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  1. #1
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    Default Convert from Speed density to MAF

    I have a 1986 Mustang GT with the 1st generation fuel injection on the 5.0
    If I want to do it for the least amount of money which way can I go to convert this to a MAF?

  2. #2
    FEP Super Member erratic50's Avatar
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    Multiport with manual or throttle body injected with auto?


    assuming 5-speed
    MAF meter from 87-93 LX or GT
    bracket from the same.
    intake tubes from the same or a cold air kit

    MAF plug robbed from a donor car in the junk yard. Get pins and a little wire to solder to from an EEC-IV ECU while you are there.

    4 colors of wire. Wire loom. Shrink tubes. Solder pencil. Electrical tape.

    A9L ECU. Several others work, that one performs most aggressively of the MAF computers.
    A9P if you run an automatic

    i have a doc I built when I converted mine.

  3. #3
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    Quote Originally Posted by erratic50 View Post
    Multiport with manual or throttle body injected with auto?


    assuming 5-speed
    MAF meter from 87-93 LX or GT
    bracket from the same.
    intake tubes from the same or a cold air kit

    MAF plug robbed from a donor car in the junk yard. Get pins and a little wire to solder to from an EEC-IV ECU while you are there.

    4 colors of wire. Wire loom. Shrink tubes. Solder pencil. Electrical tape.

    A9L ECU. Several others work, that one performs most aggressively of the MAF computers.
    A9P if you run an automatic

    i have a doc I built when I converted mine.
    Cool, I'd like that. Hard to find mustangs of that era here in the salvage yards

  4. #4
    FEP Super Member erratic50's Avatar
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    Pm me your email address, I'll send it to you.

  5. #5
    FEP Power Member Broncojunkie's Avatar
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    Why convert to maf? The only reason I can think of is because sd can't handle certain performance mods (cams, bigger injectors for instance). At that power level, the stock maf stuff isn't going to accommodate much. Used a9p/a9l ecm's are running $200+. Bigger throttle body and aftermarket maf, another $200. Intake will cost between $100 and $700, depending on used vs new, aftermarket vs stock. I was into mine for nearly a grand (explorer intake, 24lb injectors, new tb and spacer, used ecm, etc). For $800 and a cheap used carb intake, I could have had a much better stand-alone efi system.

  6. #6
    FEP Super Member erratic50's Avatar
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    With stock style E6 or E7 heads 19lb injectors are good enough. Good to around 320HP at max duty cycle

    Procom/Typhoon EFI - $250
    MAF $100
    MAF ECU $100-150
    Explorer 65MM $25, requires conversion per tom moss
    egr spacer. Port the stock one or buy used $50

    Honestly I have almost as much money in my Edelbrock carb and air gap for my 85.

    My setup's problem is with a Cobra 70MM my motor goes lean at high RPM. The injectors are about maxed out. I added fuel pressure and it pulls past 6100 but it's a bit rich at idle.

    The air flow readings are different on the 70 than on a GT's 58. I bought a Cobra ECU and 24's for my EFI setup a while ago as my plan to get it running right before a rebuild. Lazy approach..... I have a moats quarterhorse and binary editor and logging software if I ever get around to messing with it.


    Now for the SD vs MAF side of the discussion.

    If you want a decent cam - there is no discussion if staying with stock style systems. Some of the aftermarket ECUs are SD and do well with upgraded cams.

    Ignoring the aftermarket stuff....

    The 5.0L HO cars with MAF idle better.

    They make more low end and midrange torque.

    Many SD tunes like the VR1 and DS1 aren't as aggressive as the A9L MAF computer. VM1, it's debatable.

    My 86 had a VM1 and was marginally quicker in the 1/4 running SD.

    Every drivabilty issue I ever had with SD and my car turned up transplanted into my son's 86 when we put the VM1 in. And it runs a whole lot like mine always did. Total sleeper

    I'd do the swap to MAF again because I find my car more fun to drive when I'm not beating the hell out of it. The SD setup just begged for constant WOT.

