Circuit/System Description
The BorgWarner™ dual scroll turbocharger incorporates a wastegate that is controlled by a pressure differential, that is determined by the engine control module (ECM) by means of a pulse width modulation (PWM) solenoid, in order to regulate the pressure ratio of the compressor. A charge air bypass valve also controlled by the ECM by utilizing a remotely mounted solenoid is integrated into the bypass valve to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the bypass valve is open during closed throttle deceleration conditions, the bypass valve allows the air to recirculate in the turbocharger and maintain compressor speed. Within a calibrated range during the closed throttle event or upon a wide open throttle command the bypass valve will then close to optimize turbo response. The turbocharger wastegate actuator has the following circuits:
- Ignition voltage
- Turbocharger wastegate solenoid control
At idle the turbocharger wastegate solenoid parameter is commanded to 0% by the ECM. When the engine load and RPM first increases under a wide open throttle, the turbocharger wastegate solenoid parameter should briefly be commanded as great as 90-100%. When the proper level of boost pressure is attained, the ECM will decrease the PWM of the solenoid to a range of 65-85%. As soon as the throttle closes the ECM will command the turbocharger wastegate solenoid parameter back to 0%, in order to allow the turbocharger waste gate to open from the air pressure ratio differential, there by reducing the speed of the turbine.