Circuit/System Description

The dual-scroll turbocharger incorporates a wastegate that is controlled by the engine control module (ECM) by means of a pulse width modulation (PWM) solenoid, to regulate the pressure ratio of the compressor. An ECM controlled compressor bypass valve, which uses a remotely mounted solenoid, is integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. The bypass valve is open during closed throttle deceleration conditions to allow air to recirculate in the turbocharger and maintain compressor speed. The valve closes, within a calibrated range, during closed throttle events or wide open throttle commands, to optimize turbo response.

As engine load and speed increase, the turbocharger bypass solenoid valve is commanded ON by the ECM. As soon as the throttle closes, the solenoid is commanded OFF to allow the bypass valve to open and allow the turbocharger air to recirculate to prevent compressor surging.