jwa4378

hmmm.... well, I went over to my friend's house and gave his 7# spring a try. Still surging.

The Wastegate is running off of the FPR vacuum line, and the BOV was running off the line just rear of that (NOT the PCV line, like I originally thought). The guy at the shop commented on how the diameter of this line is thin, and the fact that it is at the very back of the IM could create a problem. I went ahead and re-connected this line like normal, and tapped into the secondary air line just forward of the FPR vacuum line on the IM. Much thicker line. I tapped into it with 3/8" vacuum tubing to run to the BOV (what size tubing is everyone else using?). Tested it, still surging.

The last thing the guy recommended was to seal off the secondary air line at the IM, and use nipple where the line returns back to just rear of the TB. This would give me a direct vacuum source, with a THICK nipple, RIGHT behind the TB. This makes sense to me... can someone please verify before I blow anything up?

Also, There is an open nipple coming out where the secondary air pump used to be... it is the lower of the two lines that run along the fuel rail. Should this be capped? Not sure if its part of the secondary air system (and possible vacuum leak), or if its part of the TB warmer (which was bypassed).

Thanks!

John

synapse

[QUOTE=jdnissanz,Sep 2 2008, 06:12 AM] Umm I think you have the wrong spring.

jwa4378

Hey-

I take it you work for Synapse engineering? lol

I can't view the file on my phone. I will post up when I listen over lunch @ home. The symptoms sound similar... delayed actuation.

The BOV was originally run off the rear-most nipple on the IM (rear of FPR line). I moved it to the secondary air line0 just forward of the FPR line. It got better (about the same as when it was still running off of the rear-most nipple with the lightest Tial spring installed... local FD owner let me test it out). So its not the spring...

I have abother thread out about how to properly hook this line up, and about possibly deleting the secondary air line from the IM (just forward of FPR line), but there is a T under the IM, and I don't know where its sending vacuum... whether that is also part of the secondary air system or something more vital...

Thanks!

John

jdnissanz

I'm sorry but look at Synchronic BS and you will see a video of how the Tial 50mm can perform very well. I like the Synchronic BOV, but I don't like false advertisement, which is why I went with the Tial.

http://www.youtube.com/watch?v=8-JTfgpFKrM

James D.

jwa4378

Yup. Its flutter dump 100%. Not as loud, but I am probably running lower boost than that Subie...

I think finding the most pure vacuum source possible will fix it. I am trying to tap into the secondary air return nipple on the IM, just rear of the throttle body, but I am not sure where to cap the supply side (where it exits the manifold just forward of the FPR vacuum line, or where it T's off under the manifold (I don't know what the other side of the vacuum T goes to)... I am also going to be using 11/32 reinforced line vs. the 3/16 non-reinforced that is on there now (it feels noticeably flimsier when under vacuum). It "got better" when I relocated the vacuum lines closer to the throttle body, but did not fix it completely. I am pretty sure the nipple just rear of the throttle body will be more than enough (it also uses a thicker line from the factory than the lines up top).

I don't want a pissing contest in this thread. Tial's 50mm will work, but it will be a bit more finicky to get running. Once its up and running, it will work 100% of the time, like any other Tial. Synchronic is great, as it can be tuned WAAAY beyond the spring. The shop I bought this from does not carry Synapse gear, so that made my decision a lot easier. to both products.

John

synapse

[QUOTE=jdnissanz,Sep 4 2008, 03:14 PM]I'm sorry but look at Synchronic BS and you will see a video of how the Tial 50mm can perform very well.

AndyFloyd

good explanation there.

jwa4378

I am thinking it is a vacuum issue, as the valve is opening, so it is getting the amount of vacuum necessary to actuate the valve, its just not getting sent down the tube fast enough (try blowing through the tube, there is constriction resistance). I am not seeing an increase in vacuum from when its surging to when its opening. It just seems like the signal is getting there late.

Like you said... the pulling force of the vacuum on the back of the diaphram + the force of the comrpessed air in the IC pipe needs to be greater than the Tial spring. If its opening late, and vacuum is staying constant, and the IC pressure is dropping due to surging out the intake pipe, it makes no sense why it would open at all... It does open, so I think that there is something wrong with the vacuum signal.

Moving the line from the rear of the manifold to the middle almost solved the problem. Moving it to just rear of the throttle body I would hope would cure it (if a similar improvement is noticed, it should be). It used to surge 3 times before it opened prior to moving the line, now it opens maybe 1/2 sec late (vs. 2-3 seconds late prior to moving the line).

Also, eliminating the secondary air system vacuum supply from the system will probably reduce any other pressure problems.

Can anyone answer my question about the vacuum T under the intake manifold?

John

synapse

Just a side note: compressor surge generates a pressure spike in the intercooler piping, not a drop. The quick pressure build should "theoretically" help the BOV open more and flow more. But if the valve isn't open at all (ie you haven't overcome the preload force of the spring), then there is no mass flow across the valve helping it lift more, nor is there a pressure differential present in order for a faster rate of diffusion to help eliminate surge.

BTW, you aren't seeing any effects on the gauge because that is after the throttle.

jwa4378

That makes sense, but it still does not explain why its opening post surge, as opposed to before the pressure spike clears the pipe (that is the "surging" noise we are hearing... the pressure escaping not being built).

I am also going to re-do me vacuum lines this weekend (noticed only 9.8# vacuum this morning, so something has to be up).

Any input on that T line under the manifold?

John