I’m considering an EFI conversion – converting my car from carbs to EFI – what do I need to consider?


Your fuel system will need to be converted to a high pressure system suitable for fuel injection (around 43.5 psi for MPI, less for TBI if you go that route).  If you can get a TBI unit (with TPS) that bolts to your manifold, that may be the simplest route (though their likely will be more power and better economy/emissions in a good MPI setup), otherwise you’ll need to buy or fab up an intake manifold and throttle body with TPS, fuel rails, etc.    We don’t carry intake manifolds at this time, though we do carry many of the fuel system components you will need, and of course the engine management systems and accessories.

FOR FUEL AND IGNITION CONTROL– We’d suggest running a MegaSquirt-II, or MegaSquirt-III, using the PCB v3 or v3.57.  You’ll need a compatible Crank Angle Sensor to determine engine position and RPM from as well as some way to fire the ignition — with the MS2 this is generally a distributor based solution or the Ford EDIS or GM DIS distributorless solutions which could be adapted to your engine (most adaptations use EDIS which also uses it’s own 36-1 Crank Angle wheel which can be mounted on the crank pulley).  You can read more about ignition options in the MS/Extra documentation at http://msextra.com/doc/index.html.

FOR FUEL ONLY– You could run any of the MegaSquirt ECUs, the MS1, MS2, or the MS3.  We’d recommend PCB v3.0 or PCB v3.57.  Pickup up your ignition signal from the negative terminal of the coil, run your IAT, CLT, TPS, and O2 sensor inputs to the MegaSquirt, calibrate the MS to the sensors if they are not GM sensors and start tuning.

If you haven’t yet we’d again suggest taking a look through the MS/Extra version of the manuals at http://msextra.com/doc/index.html as it will go into detail about most aspects of the conversion/installation/configuration/tuning and help to make things clearer.

Here’s a list of what most people would commonly pick up:  We’ll list what we see as ‘required’ and then some ‘recommmended’ and ‘optional’ components.  Then we’ll provide a link that goes into some detail on why we made these recommendations and that will also help you to decide on the optional components.


(Note you can substitute DIY kits for the below to save some cash and learn more about your EFI system, and electronics in general, in the process.)


along with:

‘Highly Recommended’

Innovate LC-2 Digital Wideband Controller with Sensor

12′ MegaSquirt Wiring Harness (MS1 / MS2 Ready)  and possibly the MS3X Harness as well if you’re running the MS3X board.


MegaSquirt Relay Board – Assembled Unit

MegaSquirt-I Relay Cable (if you’re using the relay board and cable, you don’t need the standard MSHarness12, see note in product description)

GM Open Element IAT Sensor with Pigtail

GM Closed Element CLT / IAT Sensor with Pigtail

USB to Serial Adapter


Here’s the link mentioned above with more info on each —

What do I need?

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