ok...

im gettin my 1991 Civic DX hatch in a few weeks now, and was gonna purchase a built ZC from the person but hes decided he wanted more money ($1400) so ive decided to go with a different motor...

either a D15B/Y8 and turbo later or a B16 all depending on how much i can get a motorset for...HMotorsonline sells the d15b with everything i need for right around $800-900 and the B16 fir around 1500...

im gonna end up doing the swap on my own im sure and have been reading and searching and when i think i got it, i get something confused and search and read some more...

ive never done a motor swap on a honda and im a LITTLE confused on the whole obd0-1 and wire harness stuff.


im sure either way im gonna need to do the OBD1 conversion to run any motor i get, and i know that VTEC wiring is something different altogether.

if im swapping a d15/b16 into the civic, and throwing out the old harness and motor, why cant i just install the motor and the appropriate wire harness?

ive been searching for anything i can find as far a how to and have found some things, but im just getting confused.

why do i need to convert my DX wire harness to OBD1 if im just gonna use the one that comes with my motor? from what i understand, the chassis harness and engine harness are 2 different things entirely, so why would i need to convert...wouldnt i just need like to splice 1 or 2 plugs so that i can mate the new motors harness?

or what majority of what harness is staying? am i adding a few/changing a few plugs on the new motor harness or am i modifying the entire harness from the old motor to work with the new?

i think i have the whole VTEC thing down, 4 wires seems simple enough..

my main thing is i dont really want to pay hundreds of dollars in jumpers and sub harnesses...i enjoy this sorta thing(i have fun messing with electronics) and im confident given proper instruction or base to start off i can do it..

if someone can help me solve some confusion that would be great, thanks for your time guys

 

im kinda in the same boat as you but what i have come up with i could be very wrong but you need to go from a obd1 ecu to a jumper harness to your existing obd0 harness to your motors obd0 harness to ajumper harness connecting to your obd1 dizzy..im doing a b18a1 swap and i picked up an si harness that was obd0 with the multi point injector part and purchased the obd1 conversion harness for the ecu and dizzy for like one sixty five please correct me if im wrong someone cause im steppin out on a limb to try an help

 

You need to convert the DX harness because a MPFI engine harness will not plug into your DX underdash harness, the underdash plugs to the MPFI engine harness are completely different. You don't HAVE to convert to obd1 but it will make your life alot easier especially if you are going to be running a d15b or a b16 (unless you can get your hands on a pr3/pw0 then it's easy)

To convert the DX over to MPFI you simply just need to run 4-6 wires into the engine bay. That seems like ALOT less work than cutting plugs and splicing.

You are modifying the current harness to accept the new motor.

Here are the writeups that people have done the obd0 to obd1 conversion harnesses themselves.
https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/d-i-y-faq-obd-0-obd-1-pinouts-conversion-help-1319235/ (ECU conversion)
https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/obd0-obd1-distributor-wiring-1349052/ (Dizzy conversion Post #7)