How to Megasquirt your 3G Hemi

Uhcoog1 said
Yes, it will run the fuel side alone. I cant recommend running fuel and spark on different computers- increases the cost and requires extra work to tune. Now if you started with a carb and swapped to EFI and wanted to keep the spark you already have, that's different.

This is exactly what I did. Started with a carb swap because I didn't want to upgrade the whole fuel system to high pressure (because if I did I wanted to go in-tank pump and didn't have the money at the time). I also had an awesome deal on an Megasquirt setup fall into my lap and couldn't pass it up. This all happened around the time I got my job out of college as well, so I suddenly had some money to play with and could afford the new fuel tank complete with pump.

Just running the fuel with the MS is actually super easy with an MSD running the ignition. Granted you're kind of limited to batch injection as opposed to sequential with this setup (unless it's possible to splice into the cam and crank sensors). The MSD uses the cam and crank and you just feed the tach output line of it into the Megasquirt for an rpm signal. You still need the coolant temp, air temp, vacuum, and throttle position, but those are easy enough to do. Had mine running this way for a few years now and have been really happy. The fuel control isn't quite as precise since you're not running sequential, but it seems to run consistent enough.

I'm still curious if anyone has tried this http://www.fuelairspark.com/fas/multiport-retro-fit-ez-efir-kit.html. It's a self tuning setup that uses a stock fuel injection configuraiton instead of the typical "throttle body with injectors built into it" retro-fit that are aimed at older carbed engines. Granted you'd need ignition control and to convert to a wired throttle body, so you might be looking at a similar price point as an all-in-one ECU, but it's potentially another option. I was really heavily looking into this before the Megasquirt dropped into my lap.