Maft-Pro boost control issues...

johnnyddn

New Member
Jul 16, 2006
56
0
0
Las Vegas
I'm having trouble with Maft-Pro boost controller holding the PSI Set. Here are my current settings:

PSI Start - 11 psi
DC% Start - 50%
PSI Set - 14 psi
Gain - 10

The turbo will spool quickly to 14 psi but then once it hits it backs off quickly to about 7 psi. I've tried adjusting the duty cycle % up to about 65% down to 40% and noticed no real changes. I've also tried lowering the gain to ~4 to see if that would help. I'm just trying to get the controller set up so that it holds about 14psi at WOT and not spike all over the place.
 

Supra

New Member
May 11, 2005
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Rockford, IL
I wrote this a while back. You might find some of it useful. It may be for ver. 4.4. I don't remember for sure.
-Rich

*****************************************************
The MAFT-PRO boost control is pretty easy to use. It's almost the same as the AVC-r. The 'problem' (for me) was that the start duty default was too low, like 20% and my actuator was too loose. I tightened the actuator to 13psi without the MAFTPRO. When the start duty was 20% (low), nothing seemed to work as described. I brought that up to 60-80% and everything started to work as the book described.

Based on what I know about the AVC-r and the MAFTPRO, I'll toss the following intot he mix and see what turns up:

What the MAFTPRO manual should say about boost control is set your actuator to the minimum boost you want to run WITHOUT MAFTPRO correction. Then set your target PSI to what you want (19psi), set Start PSI to 3 psi less than that (16psi), set start duty to 50%, set your TPS and RPM to slightly above normal cruise, set your gain to "10".

****This means you will build boost quick on the bottom (until Start PSI is met), but the actuator will start opening too soon, and too quickly. <- safe

Do a third gear pull and log your boost. The line for solenoid will spike when the turbo is trying to build boost (100% solenoid duty). AFTER THAT - If the line goes up raise your start duty. If the line goes down, lower your duty. Try to get a line that starts out fairly level. If you boost goes to target and then drops raise start duty. If you boost spikes, lower start duty.

****Adjusting start duty adjusts the amount of air getting to the solenoid/actuator *initially*. The gain controls how quick the solenoid can self adjust thereafter. For now, you want to adjust this percentage to get a level line after the spike.

Once the solenoid line is fairly level after the spike, raise the Start PSI until you get a little boost spike. Lower it a bit to remove the boost spike.

****Similar to the above. On a large, laggy turbo you can build boost fast, then slam the actuator with alot of air at the last minute to avoid a boost spike (High Start PSI, low start duty). Alternatively, you can apply less air initally but apply it earlier to prevent boost spike (low Start PSI, High start duty). It may be desireable to do the latter to take the edge off a really hard hitting turbo.

Lower your gain to ~4 and hopefully you'll enjoy stable boost.

**** Lower the gain to ~4 and make sure your boost stays stable. If the gain is too high, boost can fluctuate. If it's too low, boost may creep up/down.

That's my take on the AVC-r / MAFTPRO boost control. Comments welcome....
 

turbobob

New Member
Aug 15, 2005
196
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0
Near Detroit
johnnyddn said:
I'm having trouble with Maft-Pro boost controller holding the PSI Set. Here are my current settings:

PSI Start - 11 psi
DC% Start - 50%
PSI Set - 14 psi
Gain - 10

The turbo will spool quickly to 14 psi but then once it hits it backs off quickly to about 7 psi. I've tried adjusting the duty cycle % up to about 65% down to 40% and noticed no real changes. I've also tried lowering the gain to ~4 to see if that would help. I'm just trying to get the controller set up so that it holds about 14psi at WOT and not spike all over the place.

make sure your solenoid is not installed backwards.....

B
 

johnnyddn

New Member
Jul 16, 2006
56
0
0
Las Vegas
I have the delco remy boost solenoid so it looks a little different, but I do have it attached the same way where the little filter is on the side that attaches to the turbo. But according to the instructions if I raise the DC% it should keep the boost near target PSI until it starts to boost spike. Well I've raised it up to as high as 85% and it still hasn't changed really. It seems that as if once the boost hits the targeted PSI (which I have to 14 psi) the solenoid just stays open and then lets the turbo's wastegate spring do its job which is why its boosting back down to 7 psi.

Trying to get a pic uploaded of what my solenoid looks like when imageshack starts working again.