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Megasquirt-3, MS3, MS3X

Manuals for Megasquirt-3 (MS3) ECUs (1.5.x firmware)

The manuals are split into three main sections : 1. Setting Up, 2. Hardware and 3. TunerStudio Reference. Manuals are available to download as PDFs or to view online page by page in your web-browser.

Note: 17 Jan 2017 – these manuals are in the process of being updated for 1.5.x firmware. Check back soon for updates.

1. Setting Up

This manual contains a QuickStart Guide, installation, tuning and feature background information.

  • Megasquirt-3 Setting Up manual PDF WWW

2. Hardware

These manuals contain wiring, fuel and ignition setup and board assembly details that are specific to your exact ECU version. Pick the ONE manual that applies to your ECU.

  • MS3base/V3.0 Hardware manual PDF WWW
  • MS3X/V3.0 Hardware manual PDF WWW
  • MS3base/V3.57 Hardware manual PDF WWW
  • MS3X/V3.57 Hardware manual PDF WWW
  • MS3 Gold Box Hardware manual PDF WWW (hardware versions < 1.2)
  • MS3 Gold Box Hardware manual PDF WWW (current 1.2 hardware)

3. TunerStudio Reference

This manual contains a reference of all the tuning settings, datalog fields and general TunerStudio usage.

  • Megasquirt-3 TunerStudio Reference manual PDF WWW

Archive manuals for firmware 1.4.x here.
Archive manuals for firmware 1.3.x here.

MS3-Pro manuals are available on’s site  or core manual: PDF WWW