I've finally started to fully label / make sense of the MAC-11 code, define all the maps, etc. But the first step was to find what outputs/inputs were connected to the microcontroller.
Anyway I ended up completely disassembling the board to trace the whole thing, so I present to you - full MAC-11C schematic. It should be about 99% correct. Might have mixed up a couple traces. A couple components I missed values on, and some I wrote two values for
A couple of the grounds are 'dirty' at the engine, others are through the harness. I didn't differentiate that on the drawing of the main connector. I did on some of the outputs, but probably missed some. (the forked style ground symbol means engine ground)
I'll sort some of that out and post a v1.0.1 some day, but figured I better post it now before I change gears and lose interest in this project like usual.
Only a couple decades late:http://audi.slavtek.com/sch/MAC-11C-sch100.pdf
The design as a whole is really primitive, and it unfortunately uses a couple house-marked, undocumented, application specific ICs (the ADC/timer chip for reading sensors / controlling ignition; and the knock sensor IC).
More work along these lines to come, hopefully.