This guide provides detailed instructions for converting an OBD2 Integra (96-01) to an OBD1 distributor. This conversion is popular for engine swaps and performance tuning, offering more flexibility with engine management systems. We’ll cover the necessary parts, wiring modifications, and ECU options for a successful conversion.
Understanding OBD1 and OBD2 Systems
Before diving into the conversion, it’s crucial to understand the key differences between OBD1 and OBD2 systems:
- OBD1 (On-Board Diagnostics 1): Utilized in vehicles manufactured before 1996. Features a simpler engine management system with less stringent emissions regulations. Often preferred for aftermarket tuning due to its adaptability.
- OBD2 (On-Board Diagnostics 2): Implemented in vehicles from 1996 onwards. Incorporates more sophisticated sensors and computer controls for improved emissions monitoring and diagnostics.
Distributor Compatibility and Modifications
The primary component in this conversion is the distributor. OBD1 and OBD2 distributors have different connectors and internal components. Here’s a breakdown of the options:
- Using an OBD1 Distributor: This requires modifying the engine wiring harness to accommodate the OBD1 distributor plug. This involves splicing and connecting the correct wires based on a wiring diagram.
- Using an OBD2 B-Series VTEC Distributor: A simpler approach is to use an OBD2 distributor from a 96-00 B-series VTEC engine. This distributor is often plug-and-play with a 96-98 Integra engine harness, eliminating the need for splicing.
Wiring Harness Considerations
The engine wiring harness plays a vital role in this conversion. Here’s what you need to know:
- Integra’s 2-Piece Harness: 96-01 Integras utilize a 2-piece wiring harness design, making them compatible with OBD1 engine harnesses. This significantly simplifies the conversion process.
- OBD1 Engine Harness Compatibility: You can use an OBD1 VTEC engine harness from a 94-95 Integra GSR, 92-95 Civic Si/EX, or 93-95 Del Sol VTEC. Ensure VTPS, VTS, and Knock Sensor wiring is present if using a non-VTEC Integra.
ECU Options and Considerations
Choosing the right ECU is crucial for proper engine operation after the conversion. Here are the common options:
- JDM OBD2 ECU: This option offers a direct plug-and-play solution for 96-99 Integras. However, JDM ECUs may have speed limiters and might not be compatible with US OBD2 diagnostic tools. Passing emissions tests can also be a concern.
- OBD1 ECU Conversion: Converting to an OBD1 ECU (like a chipped P28) provides extensive tuning capabilities. This requires an OBD2a to OBD1 jumper harness. You’ll need to wire in a VTPS. Emissions compliance will not be possible with this setup.
- US OBD2 ECU: Using a USDM OBD2 ECU allows for potential emissions compliance. However, this requires addressing the Crank Fluctuation (CKF) sensor issue, as OBD1 engines lack this sensor. A CKF bypass trick is often implemented to overcome this. A second O2 sensor may need to be wired in.
Additional Wiring Modifications
Beyond the distributor and ECU, several other wiring adjustments might be necessary:
- Injector Clips: Convert to OBD1 injector clips or use OBD2 injectors for plug-and-play compatibility.
- Alternator Plug: Use an OBD1 alternator plug or an OBD2 B-series alternator for a direct fit.
- IAT Sensor: Adapt the OBD1 IAT sensor or modify the intake to accommodate the OBD2 sensor.
Conclusion
Converting an Integra from OBD2 to OBD1 distributor involves several key steps, including selecting the appropriate distributor, modifying the wiring harness, and choosing a compatible ECU. Each option presents its own set of advantages and challenges regarding performance, tunability, and emissions compliance. Thorough research and careful execution are essential for a successful conversion. Consult detailed wiring diagrams and consider professional assistance if needed.
