What is this little black box

It stays. Headlamp sensor page EL-177 in FSM

What made you go with MS3? Im gonna be selling my microtech soon

Ah ok, that means I need to sand it and paint it then. It is a bit rough looking.

I decided on Megasquirt because of a few things actually. I opted for the Megasquirt Extra addition, pretty much allows anything I can throw at it, a 3 step, 2 stages of nitrous, boost control, fan control, sequential injection, and probably my personal favorite bluetooth connection to my phone or tablet for gauging/data logging/tune loading.

Oh and GM sensors, I'll basically be running all GM sensors other than the crank sensor, TPS and MAP. I got the MAP Daddy 4BAR MAP upgrade too. Figure just being able to run cheap GM sensors is worth while, after replacing a MAF a few times lol

Sounds good. How much is all of the MS3 stuff gonna cost?

I picked up the MS3 with MS3X preassembled, MAP Daddy and knock module also preinstalled, both harnesses, the VG30 CAS compatible trigger wheel, boost control module, GM IAT, GM coolant temp sensor, and 1 aluminum bung for the IAT sensor for $1120 dollars

Not bad. It's really not that hard to install.

It doesn't look like it will be to bad, especially with the harnesses. They are all labeled. The main thing that has me stressed is figuring out what factory harness I can eliminate, what I need to keep and where to tie the MS3 unit in for the ignition switch and fuel pump circuitry. I'll get it figured out eventually lol.

you can try and reuse some of the factory ecu harness but I just removed the whole ecu harness when I installed my Microtech. For the fuel pump I just used a separate relay and also ran all new thicker wire from the battery to the relay (with a fuse in between) and a new thicker wire from the relay to the fuel pump. Thick ground wire on the -neg side of the pump to chasis ground close to the pump. Ecu trigger wire to relay and +12V when key is in ON position to relay. Easy.

Or study the FSM wiring diagram and see what wire goes where and reuse part of the factory harness.

Really I'm looking to eliminate all or most of all the factory ECU harness. Megasquirt has everything to replace it. I'm just wanting to keep the factory ignition circuit, fusible links, relays and such so I don't have to rewire all that. I figured I would likely need to do a new circuit for the fuel pump but wouldn't mind using the factory circuit. I'll go whichever route is easiest.