uhryniuk
80c9373ded
The NO-SAI-NO-O2 reference map bundles SAI + O2 + airbox deletes, so it validates the three flag bytes as a GROUP but doesn't isolate O2 individually; no single-mod map exists and the x.a() device-layout branch for this ECU is too nested to trace. - SAI @ 0x53801: confirmed (code lc() -> Devices[0] via fe[33], + the delete map). - O2 @ 0x53818/0x53819: probable (2 O2 sensors declared off <-> 2 adjacent bytes cleared; 865 has no air-flap so airbox removal is fuel-only). Viewer now shows confirmed/probable badges and a warning that flags alone are not a tune: O2 delete forces open-loop and needs fuel enrichment, so prefer flashing a complete matching delete map over hand-toggling a stock one. See DEVICES.md.
3.2 KiB
Device-enable flags (SAI / O2 / lambda) — validated
How they were found
Both stock reference maps (20187, 20188) have SAI and O2 active, so diffing them can't reveal the delete flags. The confirmation came from a community map that explicitly disables them:
20188Map2009AIRBOXBONNY.hex — "Bonneville, aftermarket exhaust, mechanical
odometer, NO AIR BOX, K&N, British Custom mufflers, NO SAI, NO O² SENSORS".
Same base as stock 20188, so the diff isolates the deletes.
Diff (flat ROM) of that map vs stock 20188 = 0.36%, split into:
- the fuel tables (airbox/K&N enrichment — expected), and
- a small cluster in the device-config region at 0x53801…0x53819.
The flags
They are a byte-boolean array at flat-ROM base + fe[33] (= 0x50000 + 0x3801 = 0x53801), one byte per device, 1 = enabled, 0 = disabled.
The delete map changed exactly three bytes from 1 → 0:
| Flat-ROM offset | Stock | Deleted | Device |
|---|---|---|---|
0x53801 |
1 | 0 | SAI (Secondary Air Injection) |
0x53818 |
1 | 0 | O2 sensor |
0x53819 |
1 | 0 | O2 sensor (2) |
SAI is the first flag in the array; the two O2 sensors are the last two —
consistent with the Devices resource order (SAI = index 0; O2 Sensor / O2
Sensor (2)). The three-byte change matching "NO SAI, NO O²" is unambiguous.
To disable a device: set its byte to 0. (The 0x5369C/0x536AB bytes that
also changed are idle/open-loop trim that comes with removing the O2 feedback,
not device-enable flags.)
Editing / export
The downloaded .hex format's integrity is the dc stream cipher + the unpack
directory; the caXX bytes in the header/tail are map-ID metadata, not a
calibration checksum. So a device toggle = flip the byte in the flat ROM, re-pack
to the decoded layout, and dc-encode back to .hex. (The separate ECU flash
checksum is computed at flash time and is out of scope for the read/edit tool.)
Confidence
- SAI = 0x53801: ~90% (high). Two independent confirmations: the device-name
logic in
l.javalc()resolvesDevices[0]=SAIviafe[33]to exactly 0x53801, AND the real NO-SAI map cleared precisely that byte. - O2 sensors = 0x53818 / 0x53819: ~80% (probable). The map declares "NO O²
SENSORS" (the twin has two) and exactly two adjacent boolean bytes cleared
beyond SAI; the 865 has no air-flap, so airbox removal is fuel-only (no flag).
Not independently isolated — no single-mod reference map exists, and the exact
x.a()device-layout branch for this ECU (i27=72) is too deeply nested to trace reliably.
The real-world caveat (more important than the labels)
Correct flags are not a good tune by themselves. Disabling O2 forces the ECU open-loop: it stops live fuel trim and runs entirely on the base fuel map. Stock maps assume closed-loop trim at idle/cruise, so an O2-delete on an otherwise stock map can run lean/rough. A proper delete pairs flags-off with fuel enrichment (which is exactly why the AIRBOXBONNY reference map also changed the fuel tables).
Recommendation: flash a complete, known-good delete map matching the hardware (exhaust/filters), not hand-toggled flags on a stock map. The checkbox editor is for understanding/building a map, not a one-click safe delete.