Grand Prix V6-191 3.1L (1989)
Wastegate Solenoid: Description and Operation
Turbo Wastegate Solenoid
The wastegate solenoid is normally closed, but opens to bypass exhaust gas to prevent an overboost condition. The wastegate will open when pressure is
applied to the actuator, and is controlled by a wastegate control solenoid, pulsed on and off by the ECM. Under normal driving conditions, the control
solenoid is energized all the time which closes off the manifold pressure to the wastegate actuator. This allows for a rapid increase in boost pressure. A
boost increase will be detected by the MAP sensor, and the ECM will pulse the wastegate control valve. Manifold pressure will then be allowed to pass
to the wastegate actuator, and the actuator will open the wastegate. This will prevent an overboost condition on acceleration. As boost pressure
decreases, the ECM closes the control valve and the actuator bleeds off through the vent in the control valve. If an overboost does exist as indicated by
the MAP sensor, the ECM will reduce the fuel delivery.
