Diagnostics
Diagnostic Trouble Code (DTC) Retrieval and Reference
Complete guide for retrieving and interpreting diagnostic trouble codes (DTCs). Learn how to diagnose OBD0, OBD1, and OB...
Hondata ECU Tuning Systems
An overview of Hondata as a commercial provider of Honda ECU development, reprogramming, and tuning solutions.
Honda OBD0 and OBD1 ECU Troubleshooting
A comprehensive troubleshooting guide for diagnosing Honda OBD0 and OBD1 ECU issues, including solid CEL lights, diagnos...
OBD0 Limp Mode Diagnostics and Operation
An overview of OBD0 Limp Mode, a fail-safe operating state triggered by major ECU malfunctions that limits engine perfor...
Honda OBD0 and OBD1 ECU Datalogging Overview
Overview of OBD0 and OBD1 Honda ECU datalogging methods, including serial communication interfaces, historical software,...
Honda ECU Speed Limiter Operation
An overview of how Honda ECU speed limiters function by monitoring the Vehicle Speed Sensor (VSS) and the methods used t...
1991 PM6 ECU Diagnostic LED (CEL) Blinking Routine
Technical explanation of the diagnostic LED/CEL blink routine inside the 1991 OBD0 PM6 ECU codebase.
P2P
Technical overview of the P2P OBD2 Honda Civic EX ECU, covering stock bin configurations, ignition timing maps, and hard...
Troubleshooting a Solid CEL
Diagnose and resolve a solid Check Engine Light (CEL) on Honda OBD0 and OBD1 ECUs, typically caused by hardware failures...
ASM662 Assembler and Disassembler
ASM662 is an assembler and disassembler tool for Oki 66201, 66207, 66301, and NEC 66911 microcontrollers used in various...
Oki 66K Architecture Reference
Technical documentation and architectural reference for the Oki 66K microcontroller series used in Honda ECU hardware.
`29C256`
the ATMEL AT29C256 chip is the de facto FLASHROM chip in use. It uses a 5V programming voltage, can be erased repeatedly...
Honda ECU Chipping: Essential Tools and Hardware
A comprehensive guide to the tools and hardware required for Honda ECU chipping, including essential soldering equipment...
DIY Engine Simulator for ECU Bench Testing
A comprehensive guide to building a DIY hardware Engine Simulator for bench-testing and debugging Honda OBD0, OBD1, and...
Honda ECU Backup Processor Reference
An overview of the Honda ECU backup processor, a redundant system designed to maintain engine operation during critical...
Mugen XE5 ECU Technical Reference
Technical overview of the Mugen XE5 ECU, a race-oriented variant derived from the PM7-0330 platform designed for ZC engi...
OBD0 MPFI ECU Architecture
Technical overview of the OBD0 MPFI ECU family, featuring Oki 80C154/83C154 architecture and common hardware components...
Throttle Position Sensor (TPS)
How the Throttle Position Sensor (TPS) works, how to calibrate/adjust it, and troubleshooting common TPS issues.
Troubleshooting Honda ECU Datalogging (CN2 Debugging)
Troubleshooting guide for Honda OBD1 ECU datalogging, covering hardware continuity, ROM configuration, and serial commun...
OBD1 ECU IACV Circuit Repair: R58, R59, and Q21
A comprehensive guide to diagnosing and repairing the IACV driver circuit on Honda OBD1 ECUs, specifically addressing bu...
PK2
Prelude OBD0 B20A ECU. Electronic Advance. External 27c256 ROM. oki 83c154 based pk2 ECU photo.: I posted the Options Cl...
1991 Honda PM6 ECU Reference
Technical reference for the 1991 Honda PM6 ECU, covering idle target configuration and onboard diagnostic LED troublesho...
Honda ECU Engine Simulator Reference
An overview of engine simulator hardware used to mimic engine operation for Honda ECU development and bench testing.
OBD0 Code Compatibility
A guide to OBD0 Honda ECU code compatibility. Learn which ECUs can share code and how to successfully interchange binari...
Real-Time Programming (RTP) for Honda ECUs
Real-time programming (RTP) allows for live ECU calibration adjustments while the engine is running by replacing the sta...
1991 PM6 ECU Target Idle Routine Analysis
Technical analysis of the 1991 PM6 ECU target idle routine, including memory address locations and code structure compar...
AC Cut Routine
Author: evo (61.88.2.177) Date: 030403 22:15 After much thought, ive decided to share my AirConditioner Cutoff routine.
Adding Knock Sensor Circuitry to OBD1 ECUs
Step-by-step hardware guide for adding a knock sensor circuit to non-equipped Honda OBD1 ECUs using specific component m...
Auto Or Manual
A hardware/software interaction will determine whether a program in an ECU behaves as a manual or auto.
