has any body done this before the wires of the ecu are not alike what can i do i have all the 91 set up and i cant return it please help

 

You need to get an s5 ecu and wiring harness. The s4 won't work because there is alot more stuff the s5 ecu controls. Ex: The Oil Metering Pump (OMP) on the s4 is mechanically controlled where on the s5 it is controlled by the computer.

 

i have a 91 mazda rx7 that i use for parts so i have to swap the wireing that goes under the dash board

 

You need to get your hands on both the 1986 - 1988 and 1989 - 1991 FSM's so you know what the wire colors are on the both sides of the plugs.
It's a matter of connecting the matching wires.


-Ted