I have had a difficult trouble finding info on this obd2b to obd2a swap. I have a 00' civic ex automatic. I have swapped a 98' d16y8 long block into it. I used 00' harness and distributor. Everything thing seemed to connect fine, no extra harnesses, and all ground are tight. It runs with 00' ecu in car but idle surges as though iacv is bad (sets po505). removed 98 t/b and swapped 00' t/b with no change. also tried swapping 98 ecu into 00' and vehicle would not start. do i need to use obd2a harness on engine? or jumper obd2b harness to obd2a and use 98 ecm? any info would help. I'm at a loss.

 

you need a 96-98 d16y8 harness and ecu

 

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/2000-civic-ex-d16y8-into-1998-civic-ex-3026213/

You will need to do the opposite... use everything off the 00 y8 onto the 98 and you'll be good. Use the 00 harness, distributor, ecu, intake manifold, etc... the head is even the same so you won't need to switch those.

Make sure you use the im from the 00 because 99-00 has air injection and 96-98 does not.

 

i tried using the 00' intake manifold and it created a giant vacuum leak. you could spray the top of the intake where the mating surface with head was, and it would change idle/stumble. also appears the ecm harness connectors are same but older ecm is longer. could it be a 98.5' ecm. ive heard there is a vin split between august and september.