Hardware Features

I am using a DIYAutune MS3x standalone engine computer. There are several generations and iterations of the Megasquirt hardware. It would impossible to cover all versions and options in this wiki, so we will cover the MS3x only.

You can read about the many versions and options here.

Megasquirt-3 is the top of the range ECU in the ‘traditional’ Megasquirt range. It has 8 fuel and 8 logic spark outputs offering full sequential fuel and spark for hi-z injectors and logic level coil-on-plug coils (or high-current coils with suitable external ignition module.) This supports full-sequential on a V8 or semi-sequential with wasted spark on a V12. Spark and fuel are fully trim-able per channel and injector timing is mappable for optimum power (~1% gain available) Six relay or solenoid outputs for nitrous, boost, fan control, shift light, tachometer outputs etc. Switch inputs for launch, idle-up, nitrous-in etc. and additional sensor inputs for external MAP sensors or measuring pre/post intercooler etc. On-board SD-card datalogging allows fast datalogging without the need for a laptop while logging. Built-in USB-serial adapter eases connection to modern laptops.

CAN communication ability to interface with extender boards for more inputs and outputs on the more complex installs – e.g. multiple EGT, multiple widebands, speed sensors etc. Calibration to adapt to OEM temperature sensors is straightforward and numerous wideband calibrations are supported.

Initial setup is aided by test modes for the fuel and spark and by built-in tooth loggers to help diagnose incoming tach signals.

In most configurations, the MS3 + MS3X +V357 can be used by setting a few configuration jumpers inside the box. It requires less customisation than other traditional Megasquirt options which are far more DIY intensive.

The Megasquirt-3 (MS3) is ready to support a wide variety of engines out of the box, with the ability to control anything with one to eight cylinders with sequential fuel injection and sequential ‘coil on plug’ ignition, a V12 with semi-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, Ford Zetec, Bosch Motronic, and Chrysler Gen III Hemis to unusual modes like Renix Jeeps and the Suzuki Swift GTI. The software includes many ‘race’ type features, two stages of progressive nitrous, water injection, closed loop boost control etc. Vehicle speed sensing, logging of EGT (with external hardware.)

The case measures:
Length (end plate to end plate, not including flange): 161 mm
Length (end plate to end plate, including flanges): 182 mm
Width: 105 mm


Megasquirt-3 Hardware features

  • Freescale MC9S12X 16 bit, 50 MHz asymmetrical dual core processor
  • 8 saturated injector drivers
  • 8 logic level ignition outputs
  • 5 medium current (3 amp) general purpose outputs
  • All unused injector and ignition outputs can be used as spare on/off or other outputs.
  • 1 stepper H-bridge driver
  • Camshaft and crankshaft 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
  • 1 spare digital frequency inputs
  • RS232, USB 2.0, and CAN communication
  • Onboard SD card slot for internal data logging
  • Temperature range: -40 to +85 degrees C
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