The P28 ECU is a popular choice in the Honda tuning and engine swap community. Often discussed in the context of OBD2 conversions, it’s essential to understand what a P28 ECU actually is and why it’s relevant when talking about “P28 Obd2” upgrades.
The original forum post highlights a common scenario: swapping a D15B engine, which typically uses an OBD1 ECU, into a Honda originally equipped with an OBD2 ECU like the P2E. The P2E is a non-VTEC OBD2 ECU, whereas the D15B often pairs with a P08, an OBD1 VTEC ECU. This is where the P28 ECU comes into play.
The P28 ECU itself is an OBD1 ECU, not OBD2. It became a favorite for Honda enthusiasts because it’s a tunable OBD1 ECU that supports VTEC and is relatively easy to find and modify. When people search for “p28 obd2”, they are usually encountering situations where they have an OBD2 vehicle and need to use an OBD1 ECU like the P28 for engine management, especially after an engine swap or when planning for performance tuning.
To use a P28 OBD1 ECU in an OBD2 Honda, you will need a conversion harness. This harness bridges the wiring differences between the OBD2 car and the OBD1 ECU. The original post correctly points out the need for this conversion harness and the importance of identifying whether your original ECU setup is OBD2A or OBD2B.
To determine if you have OBD2A or OBD2B, you need to look at your ECU connectors.
OBD2A ECUs typically have all three connectors grouped closely together.
OBD2B ECUs are characterized by a space between the middle and right connectors. Knowing this distinction is crucial when purchasing the correct OBD2 to OBD1 conversion harness for your “p28 obd2” project.
While a P08 OBD1 ECU could be used with a D15B for a basic swap, the P28 is generally recommended, especially if you anticipate any future modifications or tuning. The P28 offers more flexibility and tuning capabilities compared to the stock P08.
In summary, when considering “p28 obd2”, remember that the P28 is an OBD1 ECU. The term usually refers to the process of using a P28 in an OBD2 vehicle, requiring an OBD2 to OBD1 conversion harness. This setup is popular for engine swaps and for those looking to tune their Honda engines, leveraging the P28’s tuning capabilities. Understanding your OBD2 system (A or B) is the first step in a successful P28 conversion.
