I bought a p28 ecu for my 2000 gsr swap, and the ecu came socketed, it had no chip in it, so it was in limp mode and wouldn’t rev beyond 4000, I just bought and installed a mugen chip, and it now revs all they way it should, but at idle it keeps reving to about 2-2.5 k and just goes up and down.
Is there a reason that it is doing this?