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PCB V3.57 and V3.0 HEI Input Mod Kit

PCB V3.57 and V3.0 HEI Input Mod Kit



SKU: MK-HEI Category:


This mod kit can be used with MS1 and MS2. It’s intended for the V3.57 boards, but can be used with the V3.0 as well; you just have to remove the XG1-XG2 and the TachSelect-OptoIn jumpers and replace them with the included header pins. The kit includes one normal green jumper, one red jumper with a 100 ohm inline resistor, and header pins. The V3.57 (DIYAT Rev A, all 3.57 ECUs built after 3/2009) boards already have all the header pins installed; the original version (sold prior to 3/2009) needs one header pin soldered to the 5 volt holes next to the processor. This mod kit allows easy installation of the MS1/Extra mods, and for MS2 it will give a stronger input signal than the regular mods in the MegaManual. As used on the DIYAutoTune Nova.

In summary:
MS1: This takes care of the input side of things, you’ll still need setup the ignition output on the ECU
MS2: This is all you need for HEI.  These boxes ship with the proper ignition output.

NOTE: You do need to trigger on the Falling Edge of the input signal when using this HEI modkit with your HEI ignition.  Make this change to your ignition settings in the tuning software.

See Part 2 of the Nova Carb-To-EFI article for a detailed ‘HOW-TO’ on using an HEI ignition system with a MegaSquirt-II! 

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Some directions use the VR circuit for input instead. What gives?

  • There are many workable options for HEI input with the MegaSquirt. This one gives a simple, no-adjustment, set and forget mod. There are other methods – just be sure to use all the settings and directions as a matched set to be sure everything works together.

Questions & Answers

    how do use this kit on a v3.0?
  1. 0 votes
    Q how do use this kit on a v3.0?
    Asked by Chauncey Hood


    • Remove the TachSelect to OptoIn jumper, and the XG1-XG2 jumper.  You won’t need them anymore while running HEI ignition.
    • The Red (resistor) wire runs from the #3 pin (OptoIn) to the 5v Pin near the MS2 Daughterboard.
    • The Green (no resistor) wire runs from the TachSelect pin (middle of JP1)  over to the XG1 pin.
    • Use the strip of pins to connect the wires to the individual holes on the board.


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