alright, i just finished transplanting a 91 s5 motor, engine harness, and ecu into my 87 s4 rx7. Basicaly i adapted the dash harness to work with the s5 ecu( cut the s5 connector off and spliced s4 wires ito it). but i have a couple of problems. firstly i have no injector pulse but good spark fireing and fuel pressure. and secondly i get only very few warning lights coming on (doors, hatch, belts, and brake). anyone have any ideas that might remidy any of these problems. i know there are only a few if any people that have done this swap.

 

Wow that was the wrong way to do it. If it was possible you should have keept all the s4 external engine parts and swapped them over. The s5 ecu has many more inputs that the s4 some of your gauges arent goin to work. The fuel pump relay is going to be differnt because the s4 turns on by the switch. you would have probably been better off splicing the s5 harness into your s4 ecu. Also there is a starter lock switch on the s4 and i dont believe the 89 has that. I hope you got the wiring diagram for the s5 cause your gonna need it.

 

also did you splice the fem-01 and fem-02 connectors. those are the brown colored ones that go from the emissoin harness to the front.

 

how did u do ur fuel pump wiring?did u run jus the power and ground switch off the large plugs u also have to run one of the wires from fem 1 to the body plug from the dash.

 

well basicaly i kept the original s4 body and dash harness and ran the s5 engine, accessories, engine harness, and ecu.

 

sorry to go off on my own, but Rudeboy, i am having troubles with my fuel pump i think. It starts and runs for like 5 seconds then shuts down. I didnt do any special wiring to my fuel pump i just hooked up the s4 wire into what would be the wire comming from the s5. Is there something else

 

you should not do that dude, because the s5 wire from the ecu is for the resistor relay and the s4 did not have one. just keep the original s4 wireing to the pump.