This index serves as a collaborative reference for memory addresses and ROM map definitions within Honda ECU firmware. Understanding these locations is essential for reverse engineering, customizing fuel/ignition maps, and developing performance firmware.

OBD1 ECU Map References#

OBD1 ECUs share a largely standardized architecture, simplifying the development of custom ROM analysis tools.

• Civic/Integra Platforms: Mapping for popular ECUs like the P28, P30, and P72.
• Performance ROMs: References for UberData and high-resolution P72 codebases.

OBD0 ECU Map References#

OBD0 ECUs require generation-specific map definitions due to the lack of standardization across early firmware.

• VTEC ECUs: Mapping for PW0 and PR3 units.
• Multi-Point Fuel Injection (MPFI): Mapping for PM6 and PR4 series ECUs.

Resources for ROM Development#

• Assemblers/Disassemblers: Tools like ASM662 allow for analyzing and reassembling ECU binary files.
• Conversion Formulas: Use the OBD1 Conversion Formulae0 or OBD0 Conversion Formula0 to translate hexadecimal ROM values into engineering units (RPM, fuel pulse width, spark advance).
• Compatibility: For information on running different firmware codebases on unintended hardware, refer to the OBD1 Code Compatibility Guide0.

Technical Note#

These memory locations are based on community-sourced reverse engineering. Firmware variations may exist between different production regions and ECU part numbers. Always verify address mapping against your specific ROM codebase before applying modifications.