Hey guys-

I am having an issue with my 50mm Tial BOV surging. I re-arranged the vacuum lines last night (moved the BOV line from the rear-ward most nipple up to the one just in front of the FPR line). The FPR line is running the wastegate, and I have not seen any issues with that.


After swapping springs with a local FD owner (the 7# spring did not work, and we established that I have an 11# spring in there now, which should be fine, as I am seeing 11-12# vacuum on my boost gauge between shifts). I even swapped the line into the FPR line (and moved the wastegate to the rear-most nipple), wastegate worked, BOV did not. I am assuming that I need the most direct vacuum source through the thickest tubing possible.

The guys down at the shop said that I could cap off this nipple @ the manifold (the one just forward of the FPR line, as its part of my deleted secondary air system):


He then said I could run the BOV line off the return nipple, just behind the throttle body.

I am not sure if I can cap this nipple at the manifold, as there is a hard vacuum Y-splitter under the manifold, that routes some vacuum back toward the bell housing area... not sure if this is still secondary air-system related. Here is a pic of the Y-tube under the manifold:


Here are my questions:

1) Can I cap off the nipple just forward of the FPR nipple on the manifold, or does this serve a purpose other than the secondary air system (the Y under the manifold, what does it do?)?
2) If so, can I use the return nipple just rear of the throttle body as the BOV vacuum source?
3) If not, can I still use the return nipple just rear of the throttle body as a vacuum source (and instead cap the Y-distributor under the manifold)?

I am looking for the most direct vacuum source possible for this BOV, as that seems to be the source of my surging problem. I am going to be using 11/32 re-inforced line (like coolant line) to make sure it holds its shape under vacuum.

Thanks in advance! I just want to be 100% sure before I got changing / removing vacuum lines.

John

 

Mods, is it possible to cross-post this in the UTH forum? They might know what these vacuum lines do from the factory a bit better...

Just a thought.

John

 

Bump. So no one knows where this vacuum T is sending vacuum to under the intake manifold? Just wondering if its needed...

John

 

All I ned is to know what that Y / T fitting under the IM is diverting vacuum for... can it be deleted, or do I need to cap the secondary air return at this fitting in order to run my BOV off the secondary air return nipple...

John

 

It is hard to hook up a BOV improperly, but it is possible.

However, I think your issue is not the lines, but the BOV itself. Maybe it has to heavy of a spring and your car does not create enough vacuum.

 

Ya - Well, the 9# spring did not work either (lightest Tial makes). There is an 11# spring in there now.

I have determined that the vacuum T under the manifold is for the Evaporative Emission Canister and Purge Joint. Is this required for AEM EMS, or is it part of the Pulse Secondary Injection system (and can be removed)?

Once I get my vacuum sitting steadily @ 11+# of vacuum, them I will determine whether this BOV will work or not.

For the record, is there ANYONE on this board running this BOV at lower than 10psi? Just curious as to whether anyone has gotten it to work properly at low boost levels on the f20c. If not, I may end up requesting the shop change it out for an sequential BOV...

Thanks!

John

 

Bump for info on removing the vacuum line.

 

You shouldn't tee off the vaccum supply to the FPR, I did this on my evo and thank god for the EGT gauge the line worked itself off and I was running dangerously lean.

 

Well, that is where just about everyone pulls their wastegate vacuum from, or at least those I have seen.

I believe it is one of the better sources, actually, if you do not have an extra vacuum port.

And I am not sure why you would have had to put a t-fitting on an evo... they are turbo from the factory, so they should have a factory line, right? Their wastegate is just internally gated...

John

 

i was under the impression that the aft most intake manifold nipple is where bov's are tapped in. i think you were correct originally and like ya@inlinepro said, it's probably your bov not vacuum source.