samplez/tunie/FLASH_DAY.md

Flash procedure — Arrow 2-1 + SAI/O2 delete

Pull this up offline, no signal needed. Written 2026-09-08 for the Lonelec OBD2 adapter attempt. Checksum re-verified valid immediately before writing this doc — computed=748a stored=748a MATCH.

0. The file

tunie/research/reference-maps/derived/20262-arrow-delete-composed.hex

• Base: 20262, TuneECU's own official Arrow 2-in-1 calibration.
• SAI + both O2 sensors disabled (device flags).
• Two idle-mixture (Idle Fuel Trim/CO) bytes corrected toward richer.
• Flash checksum patched and verified valid.
• What it is NOT: the main VE fuel tables (the ones governing fueling across the rev range) are untouched stock-Arrow calibration. This is the correct, safe starting point — not a finished tune. Expect a wideband pass later, not perfection today.
• Safe to flash regardless of whether the O2 sensors are physically installed or removed — SAI/O2-off is a software flag the ECU obeys either way (see prior session notes if you want the full reasoning).

1. Preconditions — confirm every one before connecting

• Battery tender/maintainer connected (real smart tender, not a bare trickle charger).
• Phone plugged into a charger and staying plugged in for the entire session — not just charged beforehand. TuneECU re-checks phone battery live at the moment you tap reprogram (must be ≥16%, or 0%/failed-read, which also passes); a mid-session drain is what most likely blocked a prior attempt, independent of the bike itself.
• Pull the headlight AND taillight fuses — reduces electrical load during the write, which matters more here than for a plain read: a genuine ECU-side busy/reject (KWP negative response, NRC 0x21 busyRepeatRequest) is a real failure mode tied to voltage sag under load, not resting voltage. Fuse numbers are bike-specific, check the fusebox cover.
• Ignition on, engine off, kill switch in RUN position — confirmed root cause (2026-09-09). The "Unable to open programing session (Battery low?)" / ERR_PSESSION error chased at length in an earlier session turned out to be caused by the kill switch being in the OFF position, not battery voltage, not the cable. Check this first, before anything else on this list, if the error recurs — it's the simplest and now-confirmed explanation.
• Lonelec adapter connected and confirmed talking (see Step 2).
• No other app/process holding the adapter's serial/BT channel.

2. Confirm the link before touching anything programming-related

Same principle as every prior session: prove the link is alive with the lightest possible check before risking a real operation.

• Open TuneECU, connect via the Lonelec adapter, and get to a normal live diagnostics / read screen first. Confirm you can read ECU ID and current map info cleanly — this is the same "read" capability that already worked with the old Bluetooth vLinker adapter, so it's a low bar, not the real test.
• If diagnostics don't come up clean, stop here. Don't proceed to programming on a link that hasn't proven itself first.

3. Read/backup the current map before writing anything

• Use TuneECU's own Read Map to pull the bike's current calibration and save it locally. This is your rollback reference and also confirms end-to-end read capability on this exact adapter before you ever risk a write.
• Note the map ID it reports — should be a stock production/aftermarket ID (20187/20191 family) unless it was already flashed.

4. Load the tune file

• In TuneECU, open 20262-arrow-delete-composed.hex (the file from Step 0).
• Before writing, visually confirm in the app's map-info display:
  • SAI: off
  • O2 Sensor / O2 Sensor (2): off
  • Checksum: should show valid (not flagged *No-OEM/Error) — if it does show an error here despite our own checksum.py confirming valid, stop and re-verify rather than overriding it.

5. Reprogram

• Tap reprogram. Expect TuneECU's standard confirmation dialogs (write-caution / void-warranty) — confirm through them, that's normal.
• Do not disconnect the adapter, close the app, let the phone sleep, or turn off ignition once the write actually starts. A programming session interrupted mid-write is the one genuinely bad outcome here — everything upstream of this point has been reversible; this step is not.
• Watch for the "Battery low?" / ERR_PSESSION message specifically — check the kill switch is in RUN first (confirmed root cause, see Section 1). If it recurs with the kill switch already correct, new adapter, phone charging, and fuses pulled, that's when to check bike voltage under load (multimeter clipped on during the attempt) rather than assume it's the same cable issue as before.
• Let it run to completion. Do not interrupt for anything short of a genuine emergency.

6. After a successful write

• Read the map back and confirm the ID/checksum match what you just flashed.
• Check DTCs — some may appear immediately after a flash and clear themselves on the next few ignition cycles; don't panic at one DTC right after writing.
• Idle the bike, listen/watch for anything obviously wrong (stalling, extreme richness/leanness, warning lights) before riding it anywhere.
• Turn ignition off, remove the tender, reinstall the fuses you pulled.

7. If the write fails partway through

• Do not panic-disconnect further. Per our own RECOVERY_MODE.md research: TuneECU has a dedicated Recovery function specifically for this — same underlying mechanism as a normal reprogram, gated by whether the currently-loaded file decodes as valid (not by live ECU state). If TuneECU offers "Run the ECU Recovery?", that's the expected, designed-for path — not a sign everything is lost.
• If recovery also fails to reach the ECU at all: this is exactly the scenario v-ladimir/audprog (AUD debugger, SH705x un-brick via PCB debug pins) exists for — a real, known backstop, not guesswork. Not needed unless recovery mode itself can't establish contact.

Quick reference — exact paths

Tune file:  tunie/research/reference-maps/derived/20262-arrow-delete-composed.hex
Checksum verify (if you want to re-check locally before flashing):
  cd tunie/research/reference-maps
  /Library/Frameworks/Python.framework/Versions/3.10/bin/python3.10 checksum.py derived/20262-arrow-delete-composed.hex