Originally Posted by OhioYJ

From what I've read on hear in some states they just plugg into the OBD II port and check for codes if none are present and ECU is in a "ready" state. This ensures someone hasn't cleared codes just before the check station to pass the test, as the car has to be driven some to be considered ready. With a tune you can have certain codes disabled, like for cats, which is fairly common, on these cars. It is my understanding that disabling these codes will make the cars fail some of these tests. Out of curiosity I've been meaning to hook up my OBD II scanner to my car and see if shows ready across everything or not, but since we don't have emissions testing in my area, not a big deal for me. (I do have cats, just HFC) So if you gave codes disabled that maybe what's stopping you there.

Didn't the original owner mention harness changes with that ECU? If there were, that may mean a stock ECU will not be plug and play.