So clarify what "it worked fine" means? Does that mean that the engine runs more or less the same on A & B after the copy? Or does that simply mean that you know the data copied OK?

Mike;

Tune A; copy to B – if the copy is successful it should then run the same on B as A.  The only difference (TIAAO) is A has induction air temp input and B doesn’t. It is a second order effect, and if running at about the same OAT there should be no difference.

If it is copying successfully, then it seems it is at least remotely possible that there is something amiss with the inlet air temp sensor causing the tuning of A to be biased. You can measure its resistance, and unless, again, something is different than on my controller; it should be about 10K Ohms.

Al