by Bowling and Grippo

The MegaSquirt® Family of EFI Controllers

The MegaSquirt® family of programmable electronic fuel injection controllers are standalone EFI controllers that offer very flexible tuning options using a laptop computer. These controller range from build-it-yourself controllers to completely assembled, ready to install controllers. Some MegaSquirt® vendors even offer ready to install wiring kits complete with finished wiring harnesses and tuning for certain vehicles.

However, the MegaSquirt® family of EFI Controllers is not designed to be a 'no hassle' solution to user's EFI needs. Instead it is intended to be an educational process. As a result, a large amount of reading and study is required. If you are new to the MegaSquirt® community, you may find there is a lot of new information to digest, and much of it will seem confusing, or even contradictory. Your best bet is to read and re-read the FAQ and the manual thoroughly.

The MegaSquirt® FAQ is here: Frequently Asked Questions, and the manual is here: MegaManual™ Table of Contents. These sites are primarily for those wanting to learn the theory, implementation and tuning of electronic fuel injection systems for internal combustion engines. If you prefer to see if a MegaSquirt® EFI controller might work on your specific vehicle before proceeding, you can:

• Check the DIY Autotune site,
• Check the MegaSquirt® Success forums, or
• Use Google to search for other references.

There are a large number of considerations, build options, and independent hardware configurations that may suit you and your vehicle, but only you know your wants, needs, and abilities. As well, any of the family of MegaSquirt® EFI controller are 'universal' ECUs, and it is up to the user to sort out the details for their vehicle. Others may be able to provide some help on your vehicle, try the forums at www.msefi.com for general MegaSquirt® information and support, or look on the DIY Autotune site. Some other vendors also have application specific guides (see the vendors listings).

The MegaSquirt® family of EFI controllers includes:

• MS-I™,
• MS-II™,
• MicroSquirt™,
• MS GPIO CAN Expansion Board, and
• MS-II Sequencer™.

Note that any MegaSquirt® EFI controller is the controller only, you will have to gather the remaining fuel system parts yourself (from 1 to 16 injectors, sensors, fuel rails, fuel pump, etc.). Several vendors offer these components, sometimes bundled with a MegaSquirt® EFI controller.

MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes. MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the applicable laws in your locality to determine if using MegaSquirt is legal for your application. For more information, see: www.megamanual.com/tamp.htm

Experimental means that YOU are responsible for sorting out some details of your fuel injection that are specific to your application. Do-it-yourself means that you save money by assembling it yourself with a few basic tools and comprehensive instructions.

A MegaSquirt® EFI Controller will provide fuel control on one to 16 or more injectors, of high or low impedance, and for any number of cylinders, even three and five cylinder engines and odd-fire engines. If you have MegaSquirt-II, electronic control of number of ignition systems are supported, including: 7 or 8-pin HEI from General Motors, EDIS from Ford, TFI from Ford, or you can control a single coil directly. For fuel only control, you can trigger off the coil's negative terminal.

There are four main aspects to the MegaSquirt® EFI Controller system:

1. Processor: You can select one of two processors (68HC908 or MegaSquirt-II). MegaSquirt-II has a faster processor, better injection pulse resolution, and has a number of added functions (like a ignition control, stepper IAC driver, and user configurable spare outputs for things like fan control or shift lights).

   The 8MHz 68HC908 processor, used for MegaSquirt-I™, is a small black integrated circuit (chip) about 0.6" x 2.0".

   MegaSquirt-II™ processor upgrade (aka. MS-II™ or MS2, also used in MicroSquirt™ and MS-II Sequencer™ controllers) is a small (1.15" x 2.6") assembled PCB (printed circuit board) that plugs into the same 40-pin socket on the main board as the 8MHz 68HC908 processor, but uses the much more powerful 24MHz MC9S12C64 processor with 128K of memory.

   MegaSquirt-II: (MC9S12C64)	MegaSquirt-I: (68HC908)

   MS-II Sequencer™ uses two parallel MC9S12C64 microprocessors to provide sequential injection and coil on plug control for up to 8 cylinders.

   There is also a 'smart' I/O CAN-enabled expander board (for MS-II and up) with an on-board MC9S12C64 processor, called the GPIO board.

