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[Datsun 1200 encyclopedia]


From Datsun 1200 Club

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Categories: Engine Modifications | Fuel Injection

MegaSquirt/MicroSquirt is a low-cost electronic engine controller that several club members are using to control their A-series engines. It can control Fuel Injection and ignition (spark) both, or either by itself. MicroSquirt v3 is a version of MegaSquirt 2 in a smaller, pre-built package. The only problem is finding the exact information on how-to (there is waaaay too much information on the various MegaSquirt/MicroSquirt variations).


See Also

For general info, see: wikipedia:Megasquirt
For Frequently asked questions, see 
* MegaManual
* DIYautoTune
MegaSquirt can run you ignition system even on non-EFI engines. However, if you only need spark-control (fully programmable ignition curves) the MegaJolt-EDIS product is less expensive and simpler to install.


MegaSquirt is used on the most pedestrian of stock engines, to all-out racing cars. Megasquirt can do anything more expensive ECUs will do. There is more DIY to it though. That's the down side, version numbers -- and therefore documentation -- are vastly confusing. On the plus side it doesn't need expensive dyno tuning. Instead you can use charts to adjust for Datsun sensors/injectors and use a standard tune that will work quite well. For fine tuning you can use a wideband O2 sensor or pay someone to do dyno tuning.

Both do everything
MeqaSquirt  $    poor docs, DIY support
Other ECU   $$$  phone support available

You will find documentation saying MegaSquirt can't do a certain thing, while in reality a more current version can do it (and sometimes older versions with software updates). Because it's DIY, it is not always clear what version a user is talking about. There is no one-set-of-documentation.

All MegaSquirt use the same circuit board design. The difference is the processor plug-in. MegaSquirt I is 8-bit, MegaSquirt II and III are 16-bit. Variations include the original MegaSquirt, MegaSquirt II (MS-II) and the latest MicroSquirt. The MicroSquirt is the same as MS-II but in a small sealed case. Note that "MegaSquirt" may refer to the hardware board, or to the software code. For example, Megasquirt-II code can run on the MegaSquirt-I board.

MegaSquirt II can do multi-coil, EFI and boost. GM wasted spark needs no upgrade (use two GM coils for a four-cylinder) or a Ford EDIS 4-tower coil. For COP it needs an optional upgrade card or controller (see COP).

Megasquirt III adds multiple selectable tables, USB control, sequential EFI. It also has drivers for COP right on the processor card (which is an extra option on MS2).

All use a serial cable to program/monitor. Megasquirt 3 can also use USB.


Buy MegaSquirt II (or MicroSquirt) fully assembled about $400 USD or $500 AUD off eBay.

The MegaSquirt controller is a relatively low-cost -- relative to other aftermarket engine computers. MegaSquirt kits start at about $200 USD.

MegaSquirt USA $200-$700
MegaSquirt AUS $400-$1200

From least expensive to most:

  1. OEM engine controller (used, $25-up) such as GM ECU
  2. MegaSquirt solder-together kit ($140-up)
  3. MegaSquirt completed product ($240-up)
  4. MegaSquirt-II hardware kit ($250-up)
  5. MegaSquirt III kit ($380)
  6. MegaSquirt-II assembled ($400)
  7. MicroSquirt ($400)
  8. MegaSquirt III assembled ($550)
  9. HALtech, Wolfe, and other aftermarket "custom" ECU systems ($700-$2500)

MegaSquirt software has evolved to the point where it is arguably as sophisticated as the more expensive designs.

The newer MegaSquirt-II board from 2005 has hardware that matches the more expensive designs, notably:

  • Expanded Ignition control for virtually any OEM ignition system
    • MegaSquirt-I board, running MegaSquirt-II code, can also do several types of distributorless crank-trigger ignition
  • CAN-bus support
  • More memory on the newer processor, allowing larger tuning tables
Haltech ECU
* $939 AUD and up
* proprietary
* professional help and documentation
* phone support available
MegaSquirt ECU
* about $700 AUD fully assembled or $500 mail order from USA
* open source
* user-based documentation
* only recommend to DIY users (or install by experienced shop)

Club Users


Many users choose the solder-together MegaSquirt Kit. The Kit is about half the price of an assembled unit.

