OK, I have tried searches and chased down different links but am getting more confused.

Are there differences in the Si/EX engine wiring harnesses in the years 1988 through 1991, and are they diff. substantially (and if so, how?) from 1986/7 Si engine harnesses.

 

no diference between the 88-91, but my guess is a substantial difference from 84-87 since the engine itself is completely different.

 

i have heard the 88, 89 and 90-91 CIVIC harnesses are all different. i do not know this for a fact though. try IMing superhatch as he has some experience with harnesses.

 

as far as i know the following harness are all different

88 HF
88 STD
88 civic sedan/hatch DX/LX
88 crx dx
88 crx si

89 HF
89 STD
89 civic sedan/hatch DX/LX
89 crx dx
89 crx si
89 civic si

90-91 HF
90-91 STD
90-91 civic sedan/hatch DX/LX
90-91 crx si
90-91 civic si
90-91 civic EX

from my experience they are pinned differently to the engine harness connector(not at the ecu)

this list is part first hand knowledge and part guesstimating

 

so maybe 90-91 could be lumped together (EX and Si both)...still the pinouts are diff. btwn individual years of Si?

the hasport swap article in nov. of 2001 said if i remember in putting b16 into 86 crx si that only the 4 wires assoc. with vtec had to be changed, and elsewhere that 88-91 si wiring harness could be used....i don't know about the integra 90-91 obd0 engine wiring harness

so i am still a little puzzled, but guess that in the best of all worlds that what i need is a 91 si harness - crap, i just need something that works....