But again, you keep asking "why" when you kind of answered it yourself. You deleted the IMRC's, you need a retune for those typically. If a new head unit has been swapped on and is running a tune that was meant for another one, you need a retune.
Not sure why a built motor had IMRC's still either, people usually delete those.
Not sure why a built motor had IMRC's still either, people usually delete those.