Did a 3rd gear pull and at around 5k it drops from 24 to 15psi
Did this 3 times
Just changed the belt
would the bypass just open mid pull or belt slip?

 

Belt slip could be possible, but it wouldn't cause that big of an decrease in boost.
Your bypass valve could possibly be messed up. That's kinda what it sounds like to me

 

Ya and it's a smooth 15 psi
Not fluttering like belt slip would

 

Ima say bypass valve then

 

Any way to test it?

 

See if there's any play in it.. other than that, no not really

There should be very minimal play at max




and by "it", I mean the metal shaft/rod







Edit: Ah yes, forgot about that VVVVV
You can plug the port coming off the bypass solenoid and the one coming off the bypass valve and see if it fixes your issue

 

pull the hose off the bypass and do a run.

 

by pass valve shafts can seize especially if meth has been put through the blower. In my experience they seize open. If you have a vacuum leak at the IM, the valve will open and close at idle and generally misbehave... if you pull the hose, just stick a plug in it, the valve dont care, the solenoid does and you dont want a vacuum leak there.

 

Did a run works fine If it happens connected pull the hose on the valve
As for the shaft being stuck i can actuate the valve by hand no problem
My idle has been surging but i believe it's do to the winter blend e85
All my vaccum lines look fine and connected

 

You should be able to actuate it.. But you shouldn't be able to move it back & forth & round and round. Kinda hard to explain the motion

 

Moved it around seemed good
Did 2 pulls no problem
Hope it doesn't happen again
Only a week or two before she gets garaged for
A little winter build cams springs balancing shafts and 1000s maybe a ported head

 

What cams are you going with?

 

zzp stage 2

 

Nice, I'll be waiting for a review on those lol

 

Still.the same problem what hose am i removing

 

The hose that goes to the bypass valve. Take the hose off right there but leave it attached to the solenoid which is to the right of the valve cover. Plug the hose don't worry about plugging the bypass valve nipple. You plug the hose so there's not a vacuum leak at the bypass solenoid.

 

Gotcha and if I have no boost loss my valves bad

 

belt slip. get a larger tensioner.

 

I have a larger tens. And a phenolic spacer
And it seems a little odd that i had the same pulley
Size (2.7) on my m62 for 2 years no issue and out the blue this happens

 

weak tensioner then.

 

changed my belt from a dayco i got from work to my original gm belt
problems fixed 25psi all day

 

^^^ u said it was not the belt like 200 posts before...well. glad u got it fixed. lol