MegaSquirt was designed by Bruce Bowling and Al Grippo in 2001 and is a general purpose aftermarket electronic fuel injection system popular with DIY automotive enthusiasts. It is designed to use components reused from the existing vehicle or sourced donor vehicles This means that MegaSquirt EFI systems can use a much wider variety of components than the MegaJolt system.
Although MegaSquirt EFI controllers are engine management systems that can control both fuel and ignition, they may be used ONLY for ignition control if required. The most economical version of the MegaSquirt system is the MicroSquirt system. Similar to MegaJolt, the recommended location for the MicroSquirt controller is inside the vehicle cabin, away from direct engine temperatures because of its 185°F (85°C) maximum temperature limit.
While MegaSquirt systems also require technical expertise for installation and configuration, they are somewhat more of a bolt-on system than MegaJolt. While older electronic ignition systems rely on mechanical components (centrifugal weights & springs, vacuum pods) for the control of timing advance, MegaSquirt uses a later distributor with no centrifugal and vacuum advance. An earlier distributor with an electronic VR Sensor may be converted computerized use by locking out the centrifugal and vacuum advance. Alternatively, many later factory locked-out distributors may be directly bolted into the engine without modification.
However, the MicroSquirt Installation Manual does not recommend the use of a distributor for ignition:
Correctly modifying an old distributor to give a reliable tach input may well be more difficult than adding a crank trigger wheel and will never be as accurate. You are advised to consider installing a crank trigger wheel (e.g. 36-1) and sensor instead.
The code required to control fumigation fuel mixtures with a vacuum solenoid varying "atmospheric" pressure on the converter (ie, Dual Curve or Impco) or one or two stepper valves/motors (Technocarb or AEB) is different than what is require for fuel injection. If this code were written, the MicroSquirt controller would be ideal for fuel mixture and ignition timing control of LPG & CNG fumigation systems.