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Megasquirt Modifications For Ignition Input.

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  • Megasquirt Modifications For Ignition Input.

    First of all...

    Many people including myself have worked hard to continually update the information on megasquirt and its features with the EXTRA code. This information can be found here:

    http://www.msextra.com/manuals/MS_Ex...nual_Index.htm

    PLEASE CHECK IT OUT!

    Also... I can not say this enough... http://www.msefi.com is an entire forum dedicated to megasquirt, megasquirt questions, megasquirt development, megasquirt related software etc. Most likely any questions you have can be directed and answered there.

    The link above is an updated link... I am continually amazed by the size of the megasquirt community and its continual evolution. My hat is off to a lot of people over there!
    Last edited by Ryanpzz; April 15, 2008, 05:59 AM.

  • #2
    Tach input For 1993 and 1994 Probe GT's

    Getting the tach input to work on a 1993 or 1994 Ford Probe GT is not terrifically involved.

    Hopefully by now you have read up and understand how to go through the megasquirt tuning software and understand terms like "msns" and ignition "trigger angle" If not, don't even bother reading this until you have!


    The disty on 1993/4 GT's has an internal crank position sensor that bounces from 5volts to 0volts (ground). Megasquirt needs a 12volt to 0volt signal in order to "sense" engine movement.

    In order to provide this, you will need to install what is called a "pullup resistor". I have tested and used a 680 ohm 1/2 watt resistor successfully for years without issue. This pullup resistor needs to be installed between a 12volt + power supply and the "tach input" pin on megasquirt. This can be done on the board itself, OR on the wiring harness going to megasquirt.



    In the picture the red line circles one leg of the 680ohm resistor as it is fitted in the board. If you copy the fitment of the resistor as shown in the picture you will have successfully installed your pullup resistor.

    Another thing I HIGHLY suggest, is installing a 4.7nf (nanofarad) capacitor. This is used for noise supression to prevent the tach line from reacting to the EM interference from surrounding electrical accessories.

    First you need to acquire a 4.7nF 35v capacitor like this one:

    http://www.mouser.com/index.cfm?hand..._pcodeid=58141

    The way this installs is very simple. The one end of the cap goes to a ground and the other end to the tach signal coming outta the hall sensor. I recommend installing this inside the MS box and not in the harness, but if you desire, it can be placed there as well.



    For installing it inside the MS box, you can see in the pic where it would go. The resistor you see on the end of where the cap would install is my pullup. Some of you may have your pullup as part of the wiring harness...this is fine, but make sure you use that hole by R29, NOT THE OTHER SIDE!




    When all of this is done, you should have a properly modified tach input circuit. If you wish to run the ignition portion you will also need to modify either the fast idle output OR the LED17 circuit to power either the stock or aftermarket ignitor.

    For the stock ignitor you need to use a 270ohm 1/2 watt pullup resistor to a 5 volt voltage source (left leg of R4 or R7 will do).

    For MSD or other ground triggered ignition system you can just run a wire from the Fast Idle output (pin 30) or from the (-) leg of LED17.

    ASSUMING you had a properly timed engine, a trigger angle of 60 degrees should get the engine to run appropriately WITHOUT modification to the disty.

    !!!!!PLEASE VERIFY THIS IS CORRECT WITH A TIMING LIGHT!!!!!

    Good Luck... Happy Modding
    Last edited by Ryanpzz; March 27, 2005, 08:01 PM.

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    • #3
      Sounds great. Just what I have been waiting for to connect the ignition part of MS.
      I want to use my stock ignition system in the disty to learn the ignition tuning.

      A drawing of the pullup resistor connection to use the stock ignitor would be appreciated very much.

      This saves some money on MSD, HEI, external coil , whatever else, for people willing to use the stock coil in the disty.

      The stock timing is supposed to be at 10 degrees.
      Last edited by turbo_KL; March 29, 2005, 05:15 AM.
      Registered since 2001, but now a new screen name says it all :-)

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      • #4
        Another question before using the spark output with the stock coil.
        How to set the dwell?
        Registered since 2001, but now a new screen name says it all :-)

        Comment


        • #5
          Originally posted by turbo_KL
          Another question before using the spark output with the stock coil.
          How to set the dwell?
          im running with the stock ignitor and coil. my settings:

          dwell control: fixed duty
          spark output duty cycle: 75%

          car started up on the first crank, idles smoother than stock
          Black 94 PGT - squirted, LSD'd, turbo DE/ZE hybrid @ 8psi

          Forget the dog...turbos are a man's best friend

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          • #6
            Is this feture onli for fuel setting?
            new record 11.20 a 120 !!!!!!!!!!!!!!

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            • #7
              Originally posted by turbo_KL
              Another question before using the spark output with the stock coil.
              How to set the dwell?
              The latest version of code

              024s9 is thus far working beautifully.

              It has a much more advanced version of dwell control. I use this set to 6ms starting dwell, 3.3ms running dwell, and .3ms minimum discharge.



              This is not only for fuel settings, this is only for the spark settings. to take advantage of BOTH fuel and spark control with megsaquirt.

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              • #8
                any pics of how to do this on the V3 board?
                Last edited by armyreserve100; November 27, 2005, 11:13 AM.

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                • #9
                  How and where to add a pullup resistor is included in the assembly instructions for the V3 board.
                  1994 PGT MS2 LC-1 370cc 190lph KLZE intake ported heads Turbonetics T4 2.5" Magnaflow STS MX3 flywheel ceramic clutch, 355fwhp ** sold
                  1980 Fairmont 4-door, S472, Megasquirt, 351C, 678rwhp.
                  2003 Mach 1, FR500 engine, 372rwhp w/out spray.
                  2003 Escape, slow.

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                  • #10
                    I know I know, this is an OLD ass topic, but it's exactly what I am going to do in 20 seconds... and the pictures Ryanpzz posted are no longer working, so anyone feel up to the task of posting pics or info of where the pullup needs to go exactly... thx

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