Hi, I have been doing a project car on my spare time and I have started putting the new engine in. I bought a 91 talon tsi (FWD) 2.0T and decided to put a 4g63T in it. I have hooked up all of the turbo lines so far, and I was wondering if I should use the new/old wiring harness or the new/old cpu? If anyone could help let me know. Thanks.

 

You should use the turbo motor's harness and ECU. If you think about it, the old ECU doesn't have the timing or fuel maps that the turbo ECU has (or vice versa) and if you used the non turbo ECU on a turbo motor, you may ruin a perfectly good swap. The harness you'll need just for sensors on the turbo motor that the n/a motor doesn't have.