  7. #7
    FEP Power Member Broncojunkie's Avatar
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    I rarely see used ecm's these days for under $200. I literally just sold one a few weeks ago for $250. The bad part is, these ecm's are approaching 30 yrs old and they're problematic. A buddy just went through 2 of them in the last year. That's about $300 worth of parts, and he eventually sent one of them out for a $200 rebuild. That's $500 or more just in the a9p/a9l.

    I just can't see how saving a couple hundred bucks (very best scenario) by going with the stock maf setup beats an $800 stand alone. As a matter of fact, I'm seriously thinking about stripping mine off, selling everything, and installing a fitech or holley efi.

  8. #8
    FEP Power Member Ourobos's Avatar
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    Did my 86 SSP a few months back..

    4-pin MAF plug
    extra pins for the 60 pin connector at the ECU harness
    4 runs of wire and some loom
    stock MAF meter (no need to swap injectors or intake - not sure why that was discussed above?)
    Proper MAF tubing to your airbox if still stock
    Mass air ECU
    My car was a non-cruise, and lacked a VSS sensor, I added that and it's wiring as well.

    My car idles and runs better than it ever had, and it's pretty stock, and now gets 20 mpg..

    Best write up is here :

    https://www.stangnet.com/2002/01/23/...ir-conversion/
    1986 CHP SSP Coupe

  9. #9
    FEP Power Member Broncojunkie's Avatar
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    Quote Originally Posted by Ourobos View Post
    (no need to swap injectors or intake - not sure why that was discussed above?)
    I explained why in a post further up, I believe. You technically don't have to change the intake. However, most people don't do a maf conversion because of their poor idle (my speed density seemed to idle fine). They do it because maf supports performance upgrades. The oem setup (intake included) doesn't support the power levels most people are looking for.

  10. #10
    FEP Power Member Ourobos's Avatar
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    I agree the intake is the bottle neck of the 5.0.. That being said, I put an explorer intake on my 86 when I changed it to mass air.
    1986 CHP SSP Coupe

  11. #11
    FEP Power Member Broncojunkie's Avatar
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    Quote Originally Posted by Ourobos View Post
    I agree the intake is the bottle neck of the 5.0.. That being said, I put an explorer intake on my 86 when I changed it to mass air.
    That's what I'm running on my 88gt. I was really impressed by the power that car makes. I had a b303 cam lying around, so I used it....regretted it after the motor was in, so I got 1.7 rocker arms. 24lb injectors/maf, cai, and new throttle body and spacer. I don't know if an aftermarket intake would help or not, but it's already fast enough to scare the wife. It's her car and she doesn't like driving it lol. I think it's a blast.

  12. #12
    FEP Super Member erratic50's Avatar
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    Aftermarket intakes increase performance hugely vs stock. this is true even on a "crappy" E6 head HO motor. Stock intakes only flow 110 CFM front and rear cyl and 130 on the other 6. This vs 155-160 fellow potential for stock heads. No wonder the stock motors fall on their face at 5000.

    Explorer intakes flow past 150 but require porting to get anywhere near an aftermarket head like an AFR. The other problem is runner length vs plenum. They are all done by 5800, no way around it. Shorter cobra intakes and GT40 are good to 6500 or so as they are 2" shorter in the runners.

    The stock ECU was fine with the intake swap alone. I even have a late 80's speed density friendly slight cam upgrade in my car. That's not a MAF vs SD problem until a more serious cam is added, then having nobody who knows how to tune a SD ECU makes it the problem.

    I mentioned 24lb injectors and a Cobra ECU above because with just moderate upgrades you're running out of fuel system capacity. 200-225 net HP is not that far from 300 crank HP. And 19's are max duty at 320 unless you jack up fuel pressure.

    What to expect .....

    I had headers and 65MM throttle body when I swapped to a Typhoon EFI setup rated for 1500-6500. It is now slightly down on torque from idle to 1600 but rapidly makes up for it as R's increase. Adds around 40-50 peak torque and HP and raises the peak RPM for each. MAF brought some lot of the lost low end torque back.

    my motor bogs a little easier off the line than before the intake swap which I learned the hard way while messing around with my son in his 86 when he pulled 2 lengths on me coming out of the hole..... lol. Launch RPM increased now accordingly.

