Cars
Honda OBD1 P28 ECU Internal Schematics
Written transcription of the Bomarc 8-sheet internal PCB schematics for the Honda OBD1 P28 ECU (37820-P28-A51).
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...
Honda OBD0/1 ECU Component List
Reference of the components on Honda/Acura OBD0 and OBD1 ECU boards: IDs, types, specs, and repair notes.
Engine Coolant Temperature (ECT) Sensor Reference
Technical overview of the Engine Coolant Temperature (ECT) sensor in Honda engines, including its role in fueling, ignit...
OBD1 Honda P28 ECU Reference Guide
A hardware and software reference guide for the USDM and EDM OBD1 P28 SOHC VTEC ECU, the industry standard for custom Ho...
Hondata ECU Tuning Systems
An overview of Hondata as a commercial provider of Honda ECU development, reprogramming, and tuning solutions.
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 Distributor Operation and Function
A comprehensive overview of Honda distributor operation, function, and role in the ignition system across OBD0, OBD1, an...
Honda OBD0 and OBD1 ECU Troubleshooting
A comprehensive troubleshooting guide for diagnosing Honda OBD0 and OBD1 ECU issues, including solid CEL lights, diagnos...
Intake Air Temperature (IAT) Sensor Reference
Technical overview of the Intake Air Temperature (IAT) sensor and its critical role in air density calculations and fuel...
Vehicle Speed Sensor (VSS)
The Vehicle Speed Sensor (VSS) sends speed pulses to the cluster and ECU. Diagnosing speedo failures and VSS-related VTE...
OBD1 ECU Code Compatibility Guide
Guide to OBD1 ECU code compatibility, detailing VTEC requirements, sensor exclusions (O2/Knock), and regional (USDM/JDM/...
Throttle Position Sensor (TPS)
How the Throttle Position Sensor (TPS) works, how to calibrate/adjust it, and troubleshooting common TPS issues.
Electrical Load Detector (ELD) Operation
The Electrical Load Detector (ELD) monitors vehicle electrical consumption to allow the ECU to proactively adjust idle p...
Introduction to ECU Chipping
A comprehensive guide to the hardware and software fundamentals of socketing and chipping OBD0 and OBD1 Honda ECUs.
Basic Concepts of Honda Engine Management
An introductory guide to electronic engine management concepts for Honda enthusiasts, covering air, fuel, spark, and sen...
Honda ECU Identification and Compatibility FAQ
A foundational reference for identifying Honda ECU families, understanding compatibility, and navigating common ECU part...
Honda ECU Serial Datalogging (`CN2` TTL Header)
Learn how Honda OBD1 ECUs communicate with tuning laptops via serial TTL signals (CN2 header), including pinouts, settin...
VTEC Solenoid
The VTEC spool valve solenoid activates high-cam lobe profiles. How the ECU triggers VTEC, pressure switches, and troubl...
Turbo Compressor Map
Guide to reading and interpreting turbocharger compressor maps for matching turbochargers to Honda engine performance go...
Understanding ECU Fuel and Ignition Maps
An introductory guide explaining how fuel and ignition tables (maps) are structured and interpreted inside Honda ECU ROM...
Honda OBD1 ECU Reference (1992–1995)
Technical overview of OBD1 (1992–1995) Honda Engine Control Units, including popular ECU models and their applications.
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...
Guide to Honda ECU Hardware Modifications
A comprehensive index of hardware modifications for Honda OBD0 and OBD1 ECUs, including VTEC conversions, IAB additions,...
Honda OBD Generations Guide (OBD0 to OBD2)
An overview of Honda OBD0, OBD1, and OBD2 diagnostic systems, highlighting key differences, connector layouts, and code...
Closed-Loop Fuel Control
Closed-loop fuel control basics for Honda tuning, including open-loop fallback, wideband and narrowband targets, fuel tr...
Tuning Ignition Timing on Honda ECUs
A technical guide to ignition timing calibration on Honda ECUs, covering combustion mechanics, MBT, and the relationship...
Vehicle Speed Sensor (VSS) Technical Reference
Technical overview of the Honda Vehicle Speed Sensor (VSS), including signal characteristics, diagnostic procedures, and...
Automatic to Manual ECU Conversion
Overview of converting automatic Honda ECUs for manual transmission use through software or hardware modifications.
OBD2 Diagnostics Standard
Overview of the OBD2 standardized diagnostic protocol (1996+), including its standardized DLC port and diagnostic report...
