swap questions
 

I am swapping a de out of a s14 into a 89 hatchback...

Is it extremely hard to splice the harness?
Or would I be much better to just use a 91-94 harness and make the swap a lot simpler?

Also which ecu should I use? the s14 or a 91-94 ecu?

Re: swap questions
 

The only difference between the s13 and the s14 KA's is the OBD technology. If you chose to use the 91-94 ecu you need to use the 91-94 TB it uses a different TPS, also since you already have the existing PAIR valve you are good to go, it was switched to a temp atmospheric sensor in 95-98 and you also change out to one o2 sensor instead of 2 o2 sensors found before and after the CAT on the 95-98 OBD2.
Splicing is a biotch and takes maddd hours I would just pick up the 91-94 wiring harness as well and you are good to go.