# Help with HKS Variable Boost Controller



## nismo85z (Oct 8, 2011)

Alright, so its been about 2 weeks and i haven't bothered messing with it anymore. I can have the VBC all the way closed and I'll get 6 psi @ WOT, but when I open the VBC it goes down to 2 psi. I shortened the hoses as much as possible and mounted it right next to the intake. It's routed with boost-in and wastegate-out. It has the arrow pointing out so its kind of a no brainer to how it goes routed. I know its routed right since when i opened it, it was the only way that made sense. I guess what I'm going at is, does anyone think its a faulty VBC or do I "t" it anywhere or something? :wtf:


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## AZ-ZBum (Nov 21, 2004)

Supposed to come off the turbo. At least, that's how all boost controller instructions I've seen are done.


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## nismo85z (Oct 8, 2011)

That's how I have it. Turbo pressure in and outlet to wastegate. But I've heard or many putting a t with the turbo and wastegate and letting the outlet vent to the atmosphere. Keep in mind its a VBC not a mbc, so do u think it makes a difference?


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## AZ-ZBum (Nov 21, 2004)

What's a "VBC"? Do you mean "EBC"?


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## nismo85z (Oct 8, 2011)

No its a manual boost controller, but its an HKS variable boost controller.


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## AZ-ZBum (Nov 21, 2004)

And what do you boost at when you don't have the boost controller installed period?


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## nismo85z (Oct 8, 2011)

Closed 7-8. But open it goes to 2 no matter how open I have it it stays at 2.


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## AZ-ZBum (Nov 21, 2004)

I'm sorry. Maybe I wasn't clear... If you take out the boost controller and reconnect it as stock, what boost levels do you get? And are you reading the stock gauge or do you have an aftermarket gauge?


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## nismo85z (Oct 8, 2011)

I have an aftermarket gauge. When I take out the boost controller its runs at 4 psi but when I put it on and have it closed it goes up to 7. If I open it it goes down to 2-3 psi


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## AZ-ZBum (Nov 21, 2004)

Then it sounds like it's working normally and you have a boost leak. Did you replace the pop off valve?


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## nismo85z (Oct 8, 2011)

No well not yet, since I don't plan on running more than 7 psi for a while. So a boost leak will do that huh?


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## AZ-ZBum (Nov 21, 2004)

Stock, the car boosted at about 7psi. So if you aren't even boosting there without the boost controller, you have other issues.


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## nismo85z (Oct 8, 2011)

Actually from 87-89 the stove psi went down to 3-4 psi. Due to the turbo being a t25 instead of the t3 turbo.


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## AZ-ZBum (Nov 21, 2004)

nismo85z said:


> Actually from 87-89 the stove psi went down to 3-4 psi. Due to the turbo being a t25 instead of the t3 turbo.


No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. 


1984 to 1987 (yes, ALL 1987 models) used the T3 turbo. Which was suggested to be 6.7 (or about 7) psi. The 88 and 89 turbos (with the slightly higher 8.3:1 compression motors) used the T25. That was rated at about 4.5 psi stock.


Soo... By your name of "nismo85z", I would have to assume you have an 85 turbo. Which, by definition, even yours, is supposed to boost at about 7 psi.

So once again.... (for the slow people in this thread) .... and since you haven't stated you have something other than stock under the hood ...


*If you aren't even boosting there without the boost controller, you have other issues. *


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## nismo85z (Oct 8, 2011)

Nah homie its not an 85. I have an 88. So for the slow people its rated at 3-4 psi.


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## AZ-ZBum (Nov 21, 2004)

nismo85z said:


> Nah homie its not an 85. I have an 88. So for the slow people its rated at 3-4 psi.


Then you should probably have mentioned that somewhere in your posts. Your name is "nismo85z". So it stands to reason you're asking about an 85. So the slow person here is you for not pointing out that you had an 88 in the first place.

It's 4.5 psi. So you're boosting about normal without the boost controller installed.

If you can't get over 7psi, then it sounds like the POV is opening.


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## nismo85z (Oct 8, 2011)

Well we all know the definition of "assume", but anyway I'm not here to argue. I wanna get this fixed. If the POV is opening then ok that's fine its doing its job. But the thing is the VBC is closed not open in anyway. All connections are tied down with tie wraps, like recommended. Also is there anything that should be removed or disconnected like perhaps the boost sensor?


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## AZ-ZBum (Nov 21, 2004)

No. You don't have to remove anything else.


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## nismo85z (Oct 8, 2011)

Alright, so let's talk boost leak. Would this be from the vacuum of the boost gauge, or VBC. Or perhaps the old boost gauge?


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