I'm working on a custom ECU flasher for ME7 using Python and pyftdi. My bench setup is solid and verified working with other tools — no issues entering diagnostic sessions or flashing.

✅ What’s Working
FTDI dumb mode properly initiated

SlowInit 5-baud sequence successfully sends 0x01

ECU responds with correct sync bytes: 55 01 8A

ECU ID block and version info are received over KWP1281

Transition to KWP2000 is attempted after sync and ID read

❌ Where It Fails
After sending StartDiagnosticSession (0x10) → 68 6A F0 10, I consistently receive echo responses or partial bytes (e.g., 68 6A F0, or other permutations)

Tried changing the SID from 0x10 to 0x11, adjusting delay before/after sending, and ignoring echo responses

Extended wait time before KWP2000 session and byte-by-byte response monitoring also applied

Still ultimately fails with:
[ERROR] Flash failed: [KWP] ECU did not enter diagnostic session after multiple attempts.

KW1281 handshake is tricky with tactrix though.