For Honda enthusiasts looking to boost the performance of their OBD1 vehicles, the P72 ECU from the Integra GSR is a popular and effective upgrade. This guide explores the best approaches to integrate a P72 Ecu Obd2 into your OBD1 Honda, simplifying the process and maximizing results without unnecessary complexity.
Understanding the P72 ECU and OBD2 Compatibility
The P72 ECU, originally found in USDM OBD2 Integra GSR models, is highly sought after for its enhanced fuel and ignition maps compared to standard OBD1 ECUs in Civics and Integras. While your older Honda might be running on an OBD1 system, utilizing a P72 ECU opens up tuning potential and performance gains. The key is understanding how to bridge the gap between OBD2 components like the P72 ECU and your OBD1 vehicle’s wiring.
Simplified P72 ECU Installation with an OBD2 Integra Harness
One straightforward method to install a P72 ECU is by leveraging an OBD2 USDM Integra engine harness. This approach eliminates the need for extensive wiring modifications or adapter harnesses, streamlining the swap and saving time. Unlike OBD2 Civic harnesses, Integra harnesses are designed in two pieces with strut tower plugs, similar to OBD1 setups. This crucial difference allows for a more direct integration into your OBD1 Civic. JDM harnesses should be avoided due to right-hand drive configurations and potential damage.
By using an OBD2 Integra harness, you maintain plug-and-play compatibility for essential engine components such as the alternator, injectors, and distributor. Forget the outdated methods of swapping OBD1 parts or intricate splicing into OBD2 harnesses – these approaches introduce unnecessary complexity and potential wiring headaches. The OBD2 Integra harness directly interfaces with your OBD1 Civic harness at the strut towers, requiring minimal additional steps. You will encounter a spare plug on the OBD2 harness, which can simply be secured out of the way.
At this stage, you have several options for ECU management, each with its own advantages and considerations:
Option 1: OBD1 USDM Manual P72 ECU
Plugging an OBD1 USDM manual P72 ECU into your Civic ECU harness is a traditional method. This requires adding pins to your ECU harness for features like knock sensor, IABs (Intake Air Bypass System), and VTEC (Variable Valve Timing and Lift Electronic Control), and running the corresponding wires to the engine. While historically popular, OBD1 manual P72 ECUs are becoming harder to find and often command a higher price.
Option 2: OBD1 Automatic P72 ECU Conversion
Similar to Option 1, but utilizing a more readily available and cheaper OBD1 automatic P72 ECU. Converting an automatic P72 ECU to manual operation is a manageable process, making this a cost-effective alternative to sourcing a manual version directly.
Option 3: Chipped P06/P28 ECU with B18C1 Tune
Consider using a P06 or P28 ECU, chipping it, and flashing it with a B18C1 tune (the engine code for the Integra GSR). This option allows for custom dyno tuning, maximizing performance gains. Modifications to the circuit board are necessary to incorporate IABs and VTEC (though P28 already supports VTEC). While Options 1 and 2 ECUs can also be chipped and tuned, starting with a P06/P28 can be a more budget-friendly approach if custom tuning is your goal.
Option 4: OBD2 Manual P72 ECU with OBD1 to OBD2 Conversion Harness
Employing an OBD2 manual P72 ECU in conjunction with an OBD1 to OBD2 conversion harness offers a balance of cost and availability. OBD2 P72 ECUs are generally more affordable and easier to locate than their OBD1 counterparts. Conversion harnesses, while less common than standard harnesses, are readily obtainable from suppliers like Rywire. This setup necessitates bypassing the CKF (Crankshaft Fluctuation Sensor) and wiring in a knock sensor, straightforward procedures for experienced DIYers. Additionally, a secondary O2 sensor bung downstream of the catalytic converter will be required. This option is often considered a legitimate and emissions-compliant approach in many regions.
Option 5: JDM OBD2 P72 ECU with OBD1 to JDM OBD2 Conversion Harness
Utilizing a JDM OBD2 P72 ECU with a JDM-specific conversion harness can be the most economical and easiest route. However, it’s crucial to note that this option may not meet emissions standards in certain areas, such as California’s BAR (Bureau of Automotive Repair) program. For street-legal applications in stricter regions, Options 1, 2, and 4 are generally more suitable, with Option 4 often being the most legally compliant.
OBD2 ECU and Harness
Alt Text: OBD2 P72 ECU upgrade with Integra harness for Honda OBD1 vehicles, showcasing compatibility and modification options.
Conclusion
Upgrading to a P72 ECU for your OBD1 Honda is a worthwhile modification to unlock performance potential. While several paths exist, utilizing an OBD2 Integra engine harness simplifies the installation process significantly. Alternatively, pairing an OBD2 P72 ECU with a conversion harness offers a readily available and cost-effective solution. Carefully consider your tuning goals, budget, and local emissions regulations when selecting the optimal P72 ECU integration method for your project.
