There are several ‘optional’ or ‘choice required’ steps during assembly of the PCBv3 MegaSquirt units, how are the DIYAutoTune ECU’s configured?

MegaSquirt-I EMS’s are setup by default as a fuel only EFI controller running though they are running the current stable release of the MS1/Extra firmware.  These are configured to be triggered from the (-) negative terminal of the coil by default.  It is fairly easy to convert them to be triggered from a Hall/Optical/Points trigger if you prefer.  Here are the steps to take:

  • Cut out C12 and C30.  Don’t jumper them or anything, just clip the leads and leave them out.  (Assembly steps 50h and 50d)
  • Jumper D1.  You can remove the diode first, but you don’t have to.  It’s easier to just solder a little lead shorting both of it’s legs together.

MegaSquirt-II EMS’s are by default configured for fuel and ignition control running the current stable release of the MS2/Extra firmware.  These are configured to be triggered from a Hall/Optical/Points trigger by default. 

MegaSquirt-III EMS’s are by default configured for fuel and ignition control running the current stable release of the MS3 firmware.  These are configured to be triggered from a Hall/Optical/Points crank trigger by default, and with the MS3X board added also support a similar Cam sensor input allowing sequential fuel injection.