Not completely sure need lots of help.
 

I'm getting ready to start swapping a S4 TII in my S5 N/A and I want to keep the N/A harness when I do it. I need to know what wires/sensors/plug-ins need to be changed or modified to make work. Also I'm going to do a compression check on it before I put it in and wanted to know also what numbers I am looking for?

you might have an issue with injector resistance issues , i recently swapped a s4 87 t2 motor into my friends vert and we could run the motor with the injectors but he would have some weird fuel leaning issues. the injectors were center tabs instead of off center, but for the most part you only have to extend the tps wires from the na harness, dont quote me on this because im not entirely postitive on the s5 wire harness other than you will have to change injector clips and you might possibly have to wire inline some resistors , but what year did your motor come out of i think in 88 they switched to the s5 style impedace injectors but used a different style clip,. you might be able to just swap in the s4 harness to use with your s4 t2 ecu, but like i sayd im not sure if itll work with the s5 ignition harness, but could have just been the vert harness, we had a problem with a perfectly good s4 t2 harness.

Ok thanks a lot. I think the motor came from an 88 but I'm not positive. I don't have the harness and ecu because the guy i bought it from hacked up the harness taking it out and didn't get the ECU haha so that isn't an option haha.

did you get the mass airflow sensor? if not you cant run it period. and you have to have the turbo ecu, or an 88 convertable ecu(for some reason they can run turbo. but you will hopefully be in luck with the fact that you might only have to change injector clips but not have to use resistors in line. did u get the trans too??? if not your gunna have some other issues, some people agree that you can just use na flywheel with counter weight, butothers say the weight still wont be a properly balanced rotating assembly, im not going to choose sides(avoid argument) if you did get the tranny either you need a madzdatrix driveshaft to go from t2 trans to NA diff,or a t2 driveshaft and rear diff and axles, which i have if you need.

I didn't get the MAF. I thought you could run it on an N/A ecu but you have to have a piggyback to control air/fuel ratios?

Anybody else have any idea?