ByPass Valve Actuator


The ByPass valve contains the entry point and exit point of air (pressure),
Which one is going to where ?

To test the sealing and correctness of the bypass valve, I connected the bottom line in a low pressure of 4psi (0.3 bar)
And he opened the leg completely,
How can I fix the system that will open at 0.7 - 0.9 bar pressure?


  • 2.jpg
    16.6 KB · Views: 289


Stupid Bollocks
top port (V) to inlet of the charger 2nd port open
there's a proper tool for setting the preload on the bypass valve

boost control on the cobalt lsj
solenoid. The boost control solenoid is normally an open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 99-100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. As engine load is increased, engine vacuum is decreased, causing the spring in the bypass valve actuator to overcome the applied vacuum, closing the bypass valve and allowing the boost pressure to increase.

The bypass valve starts to close when the vacuum measures 250 mm Hg (10 in Hg) and is fully closed at 90 mm Hg (3.5 in Hg). When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet.

Supercharger boost pressure is regulated to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) limits boost pressure to 83 kPa (12 psi). The PCM disables boost under the following conditions:

• When reverse gear is selected
• When the engine coolant temperature (ECT) is excessively high
• When drivetrain abuse is detected
• When the vehicle is decelerating
• If an intercooler pump failure is detected
• If the intake air temperature (IAT) sensor 2 becomes excessively high
• Under heavy load in first and second gear at engine speeds above 5,800 RPM
Boost System Diagram
(1) By-Pass Valve Actuator
(2) Boost Signal
(3) Boost Control Solenoid
(4) Boost Source
(5) Supercharger
(6) Intake Plenum
(7) By-Pass Valve
(8) Throttle
(9) Air Cleaner
(10) MAF Sensor
(11) Inlet Vacuum Signal

hope this helps


Stupid Bollocks
to test is the bypass is faulty you would need to connect a vacuum gague to the (P) port while the engine is running to see if the internal diagram is split
here is a defective bypass valve