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MS3-Pro: MegaSquirt like you've never seen it before!


The MS3-Pro is the top of the MegaSquirt line. This new system is based on the proven MegaSquirt-III design, with a number of revisions made by DIYAutoTune in order to completely meet the needs of professional tuners and racers.

Now Available!  Click here to order!

Click here to download complete MS3-Pro documentation.

Download MS3-Pro wiring diagrams / pinouts only

We're also developing supplimental MS3-Pro installation guides that include wiring diagrams, settings notes, and other advice:

The MS3-Pro combines the features of the MegaSquirt-3 with all available 'expansions' built right into a single circuit board in a sealed case. The o-ringed case is splashproof and, if you want continuous immersion resistance (the MS3-Pro displayed at PRI was at the bottom of a fish tank), it's easy to add a bead of silicone for extra protection.  Furthermore, we've updated the power supply design to use a switching power supply to minimize energy consumption and maximize stability of operation. The MS3-Pro will remain powered up even if battery voltage drops as low as 6 volts!  We also included the new intelligent knock sensor capability, allowing for advanced knock windowing and noise threshold configuration, integrated internal SDCard datalogging with time stamping of all datalogs, USB and RS232 Serial tuning interfaces, individual cylinder tuning for fuel AND ignition timing to allow you to compensate for differentiation in flow characteristics to different cylinders and truly maximize engine output, and more!

The MS3-Pro is ready to support a wide variety of engines out of the box, with the ability to anything with one to eight cylinders with sequential fuel injection and sequential 'coil on plug' ignition, a V12 with sequential fuel and wasted spark ignition, or a four rotor Wankel with separate leading and trailing ignition outputs. Over 50 different ignition modes are supported, from mainstream applications like the GM LS1, Bosch Motronic, and Chrysler Gen III Hemis to unusual modes like Renix Jeeps and the Suzuki Swift GTI. 

The MS3-Pro's packaging is also a departure from most previous MegaSquirt EFI Systems. Instead of the industrial looking split aluminum case and D-sub connectors, the MS3-Pro uses a sealed high temperature nylon case for light weight and compact size, and heavy duty AMPSEAL connectors. This provides a compact and sealed enclosure protecting the sensitive internals from the elements. The MS3-Pro's design keeps the heat generated to a minimum, allowing it to use a lighter plastic case instead of a metal heat sink.


  • Length: 150 mm edge to edge, 180 mm ear to ear
  • Width: 100 mm
  • Height: 28 mm to top of case, 43 mm to top of connectors with harness not installed
  • Weight: 260 grams

Retail pricing for both the ECU and wiring harness is under $1,200 and it's now available here!

MS3 Pro goes swimming at PRI 2012!

MS3 Pro Gone Swimming.... while running a full fuel/ignition system!


Take a look at this video of our PRI 2012 (Performance Racing Industry Tradeshow) booth including a demo with the MS3 Pro sunken into a fishtank while actively controlling a test bench with full fuel/ignition system spraying fuel and sparks!  

Walk-thru of's 2012 PRI Booth - MegaSquirt-3 PRO (aka MS3 Pro)


Here is a complete list of the MS3-Pro's features:

Hardware features:

  • Freescale MC9S12X 16 bit, 50 MHz asymmetrical dual core processor
  • 10 saturated injector drivers
  • 8 logic level ignition outputs
  • 3 high current (5 amp) general purpose outputs - 2 can be reconfigured as additional injector drivers, and all can be used as PWM outputs
  • 3 medium current (3 amp), high frequency general purpose outputs
  • All unused injector and ignition outputs can be used as spare on/off or other outputs.  This ECU has a LOT of I/O!
  • 1 stepper H-bridge driver
  • Camshaft and crankshaft differential inputs - supports VR, Hall effect, and optical input
  • 12 volt tach output
  • Fuel pump output
  • 8 analog inputs (5 dedicated sensor inputs, 3 spare/general purpose)
  • 4 spare digital on/off inputs
  • 3 spare digital frequency inputs
  • 2 knock sensor inputs
  • RS232, USB 2.0, and CAN communication
  • Onboard 8 gigabyte SD card for internal data logging
  • Internal ECU temperature sensor
  • Real time clock
  • Temperature range: -30 to +80 degrees C (-40 to +85 without battery for real time clock)

Software features:

  • Supports speed density, alpha-N (TPS based), or MAF based fuel and spark tables
  • 1 microsecond injector pulse width resolution
  • Tables for nonlinear injector behavior at small pulse widths
  • Allows blending multiple load types, including specialized mode for independent throttle bodies
  • Supports a wide variety of OEM cam and crank position sensors
  • Individual cylinder trim tables for fuel and ignition
  • Accelerator pump or model based acceleration enrichment
  • Closed or open loop idle speed control
  • Closed or open loop boost control with two separate wastegate outputs, and gear or speed based tuning options
  • On/off or closed loop continuously variable valve timing (VVT) control - supports up to 4 channels
  • On/off or progressive nitrous control
  • Traction control by VSS or RPM
  • Rally anti-lag with rotational idle
  • Rotary support - can run up to 4 rotor engines with separate leading and trailing spark tables
  • Staged injection
  • Table switching
  • 16 x 16 fuel and spark tables - can be reconfigured to function as 30 x 16 or 16 x 30 by switching tables based on RPM or load
  • 2 or 3 step rev limiter (launch control) with no-lift shifting
  • Wideband AFR target tables
  • Flex fuel sensor input for easy switching between gasoline and E85 - can automatically change fuel, ignition, and boost maps based on ethanol content of gasoline
  • Knock control with adjustable crank angle windowing can adjust sensitivity based on RPM or which cylinder is firing
  • Allows repurposing injector or ignition outputs as general purpose outputs, or high current outputs as injector drivers for 12 cylinder sequential applications
  • Real time barometric correction (external sensor required)
  • A/C and cooling fan control with idle compensation
  • Safety shutdown based on AFR or EGT input
  • Sequential shift cut and air shifter control
  • Diagnostics to detect and ignore failing sensors - can even automatically switch from speed density to alpha-N in the event of a MAP sensor failure

Although the current MS3-Pro is a universal, wire-in ECU, expects to follow up with several plug and play variations for 2013.   First up: C4 ZR-1 Corvettes!  Next?   MKIV Supra Twin Turbos!




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