You are right !!!

My boost (although it took longer to get there than I remembered) was the same just shy of 15 lbs

But my vacuum right before the BPV change was never more than about 4 lbs

What ever happened to my orig BPV would not allow a adjustment that would have the butterfly fully closed.

After= Boost still just under 15 lbs of boost (I do think quicker to get there)
and vacuum now 12 at idle and almost 20 on coast down

 

Just curious, did you ever get an SEL. The reason I ask is the vacuum works the FPR & on some VGS mods it will throw a 0171 if the diaphram is bad.

 

I never got a SEL

 

i actually got better results by doing your deal and adjusting my own. the detroit is a nice spare though.

 

i personally wouldn't think so as your cylinders determine vacuum. so likely you'd test vacuum at the intake manifold. the bypass would be pulled open by this vacuum.

 

Spares = Gooooooood

 

The reason I asked is that happened to me last weekend. Idle vacuum changed from 18 in to 4 in hg and max boost peaked at 5 psi (was 15 psi). I am still trying to determine the cause and thought it might be the BPV.

 

I have a DT bypass valve. Complete waste of $, IMO. The original BPV had a good seal. I'd put the stock one back on if it wasn't such a hassle.

 

of a leak, but it also is what the original poster saild about his car. Check it out! At idle, you can get your fingers down by the BPV, and push it more closed. See if vacuum improves...

Matt

 

You were right, it was a leak. The hose to the fuel pressure regulator was off. That was a much easier fix than swapping the BPV. All is good now.

 

i see where y'all are goin' with this but if vacuum pulls the bypass open isn't it a mute point once it starts to open ?

 

You'd push it open to improve vacuum,

Matt

 

see this is where i get off. the hole in the tube for the vacuum sorce on the bypass valve is below the butterfly of same when mounted; so it's vacuum sorce toopen is all the way round through the s/c . so this coming summer i'm taking the front end off cause of an oil leak and you can bet some gaskets will be getting replased as well as a thorough inspection of all the mating surfaces of everything on this path. so how much should it be open at idle ? maybe this is the sorce of alot of the troubles; it's not very consistant.