ECU Boost Table Expansion
Learn how to utilize ROM editor scripts to expand stock ECU fuel and ignition tables for forced induction applications.
ECU ROM Checksum Calculation and Verification
A checksum is a fundamental error-checking mechanism used in Honda OBD0 and OBD1 ECUs to verify ROM integrity by summing...
Engine Coolant Temperature Sensor Reference
Technical reference for the Engine Coolant Temperature (ECT) sensor, including ECU lookup tables and operational charact...
Honda ECU Code Compatibility and Cross-Platform Flashing
A technical guide to Honda ECU code compatibility, detailing how ECUs within the same generation and hardware family sha...
OBD1 ECU Hardware Overview and Compatibility
A technical overview of OBD1 ECU electrical compatibility, hardware architecture, and modification requirements for Hond...
Oki 83C154 Microcontroller
Technical overview of the Oki 83C154 microcontroller used in OBD0 MPFI ECUs, including compatibility and replacement opt...
Oki 8XC154 A5h Opcode Analysis
Technical analysis of the A5h opcode in Oki 8XC154 microcontrollers used in Honda ECUs and methods for standard 8051 com...
Popol Vuh: Foundational ECU Documentation
An overview of the Popol Vuh project, the foundational documentation effort that served as the catalyst for the Honda EC...
Pre-Ignition and Detonation (Engine Knock)
Explains the physical mechanisms, differences, causes, and prevention methods for engine pre-ignition and detonation (kn...
Removing MAP Sensor Software Limits (Uncorking)
Learn how to modify stock ECU code to remove the MAP sensor division limit, allowing the ECU to read boost pressures up...
Troubleshooting Common TurboEdit (TE) Issues
Troubleshooting guide for common configuration errors, MAP sensor column rescaling issues, and VTEC bytes modifications...
Using Nico Analyze for ECU ROM Map Identification
A technical guide on using Nico Analyze for ECU ROM map identification, including configuration of offsets, column setti...
Honda PH3 ECU Technical Reference
Technical reference for the Honda PH3 OBD0 ECU, covering hardware specifications, processor architecture, and jumper con...
Speed Density
What is a Speed Density engine managment scheme? Speed Density systems calculate the amount of air entering a motor usin...
Honda ECU Serial Communication Adapters
Honda ECUs utilize 5V TTL signaling for serial communication. This guide outlines the necessary serial adapters required...
OBD0 Stock ECU Serial Datalogging
An overview of the OBD0 ECU serial communication protocol, including baud rate limitations and the implementation of Tim...
Application Programming Interface (API) Reference
An Application Programming Interface (API) is a set of functions within a library or DLL that allows software to perform...
Batronix USB Programmer Technical Guide
Technical overview and operational guidelines for using the Batronix USB Programmer to read and write ECU EPROM and Flas...
Disabling VTEC VSS Check on P30 ROMs
Technical guide on bypassing the Vehicle Speed Sensor (VSS) check within the VTEC routine for OBD1 P30 ROMs.
EEPROM Technical Overview
A technical overview of Electrically Erasable Programmable Read-Only Memory (EEPROM) and its function in ECU calibration...
EFI Theory and Engine Management Reference
A curated collection of technical resources covering EFI theory, engine management systems, and automotive diagnostics.
Honda ECU Air Conditioning Control Routine Analysis
Technical breakdown and assembly commentary for the Honda ECU air conditioning control routine.
Honda OBD1 ECU Label Identification
A comprehensive guide to decoding Honda OBD1 ECU part numbers to identify engine compatibility, market origin, and trans...
Intel HEX File Format Overview
An overview of the Intel HEX file format, an ASCII-based standard used for storing machine language code and data for EC...
Joel Eck
Technical profile and contact information for Joel Eck, contributor to Honda ECU tuning and diagnostics documentation.
Manual Checksum Correction for Honda ECUs
Learn how to manually calculate and correct 8-bit checksums for OBD0 and OBD1 Honda ECU ROM files to resolve checksum er...
OBD0 16-Bit RPM Conversion Formula
Technical reference for converting engine speed (RPM) to 16-bit hexadecimal values for OBD0 Honda ECU tuning and ROM mod...
OBD0 NEC BACK0004 Processor Reference
The NEC BACK0004 processor serves as a secondary backup controller in OBD0 MPFI ECUs, managing engine operation during l...
OBD0 VTEC ECU Reference: PR3 and PW0
Technical overview of OBD0 VTEC ECUs, specifically the PR3 and PW0 models used in 1989–1991 B16A1 applications.
OBD1 P72 ECU Debug Mode and ROM Configuration Switches
Technical analysis of the diagnostic debug mode and ROM configuration byte switches in the OBD1 Honda P72 ECU.
PM8 ECU Technical Reference
Technical overview of the Honda PM8 ECU found in 1988–1991 CRX HF models, detailing its unique hardware configuration an...