Start here if you are new to MegaSquirt^® EFI Controller, this contains important background information.

• Frequently Asked Questions
• MegaSquirt^® EFI Features
• Principles of Tuning
• MegaSquirt^® EFI & Emissions
• The Development of the MegaSquirt^® EFI Controller
• What you NEED to Install a MegaSquirt^® EFI Controller
• Purchasing a MegaSquirt^® EFI Controller
• About this Manual
• MegaSquirt^® EFI Controller Forums
  • www.msefi.com, www.msextra.com, www.microsquirt.com, www.msruns.com, www.msgroups.com, www.ms3efi.com, www.msgpio.com.
  • B&G Forum Rules
• MegaSquirt^® EFI Controller Success Stories
• MegaSquirt^® EFI Controller Glossary

This section contains fundamental information on how the MegaSquirt^® EFI Controller works, and how it doesn't.

• The Ideal Gas Law
• Injectors
• REQ_FUEL
• MegaSquirt^® EFI Controller Fuel Equation
• Ignition Input
• Sequential Injection and MegaSquirt^® EFI Controllers

MegaSquirt-II™ Processor Upgrade

Here is information on the MegaSquirt-II upgrade daughter card.

• MegaSquirt-II™ Upgrade Introduction
• MS-II™ Hardware
• MS-II™ Embedded Code
  • Code Revision Details
• MS-II™ Processor Installation
  • Installing a second MAP sensor for barometric correction
• Configuring the MegaSquirt-II™ EFI Controller
• Tuning a MegaSquirt-II™ EFI Controller

  Principles of Tuning Get the Engine Started and Idling Cranking Pulse Widths Setting the PWM Criteria Resets Setting the Cold Start and Warm-Up Enrichments Tuning the Idle Control Tuning the VE Table(s)

  Tuning the AFR Table(s) Tuning the Spark Table Setting the Acceleration Enrichments Tuning for Economy Tuning and Emissions Tuning Issues

• MS-II™ Idle Air Control
• Spare Outputs
• Full-time Barometric Pressure Sensor
• Mass Air Flow Sensors
• MS-II™ Ignition Control

  Ignition Timing Tuning Distributor Pickups Alpha-Beta-Gamma Filtering Missing Tooth Wheels VR Sensor Noise/Resets Ignition Timing Algorithm Knock Timing Control GM HEI GM DIS

  Ford EDIS Ford TFI Bosch 0 227 100 124 MSD6a Toyota VAST (4AGE, etc.) Direct Coil Control Setting Dwell

• CAN and MegaSquirt-II™ EFI Controllers
• GPIO Hardware
  • MegaShift Code for the GPIO
• E85 (Ethanol) and the MegaSquirt-II™ EFI Controller
• Automatic Mixture Control
• X-Tau Enrichment
• Injector Test Mode
• MS-II™ Glossary

MicroSquirt™ EFI Controller

Here is information on the MicroSquirt^® fully assembled, reduced size ECU using MS-II.

• MicroSquirt^® Manual
  • Installation and Set-Up
  • Wiring
  • Driving Coils
    • Bosch 211 Module
    • LS1 Coils
    • LS2 Coils
    • Logic Level Drivers
  • MAF and MAF/MAP Blend
  • Dual Spark
  • Tooth Analyzer
  • Alpha-Beta-Gamma Filtering
  • MicroSquirt^® Code
• MicroSquirt^® Forums

MS-II Sequencer™ EFI Controller

Here are links to information regarding the MS-II Sequencer™ fully assembled ECU that can do sequential injection and individual cylinder fuel and spark trim.

• Introduction
• Schematics
• Coil Selection
  • LS1 Coils
  • LS2 Coils

This section contains the information on the V3 main board.

• Introduction to the V3 Main Board
• Assembly Guide for the V3 Main Board
  • Getting Questions Answered
  • Ordering Components from Digi-Key
  • V2 Stimulator Assembly & Instructions
  • V2.1 Stimulator Assembly & Instructions
  • Power Supply
  • Serial Communications
  • Clock Circuit
  • Input Section
  • Output Section
• V3 External Wiring Diagram
• V3 Troubleshooting
• Hall Input Circuit Modifications
• Adjusting the VR Pots
• Noise and MegaSquirt^® controllers

Information about the V3.57 SMD 'pre-built' MegaSquirt^® main board.

• Introduction
• Assembly Guide
• Hardware
• Ordering

This section contains the v2.2 main board assembly guide and troubleshooting information.

• Assembly Guide for Version V2.2
  • Power Supply
  • Serial Communications
  • Clock Circuit
  • Input Section
  • Output Section
• V2.2 Troubleshooting

Various MegaSquirt^® schematics and other info for troubleshooting.

• Connection Troubleshooting Guide
• Resets
• MegaSquirt^® V3 Main Board Information and Schematics
• MegaSquirt^® V3 External Wiring Diagram
• MegaSquirt^® V3 Main Board BOM
• V3 Troubleshooting
• MegaSquirt-II™ Daughter Card
• MegaSquirt^® V2.2 Main Board Schematics
• MegaSquirt^® V2.2 External Wiring Diagram
• MegaSquirt^® V2.2 Main Board BOM
• V2.2 Troubleshooting
• MegaSquirt^® Stimulator Assembly Instructions and Schematic
• MegaStim BOM
• Relay Board Assembly Instructions
• Relay Board Schematic
• Relay Board BOM
• MegaView™ Assembly Instructions and Troubleshooting
• MegaView™ Schematic
• MegaView™ BOM

This section has information on external wiring and sensors for use with the MegaSquirt^® EFI Controller. It is mostly for MS-I, for MS-II, also see the individual documents (above) for IAC, ignition, MAF, knock sensors, etc.

