i have a honda civic automatic with a 1.6 vtec engine engine went bad and my dad had a D15B7 hanging around so he dropped it in to save me money. car now has an up and down RMP issue (mostly when you first start giving it gas) nether engine did this prior to swap. he then changed out all engine parts back and forth on the two engines to see if any part was bad but it keeps doing it. so we assumed it just needed an ECU that is for the 1.5, so i bought a used one, swapped that and still the same thing! can it be that i need to change out the wire harness too? or any other things you might know it possibly could be? any help would be great!