Rebuilding my Turbo II its an S4. Is there an benefits from using an S5 ECU rather than an S4 ECU?

 

You can't use an S5 ECU in an S4 car without completely swapping wiring and engine sensors (TPS, AFM, MAP, etc...). The plugs are different shapes, wires are not in the same locations, some wires don't exist, and sensor outputs are not the same.

 

I am switching the engine and dash harness if i do it i was just wondering if there are any benefits from using an S5 ECU then an S4 ECU

 

There are mainly minor differences, and one big negative. Nothing worth wasting lots of time and money converting the Front harness, EM harness and more to S5. Just to name a few of the larger changes:

1) Timing will be slightly more retarded since S5s used 9.0:1 CR rotors
2) Knock control is integrated, so no knock box needed
3) The ECU has more control over idle, but the variable resistor was removed
4) Electric MOP/OMP will be needed or the ECU will go into limp mode.

 

Cool thanks man