• External Wiring Schematic
• General Guidelines for Automotive Wiring
• Wire Sizes
• The Relay Board
  • MicroSquirt^® EFI Controller and the Relay Board
• Making a “PigTail” to Connect to a MegaSquirt^® EFI Controller
• MAP Sensor
  • 3 Bar GM MAP Sensor
  • Installing a baro MAP sensor for MS-II
• Oxygen Sensors
• Temperature Sensors
  • Sharing Sensors with the OEM ECU
• Easy Therm
• Throttle Position Sensor
• Fast Idle Solenoid
  • Stepper IAC
  • PWM Fidle
• Ignition Triggering
• Fixing Sensor Noise
• Sensor Troubleshooting

This section contains information on selecting and using air and fuel supply components for use with the MegaSquirt^® EFI Controller.

• Injector Selection
• Pulse Width Modulation
• The Flyback Board
• Injector Resistors
• Injector Bungs and Fuel Rails
• Throttle Bodies
• Fuel Supply System
• Fixing Low-Z Injector Noise

This section explains how to configure and tune MegaSquirt-I on your engine. For MS-II™, see the MS-II™ section.

• Principles of Tuning
• Tuning Theory
• Tuning Software
• Using MegaTune
• Resets
• Setting the Constants
• Before Starting Your Engine
• Get the Engine Started and Idling
• Setting the PWM Criteria
• Setting the Cold Start and Warm-Up Enrichments
• Setting the VE Table
• Tuning with Alpha-N
• Datalogging and MSTweak3000
• Setting the Acceleration Enrichments
• Check Certain Resistors
• Ignition Timing Tuning
• Setting Dwell
• Tuning Issues
• Tuning for Economy
• Tuning for Emissions
• Other Tuning Software and Platforms
• MegaView™
• Wireless Bluetooth and MegaSquirt^®

This section described the common features of Eric Fahlgren's tuning software MegaTune. It is the basis of the 'web help' (accessed by pressing F1 in MegaTune), so it may be worthwhile to make it available offline in your browser.

• MegaTune for MS-II 2.8 Code
  • Introduction
  • Installation
  • Resets
  • File
  • Fuel Set-Up
  • Ignition Set-Up
  • Basic Tables
  • Other Tables
  • Tuning
  • X-Tau Tuning
  • Other Tuning
  • Communications
  • Tools
  • Help

• MegaTune for Older B&G Code Versions
  • Introduction
  • Installation
  • Resets
  • File
  • Settings
  • Table
  • Tuning
  • Communications
  • Tools
  • Help

• V2.0 Downloader

TunerStudio MS is the MegaSquirt edition of TunerStudio by Phil Tobin, a next generation tuning application. It provides the ability to configure and tune all MegaSquirt controllers and is 100% compatible with MegaTune INI files and MSQ's.

• Main Site
• Download TunerStudio MS
• Download Java Runtime Environment (JRE) (needed for TS)

This section has links to various code files, software, and documents in PDF format.

• B&G Code
• MegaTune INI files
  B&G releases only
• PDF Documentation
  (may not be current)
• Software
  • MegaTune
  • Downloader
  • MSTweak3000
  • EasyTherm
  • USB Viewer Utility
  • Palm Edit
• MegaLogViewer
• MegaTunix
• VexME

This section is devoted to the specialized information needed when using MegaSquirt^® on a Wankel rotary engine.

• Throttle Body Issues
• Ignition
• Setting the Parameters in MegaTune
• Injector Specifications
• Mazda RX-7 Air and Coolant Temperature Sensors
• Kurt Staging

This section is provides information useful when using a MegaSquirt^® EFI Controller on a turbocharged or supercharged engine.

• Adding a Turbocharger to Your Engine
• Intercooling
• Water Injection
• Wastegates and Blow-Off Valves
• Plumbing Your Turbocharger
• Other Considerations
• Making a Turbo Exhaust Manifold
• MegaSquirt^® Hardware/Software Considerations
• Turbo Tuning with a MegaSquirt^® EFI Controller
• Setting the VE Table on a Turbocharged Engine

This section is for information on non-B&G hardware for MegaSquirt^®.

• Jean Belanger's Signal Interceptor Board
• Jean Belanger's dual VR conditioner board
• Jean Belanger's JimStim
• Jean Belanger's Peak&Hold Injector Driver Board
• Marc Piccioni's Expansion Board
• Willette Programmer for MS-I™

MegaSquirt^® Embedded Code

Here are guides to writing, compiling, and loading embedded code to MegaSquirt^®.

• MegaSquirt-I™ Code

  Code Versions Assembly Language Files Programming References Programming Software Why Assembly Language? Registers Addressing Memory

  Interrupts and Resets Serial Communications Ports Code Change Examples Some MegaSquirt® Variables Instruction Set MegaSquirt® 68HC908GP32 Memory Map

• MegaSquirt-II™ Code
  • Latest Code
  • Downloader
  • GCC Compiler
  • Serial Commands

• MSx/extra Code
  • MSx/extra FAQ
  • MSnS-E for MS-I
  • MS2/extra for MS-II

Miscellaneous MegaSquirt^® Information.

• MS-I™ Embedded Code Upgrade Instructions
• MS-II™ Embedded Code Upgrade Instructions
• MegaSquirt^® Glossary
• MegaSquirt^® 68HC908GP32 Memory Map
• Some MegaSquirt^® Assembly Language Variables
• MegaSquirt^® MC68HC908GP32 Instruction Set
• Programming a Blank MS-I Processor