I'm glad there's enthusiasm for an "inexpensive" approach to fuel injection and ignition. If I get it working, I'll be glad to share the problems, solutions and limitations encountered along the way. I also very much respect the "if it ain't broke" approach.
The Tunerstudio software that works with Speeduino and the Megasquirt siblings has an autotune feature. You set up a spreadsheet (RPM x Manifold Air Pressure) and fill in the target air fuel ratios you want. Then you just drive around and the software adjusts your fueling to try to achieve the A/F targets. It worked well the last time I did serious tuning (2010).
If I remember correctly, you still need to fiddle with the acceleration enrichment map to get rid of the lag and as Ed noted, the idle air table (think of it as an electronic choke). When I lived in Rhode Island, idle air was a big deal because of the wide temperature ranges. Here, I've brought the wiring out in case I need to add it, but don't think I will.
I've run into some problems with my CBP Panchito manifolds that slowed me down today. They don't fit like the cheap eBay Chinese set I used for mock up, so a lot of grinding is getting done. It proudly says USA on the side, but you'd think they'd clearance the sides so a 13mm nut could actually make a full revolution. Heck, that's behind "one flat at a time" territory.
Ok, enough complaining, I'm still having fun.
I spent the morning building out the wiring harnesses for the fuel injectors, intake air temperature sensor and throttle position sensor. I've got the version of Speeduino that has a 40 pin IDC connector on the board. I bought a connector with pigtails to get it out of the case and then I broke up the connections I needed into a number of color coded 6 pin - CHEAP - waterproof connectors. That way I can easily remove the Speedy if I needed to do a swap (I've got a spare) and you can easily break out the connections for troubleshooting using another pair of connectors wired back-to-back ( more than most of you want to know - if you want details PM me). That's how I came up with the location of the spark coils vs the location of the Speedy. It turned out that the coil jammed the missing tooth crank sensing circuitry INSIDE the case, not through the cabling. I put the coil on one side of the shroud and the Speedy on the other side. Fiberglass doesn't shield interference worth a flip :-)
Spray paint color coded
Bag of 5 connectors - Amazon ZYTC 6 pin $12.20
Spartan 2 Wideband O2 controller w/sensor $125 from WTMTronics
