Operation

Under most conditions, the PCM commands the boost control solenoid to operate at a 100 percent duty cycle (ON), keeping the solenoid valve closed and allowing only inlet vacuum to control the position of the bypass valve. At idle, full inlet vacuum applied to one side of the bypass valve actuator diaphragm counteracts spring tension to hold the bypass valve open. As engine load increases, reduced vacuum acts upon the spring tension in the bypass valve actuator, causing the bypass valve to close and increasing boost pressure. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle (OFF). This opens the solenoid valve and allows boost pressure from the intake manifold to counteract the spring tension in the bypass valve actuator, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet. With reverse gear selected, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle (OFF) at all times.