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How to lower boost?

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Old Dec 19, 2004, 05:40 PM
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How to lower boost?

Do I need an electronic boost controller to lower my boost, lower than stock.
Old Dec 19, 2004, 05:41 PM
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Curiosity, why? Another de-tuning thread? Not to pirate the thread, so heres your answer. No, you can lower boost from stock with any manual boost controller, but be prepared for the car to run less than consistent and not as intended.
Old Dec 19, 2004, 05:42 PM
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The lowest you can go is what the wastegate is at. On the Evo I believe that is right around 12-13psi.
Old Dec 19, 2004, 05:49 PM
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Why in the world would you want to do that for???,
Old Dec 19, 2004, 05:50 PM
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Originally Posted by feldguy
....be prepared for the car to run less than consistent and not as intended.

What? Any other time, I would not say this, because of how I drive, but since when does the Evo HAVE to be driven at WOT and always over 16PSI in order to be consistent? I'm not following your logic, unless you are simply joking and implying that you must drive the car to the limit every time you get in it (personally, I'm not happy unless I do that in my car, but it isn't required to keep the car running ).
Old Dec 19, 2004, 05:52 PM
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I have an MR I just installed a MBC and with it closed, it peaks at a tiny touch over 1.5 bar, and it still tapers down to 1.2-1.3bar , and if the valve is closed and by opening it I am allowing more boost how can I shut it down a ttouch, to 19-20psi

Even before the MBC it peaked the same, but I thought it should hold the boost to redline

I'm troubleshooting

reasonable enough
Old Dec 19, 2004, 05:56 PM
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Originally Posted by herbal77
I have an MR I just installed a MBC and with it closed, it peaks at a tiny touch over 1.5 bar, and it still tapers down to 1.2-1.3bar , and if the valve is closed and by opening it I am allowing more boost how can I shut it down a ttouch, to 19-20psi

Even before the MBC it peaked the same, but I thought it should hold the boost to redline

I'm troubleshooting

reasonable enough

Open should take the car down to wastegate pressure (11PSI).

Closed should take you as tight as the spring inside the MBC will hold.

I'm thinking that if you have all your hoses ran right (and both of the restrictor pills removed) that you probably have too high of a spring tension inside the MBC.
Old Dec 19, 2004, 05:59 PM
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The only reason i can think for lowering bost is economy, or if you have really crappy gas in your area.
Old Dec 19, 2004, 06:00 PM
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Originally Posted by 90GSX-03EVO
What? Any other time, I would not say this, because of how I drive, but since when does the Evo HAVE to be driven at WOT and always over 16PSI in order to be consistent? I'm not following your logic, unless you are simply joking and implying that you must drive the car to the limit every time you get in it (personally, I'm not happy unless I do that in my car, but it isn't required to keep the car running ).
Fair reply, my logic is simple. When I turn my boost down in my car, my car hits differnet boost levels all over the place. Essentially, it is counter productive in the sense that the fuel mapping is intended for the car to run one way, and with a MBC set lower, it will not be tuned correctly. Its not bad, but its a waste just the same. I like mine set at 19, all the way...to each his own.
Old Dec 19, 2004, 06:01 PM
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when i screwed it all the way open , it spiked over 25 psi, so I screwed it closed and thats where it acted like stock, with peaking and tapering, but If i cant close it anymore how do I lower boost
Old Dec 19, 2004, 06:07 PM
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Originally Posted by herbal77
when i screwed it all the way open , it spiked over 25 psi, so I screwed it closed and thats where it acted like stock, with peaking and tapering, but If i cant close it anymore how do I lower boost
Did you remove the restrictor pills and bypass the stock boost control solenoid?
Old Dec 19, 2004, 06:09 PM
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it was supposedly professionally done
Old Dec 19, 2004, 06:10 PM
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Originally Posted by feldguy
Fair reply, my logic is simple. When I turn my boost down in my car, my car hits differnet boost levels all over the place. Essentially, it is counter productive in the sense that the fuel mapping is intended for the car to run one way, and with a MBC set lower, it will not be tuned correctly. Its not bad, but its a waste just the same. I like mine set at 19, all the way...to each his own.

I have an HKS EVC 5. I have Mode A set to 15 PSI and Mode B set to 20 PSI. I can toggle between modes whenever I want, raising or lowering the boost at will and with ease. When the unit is turned off, the turbo presses to 11 PSI every time, from 3000 to redline, in every gear. When commuting, I usually just drive around with the EVC 5 turned off, but when I want to drive aggressively, I turn it on and go to work.
Old Dec 19, 2004, 06:10 PM
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if you have any pictures , I can see
Old Dec 19, 2004, 06:12 PM
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Originally Posted by herbal77
it was supposedly professionally done
For some reason, I don't think it was. It sounds like they just added a MBC in line with your stock boost solenoid, so that when it is open, instead of going to true stock (11 PSI) it goes to "OEM boost solenoid" stock. Also, when you close the valve, it runs higher than stock (much higher because the lowest the boost solenoid will let it go under WOT is 16 PSI, so you have less room to work with down low).


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