tuned-civ

hello i have a question witch is prob retarded but here it is..

i got a 92 civic si parts car has the d16z6 motor and the p28 ecu i think. im driving around a 95 vx with idk wat ecu but w.e i wanna put the d16z6 motor into the vx but when i looked at the wire harness the si harness only has a 4 wire o2 sensor and the vx has a 5 wire o2 sensor cant find anything else different bout the harness.. now when i do this swap am i gunna have a check engine light and will the ecu plug right in and will i have any problems with the motor/ecu or anything or will it be a clean perfect swap.. j.w cuz i feel liek htis motor is on the way out in the next few days so if someone could get back that would be awsome and i would really appriciate it.. thanx