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.