OBD1 Code Compatibility

OBD1 Civic Integra ECUs are a common hardware platform.

What this means is that you can (with minor modifications) run essentially any code on any ECU in the family. There are rules however:

• Vtec programs (P28, P30, P72, ...) require a Vtec ECU or a Non Vtec-To-Vtec conversion.
• Non-Vtec programs run in a Vtec ECU without any problems.
• Vtec programs run in non-Vtec ECUs with vtec disabled. (DB: they may even work with vtec xover above redline although I think the sensor checks for VTP/VTS will cause issues.)
• 1-wire O2 ECUs like P05, P08 require either One Wire To4 Wire O2 Sensor conversion of the hardware or to disable the O2 Heater Circuit in the ROM.
• DOHC Vtec programs (P30, P72, ...) generally have a Knock Sensor enabled. To use these programs on ECUs lacking the Knock Board (P28, P08, conversions, ...) you must first disable the Knock Sensor.

For information on disabling Knock Sensor or the O2 Heater Circuit in software, please consult the Rom Maps for the code you are working with.

Additionally, different markets received different features in their ECUs.

• USDM ECUs are by far the most full-featured. Almost any code will run in a USDM ECU if the above rules are followed.
• JDM ECUs generally lack several things that must either be physically added to the ECU or disabled in the ROM. The Pressure Atmosphere (PA) sensor Electrical Load Detector (ELD) and Injector Test Circuit are the most notable things here.
• EDM ECUs are generally the most bare. They generally lack PA, ELD, Injector test like the JDM ECUs, and will occaisonally lack the Knock Sensor and knock board present in JDM ECUs too.