The 7MGTE 89+ MAFT/MAFT PRO HAC MOD

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  1. #1
    CelicaSupra.com Member Daves2JZGTE's Avatar
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    The 7MGTE 89+ MAFT/MAFT PRO HAC MOD

    The 7MGTE 89+ MAFT/MAFT PRO HAC MOD

    If you don’t know what the maft or maft pro is go read hear
    http://www.fullthrottlespeed.com/

    I figured this out back in 2004 http://www.fullthrottletech.com/showthread.php?t=832 and since then only 3 people have asked me how to do it.LOL one of witch was the people that make the maft. I told them how to do it I just asked that they never charge for the mod and id like the credit for the mod well not the credit id like to be acknowledged for doing the hard part. Anyway thought it was time to do a HOW TO.

    First of the Y. The HAC censer is a censer that adjust the fuel/ecu for climate/altitude changes when driving. With the 1989 + 7MGTE ECU this censer is in the ECU. The 88- Is a external unit. When you swap over to the MAT / MAFT PRO the GM mass air censer that you use with the maft has the hac built into it. So if you don’t or cant tern off the hac censer in the ecu you will have a signal form the maft that is corrected for climate that your ecu will then correct again making it wrong.

    So that’s the Y now for the how.

    Open up your ecu and you will see this


    Now flip up the first board and you will see this


    What you are looking for is on my ecu marked D IS121 3L19


    If you look at it form the side you can see what the HAC censer looks like


    What you need to do is cut the trace that the hac single is on then replace the signal with that from the MAFT. Before we get to cutting lets look @ the back of the board


    Closer


    And better explanation if you connect the red wire to the yellow its just like stock. When using the Maft the red wire in this pic is just caped off and the yellow line runs to the maft. With my ecu i only ran one line out as seen in the first 2 pics but marked the other pin out for futcher reference.


    Now the cut part. The trace is in between the Hac D IS121 3L19 and D HE048 12KXX the part Number may be difrent in your ECU but the trace line is the same on all the ecus i have seen R505 !!! I just used a exact o blade to cut it.





    And that’s it.

    Now for my 2 cense on the MAFT….. If you can get a used one for CHEEP that’s cool. In a cense it’s a LEX 550 setup but better you can tune with it well sorta. With the first gen maft it has problems I E you cant get rid of “BC” With my car I have 580CC injectors and with the car running spot on with the maft I hit BC @ 17psi. BUT if I add about 10 psi to the base fuel presser then ree tune the car BC is up to 20/22 PSI. If you have not got injectors yet and would like to go MAFT or MAFT PRO id get 650 to 680 CC injectors instead of the 550 rout. If you plan to get a new MAFT get the GEN 2 it fixes just about all the gripes I have with the first gen maft. Now if I had the money id go MAFT PRO with the 680cc/650cc injectors (550cc is fine if you already have them you just may have to play with fuel presser to get what you wont) I say 680 do to the fact I run holly injectors a 65LB injector is = to about 680cc hens I have 55LB injectors now ~580cc. No holly injectors are not a drop in fit. You have to mod the fuel rail and get ford injector clips. The maft is like a lex and safc all in one the maft pro is that and much much more. If I ever step up to a real turbo I will get a PRO no Qs about it. Hope this helps someone.
    Last edited by Daves2JZGTE; 04-18-2008 at 08:20 PM.

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  3. #2
    CelicaSupra.com Member charles q's Avatar
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    Yeah, Dave, it helps quite a bit. I have been undecided about which route to go with the next phase of engine mods - AEM or MAFT PRO. There are obviously a lot of questions to answer before an answer can be achieved -pro or con. When making trade offs I always look at performance per dollar. Each set up has it's own advantages but I think on a performance per dollar basis MAFT PRO has the advantage. I'd like to see your set up one of these days since I'm so close.

    By the way in the SILV8DYNO 007 how much boost?
    C.Q.
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  4. #3
    CelicaSupra.com Member Daves2JZGTE's Avatar
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    Um SILV8 was 2004 that was the year i did 402hp if i remember correctly @ 16psi on 91 pumps gas

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    CelicaSupra.com Member Daves2JZGTE's Avatar
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    This is from Supramania. GrimJack was only the second person to ask about this mod. He did a how to also

    http://www.supramania.com/forums/showthread.php?t=32205

  7. #5
    CelicaSupra.com Member zank's Avatar
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    Thanks for posting this up Dave, whenever I get my POSpra running again Im probably gonna ask you to come over and help me set my MAFTPro too
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    CelicaSupra.com Member williamb82's Avatar
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    i never had any issues with my gen 1 maft, but i got 780cc/min injectors in there so maybe thats why. lol. good job on that fix though.
    william
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  9. #7
    is awesome kmfdmk's Avatar
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    double posted on acccident.
    Last edited by kmfdmk; 04-19-2008 at 08:24 AM.

  10. #8
    is awesome kmfdmk's Avatar
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    What exactly is the HAC? Just wondering as I'm building up a 7M-GTE and will be getting the MAFT-Pro kit in about a month. I'm going to be using the GM 3bar pressure sensor, so from what I read in your initial post the GM 3bar pressure sensor already has the HAC built into correct? (And if that's the case I wouldn't need to perform this mod??)

  11. #9
    CelicaSupra.com Member Daves2JZGTE's Avatar
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    Would you please read the first post agean

  12. #10
    is awesome kmfdmk's Avatar
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    Quote Originally Posted by Daves7MGTE View Post
    Would you please read the first post agean
    Gee Dave, I'm pretty sure I re-read the first post about three times to make sure I wasn't asking a dumb question. I realize through the broken engrish that the GM 3bar pressure sensor has a HAC built into it which corrects for altitude change, that corrected signal is sent to the ECU which then will make the change again; At that point the signal is incorrect as it has been adjusted twice.

    I still am curious what the #$%^ a HAC stands for. Forgive me for asking. I'll look it up elsewhere since you couldn't be bothered with typing "High Altitude Compensation."

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