2. MegaSquirt® main board or printed circuit board (PCB): This can be based on one of four PCBs (V1.01/V2.2/V3, or V3.57). The V1.01/V2.2/V3 PCBs are similar, and all are 6.00" by 4.00" (~152.4mm x 101.6mm) but later versions have some added features that make some installations more convenient.
   

   The V3.57 board is mostly surface mount devices (SMD), and it is not a DIY board, but it is the same size (6.00" x 4.00") and fits in the same case. There are also the smaller MicroSquirt®, MicroSquirt® Module, and MS-II Sequencer™ boards. Each of these is machine assembled with all of the required components.

3. Embedded code (aka. 'firmware' or 'code'): this is loaded onto and stored on the MegaSquirt. It must match the processor you are using. There are sometimes several options for a particular processor, for example to the standard code for the 68HC908 processor. The MS-II code can be found here. You can also check the MSx/extra code. All of the codes are free to download to upgrade older MegaSquirts.

4. Tuning software: TunerStudioMS, MegaTune, etc., can be used. These run on a laptop or notebook computer, and lets the user see, adjust, and record ("datalog") the tuning parameters by 'talking' with MegaSquirt® through the serial port (the laptop has a serial port, and MegaSquirt® does too. A DB9 cable connects them. This part of the system, the tuning software is where you do most of your 'interaction' with MegaSquirt. The tuning software has been designed to work with any of the code/processor combinations, but you may have to configure it. Click the links above to get the latest version.

There are also a number of optional components to the system:

Here are a few general questions to ask yourself before digging into the documentation to see the specific functions of each main board and processor/code combination:

a. Will you built it yourself?

• If NO, then you will likely want a 3.57 main board with either an MS-I™ or MS-II® (see below) processor, or MicroSquirt®/MS-II Sequencer™.
• If YES, you are building MegaSquirt® yourself, you have the option of V2.2 or V3 main boards. V2.2 is slightly cheaper, but the V3 main board has many more options, improved circuits, and more extensive documentation.

We recommend V3 in all cases for those wanting to assemble their own board.

b. Will you be controlling ignition timing?

• If NO, then MegaSquirt-I™ will most likely suffice.
• If YES, then an MS-II® or MicroSquirt® (or MS-II Sequencer®) is your best option for controlling spark advance.

c. Is there anything you'll need to control besides fuel and ignition?

If you have a stepper motor or PWM idle control valve you will need an MS-II® (or MS-II Sequencer™) to control this. On/Off idle valves can be controlled with MS-I™.

MS-II® and MicroSquirt® controllers also have user configurable outputs called 'spare ports' to control other functions (fans, shift lights, etc.). You should check the documentation carefully to see if your devices can be controlled successfully with the hardware and code you choose.

If you have an electronically controlled automatic transmissions, you may be able to use the GPIO board from Bowling and Grippo along with the MShift™ transmission code to control it.

d. What size injectors will you be running?

If you are running large injectors for your displacement (typical of high output engines - turbocharged engines, race engines, etc.), you will likely need MS-II®, MicroSquirt®, or MS-II Sequencer™, as these have 100 times better pulse width resolution than MS-I™, which really helps when trying to set the idle and cruise pulse widths.

Though most engines will not benefit enormously from sequential injection, those desiring it can use the Sequencer for up to 8 cylinders.

To find out more about MegaSquirt® EFI Controllers, read this page first, then the Frequently Asked Questions, then read the manual by following the link to the table of contents. These should answer most of your questions. For even more info, or to ask questions, register with one or more of the MegaSquirt® forums (you have to register with each forum separately, but you can use the same username - if available - and password for all of them).

MegaSquirt® EFI controllers are for experimental and educational purposes. No warranties are expressed or implied. Neither Al Grippo nor Bruce Bowling are responsible for the construction, installation, or targeted use of this unit. This unit has been tested on many engines, however, it is an experimental unit and the end-user assumes all responsibilities for its use and application. Do not use in an aircraft which, if the unit fails or ceases to operate properly, can fall out of the sky. Do not use on a boat where, if there is a failure, results in a situation where the vessel is stuck in a hurricane and sinks to the bottom of the ocean. In other words, follow the manual carefully, and seek authoritative help if you have questions.