[boxcaracer182]

I'm about to start spark plugs but was wondering is there any way other than marking the DME yourself to tell which one goes to which cylinder bank when you remove them?

[pbonsalb]

My recollection is that they are not identical and that mixing them up should not be a concern, but I have had mine out only twice and the last time was a year ago so maybe my memory is wrong.

[nick380]

According to realoem, they are the same DME on both sides. Which makes sense. Best to just mark with paint marker or sharpie "M" and "S" for master and slave just to be safe. Doesn't harm it.

Master is on passenger side, slave on driver side. If left-hand drive.

[pbonsalb]

I think I was confusing the passenger side ECUs where 1 is for the engine and 1 is for the trans. Maybe the two engine ECU are the same, but they are so far apart that it is unlikely you would mix them up. I do the plugs one side at a time, for example, and have never had the slightest concern about mixing them up.

If I was doing a bigger job where I had everything off the top of the motor and had to pile it up somewhere, I would mark them. Can’t hurt to mark them. I will be doing a big job soon — Supersprint turbo headers, but am hoping I won’t have to pull the ECU since I will be working in the center of the Vee rather than on top of the heads.