[H-Man]

UPDATE: MPGunio is in but LCD making every dot on top row black and every dot on bottom row transparent. Any ideas?

When the display was working, I was getting occasional fuel usage spikes but doubling up on the number of pins used by ground and injector sense on the RJ45 I use for a connector to the car seemed to cut down on the spikes significantly.

It tracked milage acceptably and my butt dyno turns out to be quite good at telling when the car kicks into DFCO. AC: 50% more idle fuel use, headlights 10% more idle fuel use. Cold engine: 100% more idle fuel use.
EDIT: I flashed a modified version of the basic blink arduino sketch that blinks every pin and I found that pins D10 and D11 are dead (I used D10 and D11 in place of D12 and D13 since I'm using a arduino nano which has a LED on D13 and thus I seem to have difficulty getting it to output data fast enough) judging by how they are the only output pins that don't blink the LED I hook up.

I'm using the nano so I have extra pins that I can remap things to (D2-13 and A0-A7 gives 20 pins vs the 18 the uno has)
Not worried about the microcontroller frying anything because I have 100k ohm between it and the car on input lines (VSS, injector) and a diode on the power supply line, plus I wired the RJ45 so even if someone uses a crossover cable and plugs a laptop in, nothing will happen.
EDIT2: Not even worth the effort to fix seeing how I can build a new one for under $15 and fix my previous mistakes.