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Help adjusting Turbo XS boost controller


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I installed a used Turbo XS deluxe unit with dual adjustments. Since it was used, I didn't get any instructions. Took it for a test spin, acceleration was good, then I looked at my boost guage reading 15 PSI. I tried turning the big knob both directions and closing the fine adjustment, it didn't seem to change the boost level. I would like to run it at 8 to 10 PSI, Does anybody know how to do the initial set up and dial in process? Or what is a safe level? I know about the fuel cut but using this for rally cross there will be no long pulls, just short bursts, so I'm hoping not to find the fuel cut.

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Turning the big knob in (to the right) should raise the boost, it puts the spring under more compression and requires more pressure on the ball to push the spring back.

 

 

Opposite affect by turning it to the left.

 

Is it possible the MBC has been installed backward?

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Is the big knob turned with a wrench? Does it have a allen screw to lock it? What about the one on top, is it just an allen screw or does the whole top turn? I know, dumb questions. It could be backwards but I paid attention to the arrow. Does the stock controller need disabled?

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Sorry I can't be more specific, I'm not well versed in the TurboXS controllers.

 

But I can tell you that the stock controller does not need to be disabled. Its purpose is to allow full boost under varying conditions and elevations. (read : varying ambient air pressure)

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theres a stock boost controller? i have the plain turboxs boost controller. i hooked mine into the line that goes between the wastegate and some pressure line that came from something mounted on the passenger side fender. works like a charm!

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theres a stock boost controller? i have the plain turboxs boost controller. i hooked mine into the line that goes between the wastegate and some pressure line that came from something mounted on the passenger side fender. works like a charm!

 

That thing on the fender is the stock controller

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on the 87+, you can run it with the line from the pressure side to the wastegate as well..

 

That simply bypasses the factory controller, which is non adjustable and exists specifically to melp make sure the car sees full boost under all sorts of air pressure conditions.

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Okay, the brass fitting on the side of your boost controller is the course adjustment and the allen screw in the top is the fine adjustment.

 

The course adjustment is controlled by an allen screw inside the brass knob. It is important to remember that this screw is a left hand thread, so it tightens and loosens backwards.

 

The easiest way to get started on this controller is to disconnect it from the lines you have it hooked up to and pull it out. Then loosen the course adjuster all the way (it will not come out). Shake the boost controller and listen for the ball rattling inside. Slowly start tightening the screw down just until the ball stops rattling when you shake the controller. Then, tighten the fine adjustment all the way down, and open it back two full turns. Drive the car and check your boost levels. One turn of the fine adjuster should be equivilant to 1 psi of adjustment. If you are still running too much boost, you may have to loosen the course adjuster screw slightly.

 

I hope this helps.

 

Kent

www.prestigesubaru.com

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