For Honda and Acura enthusiasts, engine swaps and ECU tuning are common paths to performance enhancement. Navigating the world of Honda ECUs can sometimes feel like deciphering a secret code, especially when encountering ECUs like the P9K. A frequent question arises when dealing with these ECUs, particularly in the context of older OBD1 systems and the newer OBD2: Is the P28 Ecu Obd1 Or Obd2, and how does it relate to the P9K ECU, especially when considering OBD1 to OBD2 swaps?
This article will clarify the OBD status of the P28 ECU and shed light on its compatibility with systems that might seem OBD1 or OBD2, like those using the P9K ECU. We’ll address the connector styles, internal electronics, and practical implications for your Honda tuning projects.
To understand this better, let’s first address the confusion that often arises from visual inspection. The P9K ECU, commonly found in European Honda Civic MB6 models with the B18C4 engine, presents a unique challenge. At first glance, its connector resembles the older OBD1 style.
However, appearances can be deceiving. Despite the OBD1-style connector, the P9K ECU is actually an OBD2 system internally. This means it uses the more advanced OBD2 protocols for diagnostics and engine management. This discrepancy between connector style and internal electronics is the root of the confusion.
So, where does the P28 ECU fit into this picture? The P28 ECU is a well-known and highly versatile OBD1 ECU, popular for tuning and engine swaps in older Honda vehicles. It’s commonly used with engines like the B16A, B18C1, and B18B when running an OBD1 system.
Now, the interesting part is the compatibility between these seemingly different ECUs. Experienced Honda tuners have discovered that the P9K ECU, despite being OBD2 internally and having an OBD1 style connector, can be replaced with an OBD1 P28 ECU. This is possible due to the pinout similarity between the P9K and OBD1 ECUs.
The key to using a P28 ECU with a system originally designed for a P9K (like the B18C4 in a European Civic MB6) lies in a minor modification: trimming two plastic tabs on the P28 ECU connector. This simple modification allows the OBD1 P28 ECU connectors to physically fit into the P9K wiring harness.
It’s crucial to understand that while the connectors become compatible with this modification, you should always double-check the pinouts to ensure correct wiring. While many pins are in the same positions, the numbering convention can differ between P9K and P28 ECUs (P9K is left-to-right 1, 2, 3, 4…, while P28 can be odd/even numbered). However, users have reported successful swaps without rewiring, indicating a high degree of pin compatibility.
In conclusion, while the P28 ECU is definitively an OBD1 ECU, and the P9K ECU is internally OBD2 with an OBD1 style connector, they can beinterchanged with a simple connector modification. This makes the P28 ECU a viable and popular option for tuning and managing engines that originally came with a P9K ECU. For those looking to simplify their engine management or leverage the tuning capabilities of the P28, this compatibility offers a practical and effective solution. Always proceed with caution and verify information when undertaking ECU modifications and swaps to ensure the best results for your vehicle.
