Abstract: Methods and systems are provided for adapting a compressor surge line in real-time. In one example, a method may include retarding a surge line in response to a number of surge events greater than a threshold number of surge events, and advancing the surge line in response to a number of aggressive tip-out events, that do not result in surge, greater than a threshold number of tip-out events.

Abstract: Methods and systems are provided for improving boost pressure control by adjusting a variable compressor recirculation valve. In one example, a method may include adjusting a position of a continuously variable compressor recirculation valve based on amount of sludge accumulation on the valve. The amount of sludge accumulation may be estimated based on a difference between total intake flow downstream of a compressor recirculation passage outlet but upstream of the passage, and total engine flow entering engine cylinders.

Abstract: Methods are provided for identifying degradation in components of a compressor bypass valve (CBV). One method comprises commanding a periodic signal to the CBV and indicating degradation of a throttle of the CBV based on changes in pressure at an inlet of an intake throttle in response to the periodic signal.

Abstract: Methods and systems are provided for diagnosing compressor bypass valve degradation. In one example, a method may include indicating degradation of a compressor bypass valve coupled in a compressor bypass based on intake aircharge temperature measured upstream of a compressor inlet via an air charge temperature sensor.

Abstract: Systems and methods are provided for reducing surge in a boosted engine system. One method comprises adjusting an opening of a compressor recirculation valve to allow a compressor recirculation flow based on a combination of a nominal compressor recirculation flow and a filtered nominal compressor recirculation flow. The nominal compressor recirculation flow may be calculated as a difference between a desired compressor flow rate based on a surge limit of compressor and an estimated throttle mass flow rate.

Abstract: Methods are provided for identifying degradation in components of a compressor recirculation valve (CRV). One method may include inferring degradation of the CRV based on adaptation of a compressor surge line outside an expected range.