For Honda Civic enthusiasts, particularly those working with the popular EG chassis (1992-1995 models), engine swaps are a common and exciting upgrade path. Often, this involves integrating newer, more powerful OBD2-generation B-series engines into these OBD1 vehicles. Understanding how to perform a 95 Eg Convert To Obd2 system is crucial for a successful and functional swap. This guide will provide a clear and concise breakdown of what you need to know to get your OBD2 engine running smoothly in your 95 EG Civic, focusing on practical steps and essential components.
Understanding the Basics: OBD1 vs. OBD2
The terms OBD1 and OBD2 refer to On-Board Diagnostics generations. The 92-95 Honda Civic (EG chassis) and Integra models are natively OBD1. OBD1 systems are earlier diagnostic systems, while OBD2 is a more advanced and standardized system mandated in the US starting in 1996. When performing an engine swap with a newer OBD2 engine into an older OBD1 chassis like the 95 EG Civic, compatibility issues arise primarily due to differences in engine management systems, wiring, and sensors.
However, Honda’s engineering foresight provides a degree of backward compatibility, especially within the Integra and Civic/Del Sol lines. This clever design allows us to utilize specific USDM (United States Domestic Market) OBD2 Integra parts to bridge the gap and make the 95 EG convert to OBD2 relatively straightforward. This guide focuses on leveraging these readily available parts to simplify your conversion process.
Essential Parts for Your 95 EG Convert to OBD2 Project
To successfully bolt an OBD2 B-series engine into your EG Civic, you’ll require a specific set of parts, primarily sourced from OBD2 Integras and certain OBD2 Civics. Note that ’94-95 Integra owners already have some of these components and can reuse them.
Here’s a comprehensive list of the necessary parts for your 95 EG convert to OBD2 project:
- Transmission Bracket (Front): Obtain a front transmission bracket from a ’94-01 Integra or ’99-00 Civic Si (any 5-speed model).
- Engine Bracket (Rear “L” Shaped): You’ll need the rear engine “L” shaped bracket from a ’94-01 Integra (any 5-speed model).
- Driver Side Engine Mount (3-Post): For B18B/C/C5 engine swaps, use a ’94-01 Integra driver’s side 3-post mount. Note: If you are installing an OBD2 B16A, you can reuse your existing Civic/Del Sol driver side dual-post mount.
- A/C Bracket: Source an A/C bracket from a ’94-01 Integra or ’99-00 Civic Si.
- Shift Linkage (Complete): A complete shift linkage from a ’94-01 Integra or ’99-00 Civic Si is required. Note: Del Sol owners must use a B-series Del Sol specific shift linkage, which may be harder to find used and is best purchased new from Honda.
- Axles with Half-Shaft (Complete): Use complete axles with half-shaft from a ’94-01 Integra or ’99-00 Civic Si.
- USDM ’96-01 Integra Engine Wire Harness: This is a critical component for your 95 EG convert to OBD2. The USDM ’96-01 Integra engine wire harness is designed to be backwards-compatible with OBD1 chassis, making the wiring integration significantly easier. Avoid JDM (Japanese Domestic Market) Integra harnesses as they are configured for right-hand drive vehicles and will not fit correctly.
- OBD1 ECU or OBD1-to-OBD2 Jumper Harness: You have two primary options for engine management, which will be discussed in detail below.
ECU and Wiring Strategies for 95 EG OBD2 Conversion
The engine wire harness is a key element in simplifying the 95 EG convert to OBD2 process. The USDM OBD2 Integra harness is designed in a two-piece configuration (breaking off at the shock towers), similar to OBD1 Civic/Integra harnesses. This two-piece design is what allows for the crucial backwards compatibility. Conversely, USDM OBD2 Civic harnesses are one-piece designs, making them incompatible with OBD1 chassis for this type of conversion.
When installing the OBD2 Integra harness, you will notice some plugs that do not connect to your OBD1 shock tower plugs. This is normal and will not hinder the engine’s operation.
VTEC and Sensor Wiring:
If you are upgrading to an OBD2 VTEC engine in a non-VTEC OBD1 Civic, you will need to manually wire in VTEC, the knock sensor, and IAB (Intake Air Bypass) for GSR/SiR-G engines. The wiring process for these components is the same as if you were installing an OBD1 VTEC engine, utilizing the same ECU pinout locations.
VTEC Pressure Switch (VTPS) Considerations for JDM OBD2 Engines:
JDM OBD2 engines often lack a VTEC Pressure Switch (VTPS). If you are using a JDM OBD2 engine, you’ll need to address this. You can either perform a simple wiring modification or swap the JDM VTEC Solenoid (VTS) for a USDM VTS.
VTPS Wiring Fix: Splice the power wire for the VTPS into the VTS wire and ground the VTPS ground wire to the VTEC Solenoid body. This resolves potential check engine lights (code 22) related to the VTPS when using a USDM OBD1 ECU that expects this sensor. If using a JDM OBD2 ECU, this fix is unnecessary as JDM ECUs do not monitor the VTPS.
ECU Options for Your 95 EG Convert to OBD2
You have two main options for ECU management after your 95 EG convert to OBD2:
1. Utilizing an OBD1 ECU (Recommended):
This is often the simpler and more cost-effective route. Simply use an OBD1 ECU that is appropriate for your OBD2 engine type. For example, for an OBD2 GSR engine, use an OBD1 GSR/P72 ECU. This ECU will plug directly into your existing OBD1 ECU plugs and manage the OBD2 engine effectively.
For engine types without a direct OBD1 ECU equivalent (like an OBD1 ITR ECU), you can use a reprogrammable OBD1 ECU, such as a chipped P28 ECU, tuned to match your engine specifications.
2. Employing an OBD2 ECU (Requires Jumper Harness):
If you prefer to use an OBD2 ECU, it is achievable but requires an OBD1-to-OBD2 jumper harness adapter. These adapters are available for both OBD2a and OBD2b ECU types.
USDM OBD2 ECU Considerations: If you opt for a USDM OBD2 ECU, you will need to wire in a secondary O2 sensor and perform the CKF (Crankshaft Fluctuation Sensor) fix. These are necessary because USDM OBD2 ECUs monitor these sensors, which were not present in OBD1 systems.
JDM OBD2 ECU Advantages: JDM OBD2 ECUs do not require a secondary O2 sensor or CKF sensor wiring, simplifying the installation if you choose this ECU route.
Conclusion: Your 95 EG OBD2 Conversion is Within Reach
Converting your 95 EG Civic to OBD2 for a newer B-series engine swap is a popular and manageable project. By utilizing the correct USDM OBD2 Integra parts, particularly the engine harness, and understanding your ECU options, you can achieve a successful and reliable conversion. Whether you choose the simplicity of an OBD1 ECU or the more complex OBD2 ECU route, this guide provides the essential information to navigate your 95 EG convert to OBD2 project with confidence. Remember to always prioritize safety and consult reliable resources and experienced professionals when undertaking automotive modifications.
