okay heres the problem

i have a 1990 integra ls and ever since i got the car the rev limiter has kicked in at 5700 rpms. now i had a 1991 integra ls ecu with no rev limiter or speed govenor in my old car. i swapped ecu's and it still redlines at 5700. the ecu isnt throwing any codes what so ever and i dont know what is wrong with it. i thought that the rev limiter was all in the ecu. i always changed throttle bodies around too and it still limits it at 5700. Can anyone help me out and tell me what the expletive is wrong with my car