    Mine does rocket away from my son's stock (but turned up and running the aggressive VM1 ECU) 86 by a big margin in the upper RPM ranges.

    4500-6100+ is party time and no doubt the intake makes a car that knows how to have a good time. I'd go farther than 6100 but I try not to bounce off the rev limiter while running full power shifts with it....

    The add power is great. I ran 2nd to 85 while he shifted at ~70. I made up for the lost ground and absolutely flew past him.... then I missed 3rd. Game over. Lol. My 1352-169 to T5Z conversion build has a shifter pattern problem that I need to solve.....

    On road courses the stock motors often have too much grunt and blow the tires off coming out of corners. The right intake fixes that problem. The power is there but more mild mannered in delivery and easier to control which has its advantages.

    Mine still has 2.73's. Now it has a 2.95 low also. Even still before the intake swap while going 25 down the street in 1st if I stood on it the the car would simply blow the tires off. Immediate tire smoke. Now when the same thing is done there is still slight slippage but not enough to fry the tires and blow them off. It gets up and goes. And the 25-60 pulls in 1st are an absolute blast....

    thats more or less what to expect, cam selection being a big variable still.
    Last edited by erratic50; 01-21-2018 at 02:38 PM.

  13. #13
    FEP Power Member Broncojunkie's Avatar
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    The wife's 88gt does as you described...You can be moving along in 1st, step on it, and just blow the tires off. Heck, it tries to do it in 2nd lol! I could partially blame the 3.73 gears for that. It does run out of steam fairly quickly. It's a fun car to drive, but needs to be better matched if I ever decide to take it to the track.

  14. #14
    FEP Super Member erratic50's Avatar
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    You have quite a bit more gear in back. I'm running 0-60 entirely in 1st gear but still had enough steam to blow the tires off going 25-30 down the street in low with the stock intake. Same procedure at 25-30 with the typhoon it digs in and goes. if I speed up to 35-40 before I stand on it I go immediately to spinning before the weight transfers but it hooks up once it transfers and does not enialate them. And now instead of being done at 45 I'm pulling harder than ever 45-57 (or if doing 0-60-0 pulls I leave it in 1st) and the shift to 2nd is right in the power band and pulls to 87-88. I usually look for 3rd around 85-86 so I don't hit the rev limiter at 89-90.

    My car definately needs some rear gears. I'm thinking 3.90's or 4.11's when I rebuild my 8.8.

  15. #15

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    erratic50, any chance of getting that doc too? I have an '86 Lincoln Mark 7 that I'd like to convert to MAF as well - compass8000@telus.net...thanks a lot!

  16. #16
    FEP Super Member erratic50's Avatar
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    I will dig it up and send soon. If I forget pm me here.

  17. #17

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    I'm interested to hear your guys opinions on these discrepancies. I have an 86 thunderbird I have been wanting to convert. I have 14lbs injectors which I'd need to upgrade. I have flat top pistons as well which severely limits my head choices. My question is, is it safe to convert to MAF on a non HO engine? I heard that I would need to swap my cam and heads for it to work. Any input appreciated. The engine will be eventually rebuilt with 87 internals in which case I will do the swap then anyway but I'd like to do it now.

    Sent from my SM-G920V using Tapatalk

  18. #18
    FEP Super Member erratic50's Avatar
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    Injector firing order is in direct correlation to spark plug firing order. It's possible to move pins around on the wiring harness so the correct injector fires vs firing order, but the O2 sensors may or may not be on the correct side-- review the firing orders. If that is a problem you might Y pipe it and put them side by side.

    Anyway -- easier to leave it alone until the time comes to cam swap it.

    jump up to an X3Z ECU and 24's with a 70MM cobra MAF.

  19. #19

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    Hey I have a 1986 gt harness complete with msd 6al2 box that has rev limiter and 2 step built in and mass air a9m computer which is a convertible a9l mass air computer all complete in a box that I was going to use on my car. It ran absolutely perfect with b-303 cam. I even have the upper and lower intake with bigger throttle body and the pro-m mass air meter that were all working together. Make me an offer. - Sam

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