to correct AFR errors. Non-physical estimation and control functions were designed for application with time-based updates to minimize engine controller throughput demand.

An event-based transient fuel compensator (TFC) algorithm was developed for production application on SPFI gasoline engines. The independent parameters of the TFC were related to fundamental mass-transfer principles from the research of Gilliland and Sherwood [1] to simplify cold-driveability and emissions calibration activities. A compact intake valve temperature model was developed to further simplify calibration. Digital Control Theory was applied to the calibration structure of the algorithm to clarify the relationship between compensator stability and parameter settings. In its final production algorithm form on a 2.4L DOHC engine application, the TFC met the required subjective cold-driveability requirements and emission standards with a significant reduction in transient fuel calibration complexity.