Many enthusiasts performing engine swaps encounter unique challenges, and one common hurdle involves electronic control unit (ECU) compatibility, especially when dealing with older vehicles like a 1997 Acura Integra and incorporating components from different models. If you’re facing a frustrating 6000 RPM rev limit after swapping a J32A2 engine and 6-speed manual transmission from an Acura CL into your 97 Integra, understanding the role of the 97 Acura Cl Obd2 Port and ECU is crucial.
Understanding the 6k RPM Rev Limit Issue Post-Swap
The problem, as described, is a distinct 6000 RPM limit encountered after a J32A2 engine swap into a 97 OBD2a Integra. This setup utilizes a 6-speed manual transmission, presumably from a CL-S model, but is currently running with a PGE automatic ECU, initially a rusty P6E ECU was also tested. The engine runs well up to this point, indicating basic functionality, but the inability to rev beyond 6k RPM is a significant performance bottleneck. This issue immediately points towards potential limitations imposed by the ECU, particularly when mismatched with the manual transmission setup.
ECU Compatibility and the OBD2 System in Older Acura Models
The OBD2 port in your 1997 Acura Integra is the gateway to your car’s computer system, allowing for diagnostics and communication with the ECU. However, ECU programming and compatibility are not universal, especially when mixing components across different Acura models and transmission types. An automatic ECU, like the PGE, is programmed with parameters specific to an automatic transmission. These parameters include shift points, torque converter lockup, and potentially, rev limits that are different from those in a manual transmission vehicle.
The original forum post highlights a critical point: using a CL-S6 transmission (manual) ideally requires a CL-S6 ECU to properly interpret signals, such as the transmission side crank sensor. An automatic ECU might not fully recognize or utilize all the inputs from a manual transmission, leading to operational limitations, such as the 6k RPM rev limit.
Exploring Solutions: ECU and Wiring Considerations
The idea of wiring in a CL-S shifter to “trick” the automatic ECU into thinking it’s in drive is a creative approach, but it’s unlikely to fully resolve the fundamental incompatibility. While it might potentially bypass some safety checks related to gear selection, it doesn’t fundamentally alter the ECU’s programming, which is designed for an automatic transmission. The rev limit is likely embedded within the ECU’s fuel and ignition maps, which are calibrated for an automatic, not a high-revving manual transmission setup.
A more direct and effective solution would be to consider using a manual transmission ECU appropriate for the J32A2 engine and 6-speed transmission combination. While factory manual transmission ECUs might be more expensive, they are programmed to properly manage the engine’s performance characteristics in a manual transmission vehicle, including VTEC engagement and higher RPM ranges.
Referring to the Acura CL service manual, as suggested in the original post, is an excellent step. This manual will provide detailed wiring diagrams and ECU specifications, helping to understand the differences between automatic and manual ECU setups and identify the correct ECU part number for a manual J32A2 CL-S.
In conclusion, while the 97 Acura CL OBD2 port is essential for diagnostics, the 6k RPM rev limit issue in your Integra swap strongly suggests an ECU incompatibility problem. Focusing on acquiring and properly wiring a manual transmission ECU designed for the J32A2 and 6-speed setup is the most likely path to unlocking the full potential of your swapped engine and resolving the rev limit. Exploring wiring diagrams and service manuals will be crucial in ensuring a successful and properly functioning swap.
