Riviera V6-3.8L SC VIN 1 (1995)
Boost Control (Bypass Open)
DESCRIPTION
The boost control system regulates induction boost pressure during rapid deceleration, under very high engine load situations and anytime reverse
gear is selected.
OPERATION
Under most conditions, the PCM commands the boost control solenoid to operate at a 100% 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 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% 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% duty cycle ("OFF")
at all times.
RESULTS OF INCORRECT OPERATION
An open CKT 1724 or boost control solenoid valve stuck open will cause reduced engine power, especially during wide open throttle operation.
CKT 1724 shorted to ground, boost control solenoid valve stuck closed or a restriction in the boost source signal hoses will cause full boost to be
commanded all times and a possible overboost condition during high engine load situations.
A restriction in the vacuum signal hose to bypass valve actuator will cause a rough idle reduced fuel economy.
