WILL A ECU Z4 OUT OF THE WRX SUBARU GO IN TO MY UK SPEC SUBARU WITH OUT ANY TROUBLE IS IT A STRAIGHT PLUG AND PLAY?

 

Its not compatable in some cases and why would you want to change anyway?
Upto and including 1996 the uk cars ran a TD05 turbo, from 97 onwards they ran a smaller td04 turbo, the early wrx's ran a TD05 turbo and the fuel map was for 100 ron fuel, the uk fuel map was for 95 ron fuel.
The differences in the fuel could have serious mechanical consequences to your engine, if you still wish to try to replace a uk spec ecu with a jdm one, have a go, it if blows up leaving you with a repair bill of around 2500 quid dont say I didnt warn you.

Tony

 

just get an FC and done with it mate

 

As long as he used 100 RON fuel in the UK car with the z4 i dont see a problem and vice versa, if he puts the uk ECU in the wrx he can quite happily run 95 ron.

 

He should be OK if he runs Optimax as the Z4 map was what Prodrive based their PPP ECU on.

And wasn't it late 90's that Jap fuel was changed to 100RON, before that it was lower IIRC.

 

Both of the above statements are correct.