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Thread: Computer VM1

  1. #1

    Default Computer VM1

    Anyone have any idea what the green box on the end of this VM1 computer is?





    Nearing the end of the project, when I put on the Edelbrock intake and GT40P heads the computer started acting up and missing sporadically (once warmed up).



    I swapped in a DA1 computer I had laying around, and once it learned the tables it ran much better.










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  2. #2

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    That looks like a very old hypertech chip
    86GT-93LX-95GT

  3. #3

    Default

    Like Badsmurf said, it's for some sort of chip tune.
    It may have been custom.
    But, more likely, just some adjustments (like injector size, idle speed, etc).

    If you don't know what the chip changes, then chuck it. It will likely do more harm than good.

    The VM1 is for an '86 5-speed.
    The DA1 is for an '87/88 5-speed.
    The 87+ had the E7 heads, and an upper intake that was more tuned for max-hp (to look better in the specs and in the articles). The '86 upper intake is unique.


    https://www.corral.net/threads/vm1-e...cessor.633553/

    https://www.stangnet.com/mustang-for...cation.856536/

    Good luck.
    Last edited by stangPlus2Birds; 02-02-2020 at 05:50 PM.

  4. #4

    Default

    Thanks, good information there. I was familiar with the DA1 being one of the (relatively) better SD computers. Its bogging down a little from 2500 to 3k but really starts to pull above that, so looking at bolting on a mega squirt.


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  5. #5

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    VM1 was the most aggressive of the SD ECUs found in the 86-88 5-speed cars.

    Ford specifically released the VR1 and a few others like the DS1 in efforts to detune the 5.0L as warranty claims on T5ís started piling up.

    Generally you can swap a VM1 in the place of a lesser ECU like the VR1 or DS1 and immediately pick up a few 0.1ís ET and a few MPH too.

    Where people make a mistake is with thinking they will put in 14 or more degrees of base advance in like the A9L and others like and get away with it on a high swirl 86 head motor. You likely wonít get away with anything more than 13.5 ..... period.

    And there are diminishing returns. Usually you lose everything you gained in the prior 3-4 degrees for every 1/2 degree too far you go. Sometimes itís even worse.

    One of the other things about a VM1 is that it wonít pull timing based upon the VSS which greatly improves top speed in 5th.

    There is a specific reason there is a VM1 in both 1986 Saleen race cars

    But if you donít know what that chip is doing you may want to source another ECU. Iíd have to look at which one is in my pile of parts.

    VM1ís produce a notoriously lack luster idle characteristic if you take base timing past 12. They get to where they stumble and demand to be beaten about once every 30 minutes of driving ..... but letís face it who doesnít get after it at least every 30 min

    based upon the intake you are showing in pictures of you have free flowing exhaust and a good throttle body you are most likely running out of fuel up top. Pull a plug and take a look. My 86GT was dangerously lean before 6000. I had to increase fuel pressure which caused hard starts and a rather fat and pissed off idle. My answer was a swap to MAF which tolerated the added fuel pressure a little more. Still Iím going to switch to 24ís with stock pressure and either tune it or go to an X3Z ECU
    Last edited by erratic50; 02-09-2020 at 05:42 PM.

  6. #6

    Default

    Thats a lot of really good information, I had no idea that the VM1 was desireable.

    The motor is a 92 roller with GT40P heads and the Edelbrock intake, so its getting plenty of air and fuel.

    I probably need to get an MSD spark box, it bogged a little off idle to 2000 until I put a little more advance in the the timing - which resolved it.


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  7. #7

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    I wouldnít bother with an MSD unless itís required for a specific reason. The factory ignition works good well past the power levels the factory block supports

    Speed Density is usually not desired because people like to swap cams, etc..... but stock vs stock the VM1s would stomp most anything else and you could move the VM1 from one car to another and see the same behavior.

    They also do not contain the code changes to remove timing based upon speed which is why a stock Mustang with one will go so damn fast.

    With a mildly ported stock intake, a B302 (SD friendly) cam, 65MM throttle body, headers, and free flowing exhaust my car was on GPS at 163 in 4th at 5800 and went to 177 in 5th with a 0.68:1 OD before I backed out of it. The stupid car has been going faster before for sure too.

    You know youíre hauling when youíre well past 4200 in the high hole with a 2.73 rear gear.

    After the intake swap and a T5Z 0.63:1 OD Iím scared of the damn thing. Iíve bought to a 3.90 rear gear to swap in while getting it back to fix width out back. It will give it more kick and to slow it the hell down.

    only problem is that stupid ol 5.0 will pull past 6100 so I probably didnít accomplish all that much.

    the next motor will be a Dart 353 with a 7500 redline ..... it probably needs a crazy driver mod most of all. Lol
    Last edited by erratic50; 02-21-2020 at 10:24 PM.

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