Some time ago I attempted to apply this patch - How to control closed loop afr - to my rom (evo 9), followed the instructions changing the values/addresses for the new tables in the rom and I was unable to get it to work. I ended up giving up on it so I scrapped the patched xml and rom and flashed back to a stock evo 9 88590015 xml and rom. Later I realized I couldn't get it to work because my mut table was messed up (mut table is now fixed) so the addresses used by the patch didn't match up with the mut table.

My question is this: If I flashed my ecu with the xml and rom containing the patch (new values/addresses in new tables for the patch), then flashed it back to a stock 88590015 xml and rom, do the previous changes made to those patch tables in the rom still exist in the ecu even though I no longer see the patch tables defined since I removed the patch from the xml file? Do I need to change the values/addresses in the new patch tables back to stock values/addresses before removing the patch tables and flashing back to a stock xml and rom?

 

If you flashed back to the stock evo 9 map, it should have removed any patches/.xml edits and the car should behave like it would have from Mitsu. ECU flash supposedly detects the differences between the tune you are loading and the tune that is on the car, then corrects all the differences. From a memory perspective, that new closed loop patch data could still be defined in the ecu memory somewhere, but the stock xml and rom should not be looking for it or using it to run the engine.

 

Good to know, that's what I was hoping for. I was wondering about this because I've been dealing with a weird inconsistent afr issue for so long now with no luck on figuring it out.
My thread about it here: Afr issue
I've replaced front o2, wideband, boost leak tests, flashed stock rom, deleted egr stuff and added new vacuum lines to everything etc. I'm stumped