MegaSquirt

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MegaSquirt is an aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of internal combustion engines. It is an open project headed by Bruce Bowling and Al Grippo, engineers that work on the U.S. East Coast. The project's do-it-yourself approach makes it the least-expensive system for this purpose. Basic costs can be below US$200 as of 2005, although this will vary widely depending on application.

1 History
2 Hardware
3 References
4 External links

[edit] History

MegaSquirt is a successor of sorts to Bowling and Grippo's earlier EFI332 design, which was more complex yet more powerful system (at least initially). The EFI332 project started around 1995, and culminated in the release of about 200 kits in 2000. The system used a 32-bit MC68332 microcontroller from Motorola, hence the name. A steep learning curve is believed to have prevented the system from gaining wider acceptance.

The two engineers decided to simplify the design and focus on managing the fuel injectors (the EFI332 could also control the spark plug ignition system if so desired). This was the basis for the first MegaSquirt.

[edit] Hardware

The assembled controller takes input from a few different sensors in order to manage the fuel injectors, including a throttle position sensor (TPS), exhaust gas oxygen sensor (EGO or O₂ sensor), MAP sensor, intake air temperature sensor (IAT), and a coolant temperature sensor (CLT). The latter two sensors themselves are usually the General Motors type, although you can recalibrate the controller to use other sensors.

As the project has gone through multiple hardware and firmware revisions, along with parallel projects that effectively "forked" the project and interlinked compatibilities, it is difficult to say with certainty which MegaSquirt is a specific version without knowing three things: microcontroller, printed circuit board and firmware versions.

[edit] Microcontroller

The version 1.0 MegaSquirt used an 8-bit Motorola MC68HC908 microcontroller, and all versions of the PCB support this processor. The later MegaSquirt-II upgrade includes a 16-bit MC9S12, and is considered an "intermediate" step from the original V1.01 and V2.2 MegaSquirt towards UltraMegaSquirt^[1]

[edit] Printed Circuit Board

The first group buy of printed circuit boards was performed in 2001. These boards are considered V1.01, and are no longer available. The second group buy in 2002, as well as all following purchases until 2005 are considered V2.2, and have a V2.2 printed in the upper left corner of the PCB. Starting in July 2005, the V3 PCB was made available to use some of the advanced features of the MegaSquirt-II.

[edit] Firmware

There are several related projects, including:

standard V3.000 code
MegaSquirt 'n Spark-Extra (MS-Extra)

MegaSquirt 'n Spark-Extra is a firmware modification to the original Bowling and Grippo MegaSquirt written by Philip Ringwood and James Murray. As the name implies it adds ignition management, as well as a large number of other features such as boost control, to MegaSquirt. Hardware modifications are required to run ignition and the learning curve is steeper than a fuel-only implementation, but many users report success with the "MSnS-E" firmware. The firmware is has been very actively developed and is now a stable alternative to the base MS code. The firmware is designed to operate using either a supported ignition system, such as GM HEI, or Ford's EDIS, or it can decode certain trigger wheel signals from crank/cam sensor pickups.