Setnev Posted December 8, 2016 Share Posted December 8, 2016 Well guys after weeks of combing through wiring diagrams and creating endless spreadsheets, I believe I have found a way to convert your 99 EJ25 harness to accept a EJ222, or EJ222 top end. Instead of pulling the whole harness out from behind the dash and replacing it with the EJ222 harness, I am working on converting the harness with very minimal changes to the EJ25 harness. The harness, for the most part, is 90% the same. Best part about it is, I am working on a plug-in conversion kit so you can go back and forth between a EJ25 and EJ222 ECU and electronics with no further modification More details to follow! :spin: Disclaimer: The reason I am doing this is because I got a mid-90's EJ25 bottom end for free and have a perfectly good EJ222. I am combining the EJ25 bottom end and EJ222 top end for a higher compression engine that is ECU friendly. The downside is that you must use the EJ222 ECU and engine harness. Those of you that know about the 99 know it is a rare breed in terms of electronics. Link to comment Share on other sites More sharing options...
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