So I have both complete cars. I know I need to swap the motor,drivetrain,harness and ecu. But I noticed the pinouts on the ecus are different on the far right plug connector. Do I need to swap out the dash wiring/instruments for this swap? Also are there any other things that I should know that are specific to this swap? Thanks in advance

 

you might be better off using the S5 wiring and ECU and changing the front cover/MOP and a few other things to make the ECU and wiring think that it is a S5 motor

 

It's more work than it's worth, either change the harnesses behind the dash, or change just about everything on the block.

Edit: Reason's why it won't be easy to do with ECU swap or engine to s5.

1) harnesses are all different
2) s5 has electric omp
3) dual tps
4) oil lines are different between s4 & s5 (front covers are different so they're located in different spots, though the s5 N/A would have to be drilled out regardless)
5) wrong injector clips
6) s5 tII ecu required (n37x)
7) s5 pressure sensor required (n37x)
8) have to rig up the knock sensor
9) alternators are different
10) s5 TII AFM

And so on and so on. The easiest way to go about it, is obviously swapping the harnesses, but that's not easy by any means either

 

well I have both harnesses pulled through the firewall and sitting on the motors, so I dont have to finagle with the clips on the motors. correct me if I am wrong but behind the dash there are only 2 large bundles to worry about...right? So I need to swap the guage cluster and dummy lights too right? Would it be easier to keep the bundles clipped to the underside of the ser4 dash and just swap the whole dash in? thanks Again.

 

up

 

Easier said than done. And most of the harnesses that branch from that aren't interchangable, so it becomes quite a pain in the *** to do.

 

any more input?