Boost controller programming question

1259 Views 8 Replies 4 Participants Last post by defiler, Sep 22, 2008

Stealth

Discussion Starter · Sep 20, 2008

I dont understand why the boost settings A and B are in duty cycle? I figured I would just set the pressure that I would like them to open at.

What I am not understanding is how the duty cycle relates to boost level. Can anyone explain how the boost settings A and B are going to relate to pressure?

Or am I reading it wrong and I just need to set the spring pressure to whatever my desired boost is?

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Stealth

Discussion Starter · #2 · Sep 20, 2008

Well, I found this but it seems like a corny ass way to set boost level.

http://forum.aempower.com/forum/index.php/topic said:
Setting up the Tru-boost

1. With the gauge powered up and the engine running hold the left button for 2 seconds and switch to Run Mode A.
2. Then hold both buttons for 2 seconds to get into program mode.
3. Press the left button once to get into program mode A. Once in the Program mode for setting A, start from 10% duty and add 2% duty at a time until the desired boost pressure is achieved. Do a full-throttle pull in a high gear and watch for boost spikes. Please remember depending on the engine/turbo/manifold design you might not get any boost increase until you get to 20-30% duty. In this case you can add 5-10% at a time until you get closer to your desired boost level.
4. Once you get to your desired boost turn the key off and back on or press both buttons till you are out of program mode.

5. Hold both buttons again to get into program mode and keep pressing both buttons till you get to the sPr/Gae option (waste gate crank pressure). You can see page7 to follow the tree structure. To help the turbo spool quickly, the Tru-Boost can hold the solenoid at 100% duty if boost is below this pressure. Think of it like the electronic equivalent of a wastegate spring. Start from 1psi and increase the sPr/Gae value 1 psi at a time until you go over your desired boost target. For example: If your target boost is 15psi and you add 1 psi to your waste gate crack pressure and your boost goes up to 16psi you will need to decrease the number for sPr/Gae.

Depending on your turbo, manifold, engine characteristics or combinations you might end up with boost pressure dropping off at high RPM or Boost pressure spiking high at high RPM. The Tru-Boost controller can't compensate for this, it was designed to be a simple boost controller without too many options. Just make sure you follow the steps above to accurately and quickly set up your Tru-Boost controller.

It appears that it adds the duty cycle on top of the wastegate spring pressure, which IMO is rediculous. I should just be able to set the pressure I would like the valve to open at and have it do the calculations for me :shrug:

Oh well. I guess I cant set my boost controller until the motor is broken in since Im not willing to do full throttle pulls to over 10 PSI when I only got 30 miles on the motor. :sigh:

So if my calculations are correct at 90% duty cycle on a 7psi spring i would only be able to boost just under 14 psi? Seems kind of silly. That means I would have to set a WG spring at 10 PSI just to get 17 lbs of boost (desired to make my dyno run at)

Someone tell me I am wrong please.

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Stealth

Discussion Starter · #3 · Sep 20, 2008

As Im reading along now it appears that people with 14 psi springs are setting their SPr (spring crack pressure) to like 4 psi so that the tru boost closes the valve earlier.

If that is the case them Im to presume the duty cycle is running off what you have your FUL (full scale) set to. (which would seem much more practical)

I am confooooosed

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Stealth

Discussion Starter · #4 · Sep 20, 2008

Ok, I think Im talking myself into the answer here.

http://forum.aempower.com/forum/index.php/topic said:
Your car is acting like that because the boost controller is not setup correctly. In setting A and B, those numbers mean duty cycle, not boost pressure. 10% is minimum boost (wastegate spring pressure) and 90% is maximum boost. Leave your SPR setting at 1psi, setup your setting A and B. Start off at 10% and slowly work your way up until you reach your desire boost level. Once setting A and B is set, increase the SPR setting by 1psi at a time until you get boost spike, then put it back to the previous number. The SPR setting is usually fairly low.

This would explain it all besides the question, what dictates max boost? He states that 10% duty cycle is basically Spring crack pressure, but he never goes into details on what dictates max boost. :sigh:

Im just going to have to wait and figure it out.

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KING6

· #5 · Sep 20, 2008

Thats to much thinking for increasing boost.

lol, I got 3 dials, gain, low boost, high boost. and little slash's for increments.. no accuracy, all guess and go.

whats the little solenoid that controls boost look like?

btw, Im no help

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Stealth

Discussion Starter · #6 · Sep 20, 2008

Its a mini mac valve with a AEM sticker on it :lol: I could grab one from work for a spare

From what Im reading this is kind of a guess and go as well, it just has electronic instead of dials :shrug:

One other thing I was reading I dont really find to fond of, is that the controller actually sends a PWM out to the valve all the time, and it will tell me if the coil on the valve fails on my gauge. Its a nice option but I see valve life decreasing and crazy ticking solenoids. :lol:

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Turk

· #7 · Sep 22, 2008

My boost controller is the same, it describes it as % of total compressor output. I started at 0% and added 5% till it started lifting boost. By 15% i have 5psi (from 4 spring). 25% is like 5 psi, 35% is 7psi, and 38% is 8psi. It would be nice to just choose boost pressure in PSI, but they like making it diffiuclt. I know the more expensive models let you set boost in psi. Those are my 4 settings that I can choose from. Digital as well like yours. It isnt hard to setup, just have to go up in increments watching the boost gauge till you get the boost where you want it to be on each settting..

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Stealth

Discussion Starter · #8 · Sep 22, 2008

I mean its stupid. The thing reads PSI, yet it doesnt understand how to turn an output on at a given PSI. Absolutely the dumbest thing I have ever heard.

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defiler

· #9 · Sep 22, 2008

WOuldnt a simple Hobbes pressure switch work just as well in theory? Turn on/off the controller at certain pressure levels?

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