  • If you have ever successfully soldered any electronic kit, even a simple one, you should be able to assemble a MegaSquirt.
  • Time to assemble is about 6-10 hours for an "average" person
  • As with any other universal engine controller, the user will have to careful select and configure part, then tune the system. It can be difficult to get the tuning "right".


When do you need a MegaSquirt? If you are using EFI you will need some kind of controller for it. If you are adapting an OEM fuel injection system, you can use the OEM computer which is cheap at the wreckers. But for highly customized engines, MegaSquirt will give you that fine tuning.

Crank Trigger and Multiple Coils

Question: I want to fit crank-trigger or coil-on-plug ignition. Is MegaSquirt for me?

Answer: Yes, MegaSquirt can control the ignition even if you don't have EFI. You can also use MegaJolt-EDIS instead which is less expensive. See COP for more MegaSquirt information.

  • MegaSquirt 3 can fire four separate coils directly
  • MegaSquirt 2 can fire multiple coils through an ignitor like the inexpensive Bosch 211 or the Nissan CA/SR ignitor
  • You can also do Crank Trigger with a single coil (using a distributor) with no extra hardware needed -- just set the MegaSquirt ignition input to the trigger and don't connect the distributor signal

14632.jpgAlbum click to view

For the old MegaSquirt-I, you may need to download the MegaSquirt-II code (MegaSquirt-II code can run on a MegaSquirt-I, and will control spark), or the software "MegaSquirt-N-Spark Extra" (MSnS-E) or other alternative software.

Board Versions

  • V1: original board revision, no longer available
  • V2.2: V2.2 is printed in the upper left corner of the printed circuit board
  • V3: can be fitted with MegaSquirt-I (8-bit) processor, or with MegaSquirt-II (16-bit) processor
  • V3.57: MegaSquirt II surface-mount board (non-kit board)

Parts Needed

  • EFI system, your choice of manifold, injectors and throttle body. MegaSquirt can handle most brands of injectors
  • Megasquirt unit
  • For a kit: It is highly recommende to buy or borrow a Stimulator to test your board during the put-together phase. The Stimulator ($45-up kit) emulates all the engine sensors to fully test each part of your kit board. Expert solderers/kit builders may choose to skip this.
  • Wires to wire it together ($0 if you have wiring sitting around, $65 new)
  • Oxygen sensor (optional but recommended)
  • MAP (vacuum) sensor or TPS (throttle position) sensor. Again, any brand (Ford, GM, Nissan, etc) may be used.
  • Air temp sensor
  • Water temp sensor
  • Boosted engines: High-bar MAP sensor for over 1.5 bar ($65)
  • Windows-based PC or laptop to run the MegaTune software to configure your system
    • Serial RS-232 "COM port" cable (about $5 new)

The sensors are usually the General Motors type, although you can recalibrate the controller to use other brands. Remember to "Keep it all Nissan".

Price estimate, assuming you have or can borrow a laptop and cable:

  • $200 for kit with case, all extra sensors from junkyard
  • $440 for MS-I hardware, wiring kit, and new sensors
  • $600 for MS-II hardware, wiring kit, and new sensors

  • Professional installation and tuning: Add ?


Where can I buy a MegaSquirt? From an authorized seller. See the list at

You can also find pre-assembled units on eBay, however beware they often cost more than from an authorized seller.

$840 AUD or $400 USD. The MicroSquirt V3 is basically a pre-built MegaSquirt 2 in a smaller package so you can use either documentation. 

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This page has been accessed 25,194 times. This page was last modified 01:56, 8 May 2019. Content is available under Datsun 1200 Club.