General questions about customizing

[vristang]

I used several different ecu's to tune my own fox Mustangs (A9L, X3Z, CBAZA for a 2.3L n/a, to name a few), with either TwEECer or Moates QH. I don't mind using these moving forward, but since I will be tuning both a v8 and a 4 cylinder in the near future (hopefully), it will benefit me to have these 2 cars be as similar as possible.
I like Megasquirt because of price, and from what I understand, system flexibility (I have questions below on this however).
What I don't like about megasquirt is trying to figure out the differences between systems. There isn't a really good detailed technical spec sheet/comparison between the MS1/MS2/MS3. It is all written as hi-level advertising... I think I am figuring out what I need to know though, it's just slower than I had hoped.

My background: I work in Materials/structural test for a commercial aircraft manufacturer. I have written several versions of software applications for thermal control (PID based), data analysis/reporting, and monitoring of test rig activity. I have tuned my own 408w, as well as an N/A 2.3 running at first on a CBAZA ecu, but later switched to CZAJL (both are v8 ecu's). I messed around with Arduino stuff as well, but nothing more than exploring/playing.
I don't mind writing my own code, calibrating sensors, etc, as long as I don't have to use Ladder Logic. That is part of the fun of messing with control systems

So, that was long-winded... here are the questions I have right now...
Can I customize inputs to fuel and timing? For example, could I average 2 intake temperature inputs to correct fuel, instead of basing fuel adjustments on a single temperature input?
Can I create my own code for something like a fan controller, using a PWM for variable fan speed, and switch to relay control when desired (programmatically)? I would otherwise build this with Arduino, but would prefer it integrated with the ECU.
Could unused Fuel injector outputs be repurposed? Can the output hardware/channel be reprogrammed by the user? In other words, if using an MS3 on a 4-cyl car, could I use the other 4 injector channels for control of electric water pump/fan? Can I write my own code for control of these channels? If so, what programming language would be used?
When using the GPIO kit for output control, what programming language is used?

[billr]

Well, I'll throw out my opinions before somebody smarter joins in:

I, too, have no use for RLL; and you will not be burdened with it using/programming MS.

Don't consider anything but MS3, and I suggest the MS3 "kit". There are lots of (good) reasons for starting out with the latest hardware (MS3), and it really only costs about $100 more than the older MS2.

MS has "open" software, so if you can write code you can make it do pretty much anything you want. However, the MS3 feature set is so rich that you can "pretty much make it do anything you want" without ever touching the standard FW code!

Rather than special code, you may want to add some I/O buffer circuits if you have really unique needs. Many "standard" such circuits are already available from sources such as <jbperf.com> at a very reasonable price. You may find those so low cost that it isn't worth your bother to design and fab the circuit yourself.

As to specific questions about the GPIO or CAN add-ons and com to them, I can't really comment except to say that those are thoroughly covered by the MS folks; I just haven't had any need to use them.

[Six_Shooter]

I will start with suggesting you download Tuner Studio and look at the example projects for MS2 and MS3 so you can see the built in selections and abilities. I'm sure you'll go MS3, because of it's current capabilities, and future development. Keep in mind the example projects won't be the latest firmware. You can read the release notes for the latest firmware to see what new options may not be in teh example firmware.

You can download TS for free, and upgrade it later if you choose to go with MS and want the added features.

But to answer a couple of your questions, yes unused outputs can be repurposed for other uses.

there are ways to set up PWM fan control as well.