Here's the story so far:

Used to have an S4 Turbo on my S5 TII motor. I have a manual boost controller. No matter how much I turned it up or down, it always boosted to ~5PSI. I then installed an S5 Hybrid turbo, and it still would boost to ~5PSI regardless of what setting the boost controller was at. So I did some searching on here, and someone mentioned that the controllers only work one way. So, I switched the lines around, and voila! Without even giving it lots of gas, it boosted up to ~11 PSI. So i was pumped, but turned it back down, because I didnt want to run that high. Now, I turned it back up again but its doing the same thing as before! It wont go past 5-6 PSI.

So, I figured the boost controller was the issue. So I bypassed it, by just connecting the two lines together, that way it would boost to whatever it wanted. I was very careful with the throttle, just so it wouldnt boost to something stupidly high and wreck something. But, alas, it again went only to 5-6 PSI.

Does anyone know what the problem may be? I would like to run around 10 PSI, maybe higher. The engine was rebuilt about... 6000 KM ago, and the turbo has about 2000 KM on it also.


A side note: My BOV (Apexi Dual Chamber) is so quiet, i can almost never hear it. I was told to adjust it, you loosen the top screw until ____ happens, and then tighten the nut and its good to go. Anyone want to confirm this, or fill in the blanks?

(I also posted this in the Single Turbo forum, but no one responded yet)

 

I had the same problem when I installed a Manual Boost controller on my JSPEC S5, it wouldn't let me boost past 7 psi (and I was Drag racing at the time), so I just removed it because the boost problems started after installing it.

I, too, have that Apexi BOV, but mine works good...has that "pshhhh" sound...

 

If the boost controller limits the air pressure to the waste gate (someone please confirm this) then bypassing it as you did will limit boost to the minimum setting of the boost controller.

To go to maximum boost, the line to the wastegate must be removed (please do not do this, as the boost may go too high.)

The blow off valve is most likely quiet because 5 psi is not much above the setpoint (if any) so it is not blowing off much charge air.

I do not have a turbo in my car yet, so I am only going on what I have heard.

I think I am right, but it would be better to have someone else confirm this.

 

Ya that definately makes sense about the boosting.. Silly me. So all this could be due to a faulty boost controller, correct?

Any ideas how to adjust the BOV so its working 100% properly?

 

I am having this similar issue. I was told that my car is running 13psi but I am not boosting over like 5. Check my post. https://www.rx7club.com/2nd-generation-specific-1986-1992-17/bov-problems-695227/ This sounds like the same issue that I am having. Any help would be great!!!

 

Hmm, I wonder if I am using the wrong line for my BOV also. Does anyone have the Apexi dual chamber BOV? Tell me how you got yours working properly!

 

Alright! It was just the boost controller. Bought a Turbosmart one today, and she works great now. BOV Still isnt very loud though....

 

Ok off subject a lil but my friends car was boosting fine one day then he turned it off then got back in it to go and it isnt boosting anything at all(s5 TII) stock turbo...well i took the line off the wastegate to see if it would boost anything but it didnt 0psi...wat could this be, the turbo crapping out maybe??