I have a 2000 ssei and the SC is not maing noise but sesm not to be operating. The guage shows NO boost. Any had this problem, could it just be the by pass valve? :(

No boost when? None at all, none at idle?

You should only see positive pressure when moving and giving it some gas. If the SC quit working, it would probably make some horrible noises, and it would be extremly rare for it to happen.

Could be the boost actuator (black cylinder) is stuck, or the boost control solenoid (little box next to the actuator) has gone bad and is always dumping the boost.

no boost at all the guage never gets to 0, that is why i think a valve must be bad, the SC is not making nay noise.

Try this:
Take the little rubber hose off the bottom port of the actuator of the bypass valve and loop it back on to the second filtered post on the solenoid and take it for a drive. If the solenoid is bad, this test will show it cause you are disabling it'* ability to dump boost.

thanks i will give it a try

Check the vacuum line under the nosedrive of the Supercharger. It'* known to come disconnected or break. Check ALL the vacuum lines under the engine cover.

If a vac line was off, the car proably would not idle correctly (or even stay started).