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A few boost questions

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Old Oct 29, 2012, 08:36 PM
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A few boost questions

Hello i have an evo 8 with 3 inch dp, test pipe, and catback. I just finished installing my Aem Truboost and wideband. I heard that the 8 peaks boost around 19 psi from factory and tapers to somewhere around 16 or so. My car seems to only make 13.6 psi and taper down to 12 by 7k. Is this unusual or normal. My car also reads -17 vacuum, i noticed that most of my friends cars read -21 or close. Do i have a boost leak somewhere? Just wanted to ask before i check and find nothing.
Old Oct 29, 2012, 08:52 PM
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Pardon my ignorance, but is the AEM True-Boost a manual boost controller(MBC)?
Old Oct 29, 2012, 09:05 PM
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Sparky, the AEM True-Boost is an electronic boost controller.

To the OP, it sounds like you are currently running the wastegate pressure. I understand that you just finished "installing" the True-boost however I am wondering if you have actually tweaked it yet?
Old Oct 29, 2012, 09:24 PM
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Originally Posted by heel2toe
Sparky, the AEM True-Boost is an electronic boost controller...... OP, it sounds like you are currently running the wastegate pressure. I understand that you just finished "installing" the True-boost however I am wondering if you have actually tweaked it yet?
Thanks heel2toe, it seems like you are familiar with this True-Boost critter. Is it possible that the OP may be experiencing a programming glitch, or setup problem with that particular boost controller?
Old Oct 30, 2012, 05:50 AM
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Do you still have the AEM in the off setting? You need to select either A or B and set the duty cycle til you get your desired boost.
Also, it never hurts to do a boost leak test if one hasn't been done in a while.
Old Oct 30, 2012, 07:40 AM
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Originally Posted by 89Saleen141
..... I heard that the 8 peaks boost around 19 psi from factory and tapers to somewhere around 16 or so. My car seems to only make 13.6 psi and taper down to 12 by 7k. Is this unusual(?)....
1) First, do a boost leak test

2) Secondly, Disconnect the EBC, plug or cap off any open hose ends. Buy a couple feet of 4mm hose. Connect one end of the hose to the nipple on the WGA and connect the other end to the nipple on the compressor discharge tube(j-pipe) nipple.

Do a WOT run to see if you get the same 13.6 PSI boost reading.
Old Oct 30, 2012, 07:41 AM
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Originally Posted by 89Saleen141
..... I heard that the 8 peaks boost around 19 psi from factory and tapers to somewhere around 16 or so. My car seems to only make 13.6 psi and taper down to 12 by 7k. Is this unusual(?)....
1) First, do a boost leak test

2) Secondly, Disconnect the EBC, plug or cap off any open hose ends. Buy a couple feet of 4mm hose. Connect one end of the hose to the nipple on the WGA and connect the other end to the nipple on the compressor discharge tube(j-pipe) nipple.

Do a WOT run to see if you get the same 13.6 PSI boost reading.

Note: See the caution in my post #10 this thread below.

Last edited by sparky; Oct 30, 2012 at 07:55 AM.
Old Oct 30, 2012, 07:46 AM
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Do you have a wideband as well, or a tune your current mods? If not, I would leave that boost controller alone until you get one or both of those... Wouldn't want you to hurt your car...

Edit: misread OP has WB.

Last edited by boostedmkiii; Oct 30, 2012 at 09:16 AM.
Old Oct 30, 2012, 07:52 AM
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The tru-boost comes with instructions on how to set everything up using the 2 buttons on the gauge face. It's really easy to use once you get the hang of it.

It's always good to do a boost leak test when doing anything with boost controller, turbo, i/c piping, intake manifold, etc.
Old Oct 30, 2012, 07:52 AM
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Is the integrated digital gauge of the AEM True-Boost your only boost gauge? If so, then you wouldn't be able to run the test that I outlined above as it would leave you w/o a boost gauge if you were to disconnect your controller.
Old Oct 30, 2012, 09:00 AM
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Yeah, i just finished the boost leak test and it is fine. When i turn on the car the truboost reads off even though I have adjusted duty cycle A and my wastegate pressure. Yes i have a wideband and its running fine right now. Feels about as quick as it was withouth the truboost its just its weird that its only got 13psi to give.
Old Oct 31, 2012, 08:16 AM
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Even with the duty cycle turned up to 70% i'm not seeing any increase in boost. Why am I stuck at 13psi? I'm lost.
Old Oct 31, 2012, 10:37 AM
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If its saying off when you start the car then you don't have program A selected and that's why you adjustments aren't doin anything. You should be able to select A with the car on then it should work fine.
Old Oct 31, 2012, 07:17 PM
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No but when I turn it on to program A or B it still doesn't do jack.
Old Nov 1, 2012, 06:30 AM
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Just to make sure, you are only pressing and holding the left button for 2 seconds to change from OFF to A and then to B, correct?

Because if you leave it in A, it should be there still when you shut off and then turn the car back on.

And also just making sure, you have port 1 open, port 2 to the wastegate and port 3 to the boost source, correct?

Last edited by will1311; Nov 1, 2012 at 06:37 AM.


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