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aka mrubino83
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Discussion Starter #1
Yes, I searched. The related threads are like 7 pages long and none really address my issue specifically. Anyway,

Heres what I have tried so far:

1) Synapse DV in every possible configuration:push, Pull, A+B ports,
just A, and Just B-no luck

I Thought it was too stiff of a spring in the DV, so

2) Switched back to stock valve-same problem

THought maybe it was a weak vacuum signal to valve (T'd connection to
boost gauge) so;

3) New independent vacuum line directly to valve from intake
manifold-Same issue

4) Vacuum when car is warm is around -8 with the lowest value being -12. These seems spot on, right?

So now Im stumped. Im still thinking there is a vacuum leak
somewhere.

Thoughts?
 

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aka mrubino83
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Discussion Starter #4 (Edited)
What exactly is happening?
During shifts/letting off the throttle, it doesnt "cleanly" recirc the air. it goes "CH-CH-CH-CH-CH-CH-CH-CH". instead of "whoosh".:bowlol:

Where do you have the DV located?
See pic please, and keep in mind this is the same location with my previous turbo setup, which worked perfectly.
 

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During shifts/letting off the throttle, it doesnt "cleanly" recirc the air. it goes "CH-CH-CH-CH-CH-CH-CH-CH". instead of "whoosh".:bowlol:
And the stock BOV does the same thing? Does it happen when you lift off the throttle after a WOT pull or only after partial throttle?
 

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aka mrubino83
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Discussion Starter #9 (Edited)
Depends if PSI or mmHg :innocent:
I was using AP to measure vacuum, whatever unit it is was reading -8, Im assuming it was psi.

Anyway, what us healthy vacuum for our cars?



Edit:Just for reference, its most likely in/HG if its Std measurment. so -21in/hg= about -10psi which I think is right on for stock vacuum.
 

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aka mrubino83
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Discussion Starter #10
Have you double checked the pneumatic fittings? By chance could you PM or post for me an up close of the DV?
I can take a close up of them and shoot it to you tomorrow, but I think the valve itself is not the issue, becuase I switched back to the OEM valve and the same flutter occured.

And the stock BOV does the same thing? Does it happen when you lift off the throttle after a WOT pull or only after partial throttle?
Yes, stock BPV does the same thing. It happens at both partial and full throttle.

Another note:
I am running only WG boost right now (16 psi) for my break in map. Could it be that 16psi is too low of a boost pressure to open the valve?
 

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Could it be that 16psi is too low of a boost pressure to open the valve?
That should be plenty, and in the case of the Synapse in pull mode there is no expected minimum pressure to make it open.

It sounds to me like there's something wrong with your vacuum source. You sure it's not pinched somewhere?
 

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My DV does the same thing ch ch ch ch ch
:+1: Mine makes the same noise, letting off the throttle at partial boost. Went through all the settings and preload settings, Just started too assume it was normal.
 

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:+1: Mine makes the same noise, letting off the throttle at partial boost. Went through all the settings and preload settings, Just started too assume it was normal.
That's pretty normal with any compressor bypass valve. You can get rid of most of it with a Synapse if you really try, but then you end up with the valve being so easy to open that it reacts to light throttle adjustments while you're driving on the freeway and we're right back to square 1 with a thread about how to get rid of this stupid BOV flutter.

That's a completely different issue than compressor surge every time you let off the throttle, which is what it sounds like hotstix is dealing with.
 

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aka mrubino83
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Discussion Starter #16
That should be plenty, and in the case of the Synapse in pull mode there is no expected minimum pressure to make it open.

It sounds to me like there's something wrong with your vacuum source. You sure it's not pinched somewhere?
I agree that it should be plenty of boost to open the valve.

Im thinking vacuum too. I even switched to a brand new vacuum line directly from the intake manifold to the valve. Its definitely not pinched.

:+1: Mine makes the same noise, letting off the throttle at partial boost. Went through all the settings and preload settings, Just started too assume it was normal.
No, it shouldnt do that. My stock valve never did it. My DV never did it before (maybe occasionally if I let off right at the boost/vacuum transition, but thats it), but they are both doing it now, EVERY time. Somethings not right. I just dont know what it is.

Im thinking about making an appointment at Cobb and using their smoke machine/boost leak tester.
 

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(maybe occasionally if I let off right at the boost/vacuum transition, but thats it)
I've seen so many people let off at the boost/vac threshold with every shift every time they drive that I've basically assumed I'm the only person on the planet that doesn't drive that way. Especially with all the "OMG my Synapse flutters wtfbbqthisisbullshit" threads I've read.
 

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aka mrubino83
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Discussion Starter #18
I've seen so many people let off at the boost/vac threshold with every shift every time they drive that I've basically assumed I'm the only person on the planet that doesn't drive that way. Especially with all the "OMG my Synapse flutters wtfbbqthisisbullshit" threads I've read.
LOL. I know there are a lot of these threads around. Like I said, I read though most of them and it was all the same shit. So sorry if Im being redundant here, just trying to pick peoples brains and see if there is something basic that I may be overlooking. If not, than I m just going to go through every connection and leak test it.
 

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what about vacuum line connectors or T`s.. maybe one is cracked ?
 

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Try and switch the orientation of the valve first, so it dumps back into the intake. Secondly, loosen the set screw on the top. Finally, log your boost/WGDC/and correction. See if your car is trying to manipulate the boost during spool. For example, if you are requesting too high a load at a given spool RPM, the solenoid may be triggering causing the fluttering sound you hear. See if there is any change after the changes.

Good luck.

John
 
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