I don't right now, unfortunately, but a writeup is next on my list of projects after the carputer is complete. I'll post it here if there's interest. For learning about the OBD protocol, though, these resources have been very helpful:

The ELM 327 data sheet (this is the chip in most OBD devices you'll find on amazon): http://elmelectronics.com/DSheets/ELM327DS.pdf

Wikipedia's article on OBD PIDs: https://en.wikipedia.org/wiki/OBD-II_PIDs

"A complete guide to hacking your vehicle bus on the cheap & easy": https://theksmith.com/software/hack-vehicle-bus-cheap-easy-p...

There's a PyOBD python module out there (my carputer is built in python), but it's a fairly simple process so I just rolled by own using pyserial.