Converting your B series engine from OBD2 to OBD1 is a modification often considered for performance tuning or when dealing with engine swaps. This process involves changing your engine management system to an older, but in some cases, more tunable standard. Here’s what you need to know about performing an OBD2 to OBD1 conversion on your B series engine.
Understanding OBD Systems: OBD2 vs OBD1
OBD, or On-Board Diagnostics, is a standardized system used for vehicle self-diagnostics and reporting. OBD2 is a more advanced system compared to OBD1, offering enhanced diagnostics and emissions monitoring. However, for certain enthusiasts, OBD1 ECUs are favored for their simpler architecture and perceived ease of tuning, particularly in older Honda and Acura models with B series engines.
Performing the OBD2 to OBD1 Conversion on a B Series Engine
When converting from OBD2 to OBD1 in a B series engine, several key aspects need to be addressed to ensure a smooth and functional transition.
Harness Compatibility and Wiring
A conversion harness is typically used to adapt the OBD2 wiring in your vehicle to accommodate an OBD1 ECU. These harnesses are generally plug-and-play, simplifying the wiring process. However, there might be specific considerations depending on your vehicle and engine configuration.
For example, if you are using a Honda HX model, it’s often necessary to convert to a 4-wire oxygen sensor setup. This is a specific wiring modification required in some cases. For the secondary oxygen sensor, in most OBD2 to OBD1 conversions, it is not necessary to remove or rewire it. Many users have reported successfully running their converted systems with the secondary O2 sensor plugged in without adverse effects. Basic plug and play harnesses usually handle most of the conversion without extensive rewiring, aside from specific cases like the O2 sensor mentioned.
ECU Requirements
One of the fundamental changes in this conversion is the Engine Control Unit (ECU). You cannot use your original OBD2 ECU with an OBD1 conversion. The ECUs are not plug-compatible and operate on different communication protocols. The primary reason for undertaking an OBD2 to OBD1 conversion is often to utilize an OBD1 ECU, which offers different tuning capabilities.
If you have a non-VTEC engine, you will need to ensure you use a non-VTEC OBD1 ECU. The ECU must be compatible with your engine type (VTEC or non-VTEC) and be designed for OBD1 systems to function correctly after the conversion.
Conclusion
Converting your B series engine from OBD2 to OBD1 is a process primarily driven by the desire for specific ECU tuning capabilities or compatibility needs during engine swaps. While conversion harnesses simplify the process, understanding the nuances of wiring, particularly concerning oxygen sensors, and the necessity of swapping to an OBD1 ECU is crucial for a successful conversion. Ensure you choose the correct OBD1 ECU for your engine configuration to achieve optimal performance after the conversion.
