That looks like the standard test and not the adjust. My manual didn't match what was actually in the ROM for tests. It was as if they added a new engine test/adjust in a later ROM maybe?
The ammendment describes the new test as T.18 but in the manual T.18 is Empty Balls:
http://mirror2.ipdb.org/files/570/Bally_1994_Corvette_Manual_Amendment_16_9890.pdf
The standard engine test should be T.16 if I remember right.