Low Slope and Breakpoint Patch

A1C calibration can be modified and configured to operate all EFI-SD4x ECUs in 4 cylinder, 6 cylinder and 8 cylinder configurations.
efloth
Posts: 436
Joined: 2021 Feb 15, 22:12
Location: Sacramento CA
Vehicle Information: 1991 F150 4.9L J1X 80lb Injectors E85
1995 F150 5.8L MOB1

Low Slope and Breakpoint Patch

Unread post by efloth »

I successfully implemented a low slope and breakpoint patch for J1X that is adapted to A1C below. I have not tested on A1C yet but here are the details if anyone is interested. The only thing may need to be worked out is the conversion math for breakpoint. I adjusted it by feel until I was happy with the results.

Code: Select all

Address: 508E
Original Hex: A3 F4 08 3A
New Hex: EF 6F 52 FF

Code: Select all

Address: A300
Original Hex: FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
New Hex: 89 9A 0A B4 D1 06 A3 F4 08 3A 20 04 A1 E0 E6 3A F0

Code: Select all

; --- A1C Hardcoded BKPT & ALOSL Patch (Unscaled 39.5 psi Deka 80s) ---

; Direct Compare
a300: 89, 9a, 0a, b4    cmpw Rb4, 0a9a    ; Compare Commanded Fuel Mass (Rb4) to 0A9A (BKPT: 0.00002714)
a304: d1, 06            jleu a30c         ; If Mass <= BKPT, jump to Low Slope logic

; High Slope Path 
a306: a3, f4, 08, 3a    ldw R3a, [Rf4+8]  ; R3a = AHISL (Original factory load from A822)
a30a: 20, 04            sjmp a310         ; Jump to Return

; Low Slope Path (Hardcoded)
a30c: a1, e0, e6, 3a    ldw R3a, e6e0     ; R3a = E6E0 (Hardcoded ALOSL: 101.46 lbs/hr)

; Return
a310: f0                ret               ; Return
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