Cylinder Position (CYP) Sensor Operation and Diagnostics
An overview of the Cylinder Position (CYP) sensor function, location, and its critical role in sequential ignition timin...
Data Link Connector (DLC) Communication Protocols
Technical specifications of the Honda OBD1 Data Link Connector (DLC) communication protocol, voltage levels, capacitance...
USB-to-TTL Serial Converter Guide (`FTDI` & CP2102)
How to configure and troubleshoot USB-to-TTL serial converters (such as FTDI or CP2102 chips) for reliable ECU dataloggi...
Wide Open Throttle (WOT) Definition and Tuning Significance
Definition and technical significance of Wide Open Throttle (WOT) in Honda engine management, fuel mapping, and diagnost...
ECU 0-5V Wideband O2 Input Modification
Modify your Honda ECU to accept a 0-5V wideband O2 sensor input by bypassing the internal Op-Amp voltage limiting circui...
Fuel Octane Ratings and Engine Performance
Understanding fuel octane ratings and their impact on Honda engine performance, knock resistance, and ignition timing op...
Crome ROM Tuning FAQ
Frequently asked questions about Crome, a popular ROM editing and tuning software for OBD1 Honda ECUs.
Honda OBD0 and OBD1 ECU Datalogging Overview
Overview of OBD0 and OBD1 Honda ECU datalogging methods, including serial communication interfaces, historical software,...
Air-Fuel Ratio (AFR) Guide for Honda Tuning
An introduction to Air-Fuel Ratio (AFR) in internal combustion engines, explaining stoichiometric targets, rich vs. lean...
Honda ECU Sensors
A comprehensive overview of the primary and optional sensors utilized by Honda ECUs to manage fuel injection, ignition t...
Intake Air Bypass (IAB) System
An overview of the Intake Air Bypass (IAB) system, which optimizes engine performance by switching between long and shor...
OBD1 PR4 ECU Hardware Reference
Hardware layouts, component locations, and chipping instructions for the OBD1 Acura Integra PR4 ECU.
P27
Technical specifications and application overview for the P27 92-95 OBD1 Euro/Asian Civic ECU.
Atmospheric Pressure (PA) Sensor Technical Reference
Technical guide to the Atmospheric Pressure (PA) sensor in Honda ECUs, explaining its role in altitude compensation and...
Honda ECU Engine Simulator Reference
An overview of engine simulator hardware used to mimic engine operation for Honda ECU development and bench testing.
Calibration Window Overview
How the calibration window is organized in Hondata tuning software, including parameter groups, change indicators, right...
Parameters Window Overview
A practical overview of the parameters window in Hondata software, explaining which ECU settings it exposes and how it f...
A/C Thermostat Switch Bypass
Guide for jumping the A/C thermostat switch during A/C system troubleshooting or installation.
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...
Engine Coolant Temperature Sensor Reference
Technical reference for the Engine Coolant Temperature (ECT) sensor, including ECU lookup tables and operational charact...
Guide to EPROM and Flash ROM Burners
A technical guide to selecting and using EPROM and Flash ROM burners for programming 27C256 and SST 27SF256 memory chips...
Index of Honda ECU Connections & Pinouts
Index of Honda and Acura ECU connector pinouts, wiring diagrams, and harness conversion guides across OBD0, OBD1, and OB...
Mass Air Flow (MAF) Sensor
Technical explanation of Mass Air Flow (MAF) sensors, detailing their function and highlighting differences compared to...
OBD0 DOHC ZC PM7 ECU Reference
Technical specifications, board layout documentation, and stock ROM binaries for the OBD0 DOHC ZC PM7 ECU.
OBD1 Civic and Integra ECU Reference
Technical reference for OBD1 Honda Civic and Acura Integra ECU pinouts, sensor configurations, and diagnostic specificat...
P29 OBD1 ECU Technical Reference
Technical reference for the P29 OBD1 ECU, commonly found in JDM Honda Domani and Civic 25th Anniversary models equipped...
Throttle Position Sensor (TPS) Adjustment
A step-by-step procedure for adjusting the Throttle Position Sensor (TPS) to ensure accurate voltage output at idle and...
Acura Brand History and Overview
Overview of the Acura brand history and its evolution within the Honda automotive ecosystem.
Speed Density
What is a Speed Density engine managment scheme? Speed Density systems calculate the amount of air entering a motor usin...
Ghetto Dyne Tuning Platform
Historical overview of the Ghetto Dyne tuning platform and its transition to modern ECU tuning software.