No boost, need verification!
 

Hello all, first post, what an informative forum! I've got a 98 SSEi with no boost on the guage (goes up to 0, but that's all). I looked at all the posts on this, but need verification of what it is. When the engine is off, the BCA is extended down. When I start it, the BCA pulls the lever up to it's "vertical" position. When I throttle it, it moves in and out. I unhooked the line off of the top of the BCA, no boost. I unhooked the line going from it to the BCS, still no boost. I unhooked the line on the other side of the BCS, still nothing. I checked the T fitting under the charger nose and all lines seem to be in great shape. Is it my BCS that's bad? In all situations above the guage goes up to "0", but not past it. Is the lever that the BCA moves the waste port? Thanks in advance for your help!!

Sounds like the bypass valve is working to a degree.

It is possible that the PCM isn't allowing the valve to close fully, however this would usually be under knock retard situations.

I'm assuming this worked fine and this is a recent issue? Any low octane fuel added by mistake?

This may be a stupid question, but do you have the supercharger belt on?

Belt is on and does not slip. Tension seems OK. I can hold the BCA one way or the other and rev it and there is no change. Does the BCA dump the boost pressure or hold it when it pushed the rod down?

When you pulled the top line off the BCA, did the rod go all the way down?

Yes, it does.

Actually, I just bought the car in August, and have never owned an SSEi, so I didn't know the difference, until I rode in one WITH boost! Holy crap! So I started to check into it.

If the actuator fully travels when you pull that top vac line, you have either a vacuum leak on the BCS side, a bad BCS, or the PCM is limiting boost for some reason.

SOunds good. I think I'll replace the BCS (relatively cheap). Vacuum lines all look excellent. Where is the PCM? I don't think I asked clearly above, does the BCA dump the boost? I'm just trying to understand the system. Thanks for all your help! :D

Try this page (pic links are screwy, but you'll get the picture):

http://www.bonnevilleclub.com/forum/.../bearings.html

You'll see the bypass valve. You can also see the arm the BCA attaches to in order to figure out which direction is bypass, and which is boost. ;)

When the arm is DOWN (horizontal) you should be in boost. When the arm is up, you should be in bypass. At idle, it should be fully up until you remove vacuum to the top BCA port, then it should go fully down.

If it travels fully with this test, the problem is very likely the BCS.