Here I will help you out a little.
http://www.ka24development.com/cwilf...lectrical.html
You will need the correct ECU for a 1997- 1998 that is an MT.
There is the way the wiring should be when a manual ECU is connected. However the step where he says don't connect is false if you use a manual ECU. I connected it and no more CEL, however I would cross reference your wire pin out on the on the ECU to make sure you have the correct wires lol especially since you are cutting into your factory harness. If you can get ahold of an Factory service manual (FSM) for a 1998 240sx it will be you best friend for any other repair you may need to tackle.