I have succeeded in getting exact timing in the ECU KWP2000 connection code for fast init. I ended up using the bit bang methods in the FTDI D2XX driver to accomplish the exact timings. Logic analyzers are a great tool.

Problem is, I still can’t connect to the 2002 Audi S4 ECU. So I decided to contact some people who write professional VAG diagnostic tools. They confirmed my suspicion that KWP2000 fast init is not properly supported on all VAG ECUs. Their recommendation was to use the slow init method instead.

Alright, now I know what the problem is, and with my mad bit banging FTDI skills, I hope get the slow init method done pronto!