Hey guys, I've got an 89 Turbo II. I ordered an engine a while back and received an S4.... Anyway, I threw it into the car and it won't start now.... I've replaced pretty much everything fuel related on the car. I replaced the turbo system with my old S5 one. I left the mechanical OMP, the intake manifolds, and most of the other stuff on the new S4 motor alone.

I've come to find out that the S5 ECU won't allow the car to run normal without switching over the OMP, and possibly more. Can I just switch the little OMP thing, or do I have to switch the whole front cover + internals over? Can I just run a S4 ECU and harness instead of doing all that swapping? Or will the dash harness or whatever not plug into an S4 ECU?

Basically, what's the easiest route to go? I've been working on this damn swap for a year and a half (winters in Wisconsin with no garage doesn't allow me to do much). I don't really have the money to go standalone yet... The old S5 motor's been sitting outside for a good while and most of it's parts aren't too good I'm guessing. So, any good advice?

 

dash harness will not plug into the engine harness or ECU. I made the same mistake except i got an S5 engine/tran with and s4 chasis. I bought an s5 TII clip and am keeping the orig eng as a spare

 

You have to switch the whole front cover. This should've been done before putting the eninge in. Even better would've been to get the right engine (an S5 one), so that you avoid all this drama and you aren't downgrading.

That would be much more work than swapping the front cover. Way too many differences.