So i just bought an 89 crx si shell with no engine, engine harness or ecu.
I just bought an obd2 d15b motor and cable tranny off my buddy and i need to know do i have to get the engine harness that originally came with my crx or do i have to find the engine harness for the d15b? i've been told the d15b originally came out of a 96 civic coupe and i have no idea which engine harness i'm supposed to get, i've heard a few different things. The engine and tranny came with a P2P ecu, is this correct?

 

You need to get the harness that matches your car. And it will be best if you convert to obd1 if it's a d15b vtec motor, if it's not a vtec motor then u have the option of going obd1 or staying obd0.

If you need a new engine harness I can build you a brand new stock replacement or ovd1 converted harness. Pm me

 

It's a d15b vtec and its obd2, i can still convert it to obd1 even though the engine and ecu are obd2? and rywire makes an obd0>obd2 jumper harness for the ecu, a harness for the obd2 dizzy and for the alternator. Am i gonna need all that?

 

i would save yourself the trouble and just convert to obd1. if im right rywire only sells an ecu jumper harness. which would mean that you will still need your stock engine harness for the jumper to function. so i would personally just go with obd1. get yourself a p28 and then you can use an obd1 or obd2 distributor that matches the motor.

 

Whats the easiest way to convert to obd1? any diagrams or anything you can refer me to?
I'm young and new at all this **** so i gotta learn somehow!

 

find the shop manual, i believe hondahookups dot com has them? all the way at the end of the manual there will be diagrams. i will warn you, if your not familiar with wiring schematics it will be very overwhelming at first. once you get the hang of reading them it because like second nature. from there you can make your own harness. or you can purchase a harness from the junkyard, ebay, the marketplace or

myself and Clipsed build them.

 

So let me get this right, i convert my car to obd1 and then buy the adapters for obd2?

 

no. convert to obd1. and thats it.

im assuming you have the stock intake manifold for that motor. use the same injectors that are on the manifold. use any obd0 or obd1 alternator (they are pretty much the same). and get the distributor that matches the motor (doesnt matter if its obd2 you can use that with an obd1 ecu). and then just get a p28 obd1 ecu. then you just need a 4 wire o2 sensor and your set to go. no need to convert anything to obd2 (just your injectors if thats what came with you manifold).

 

Ok I think I know what he is trying to ask. Basically he is confused with what you are saying. The car started off being OBD0. He has a OBD2 motor. Get a P28 ECU. Get a jumper harness that goes from OBD0 to OBD1. Then with you running an OBD2 motor you need a dizzy jumper from OBD2 to OBD1 and swap to an OBD1 dizzy. Im pretty sure thats right but if anyone disagrees please feel free and school me. Thats basicly what I had to do but I went from OBD0 to OBD1 so the OBD2 motor is uncharted water for me. Hope this helps.

 

Would i not have to get a distributor jumper from obd0 to obd1 since my car is obd0? not obd2 to obd1?

 

You guys are confusing him.
OBD = on board diagnostics
obd0 = 88-91
obd1 = 92-95 or so
obd2 = 96+ I believe, something like that.
as newer cars are introduced, more OBD is introduced to diagnose engine problems, and keep stuff running smoothly.
For tuning, you want OBD1 ideally.

So, your new motor needs to be 'converted' to obd1.
replace the obd2 distributor with an obd1 distributor (there was something online about just re-wiring it, which works perfectly fine)

you NEED a CRX Si harness, not sure if there is a difference between 88-89 and 90-91 harnesses. It is too much work to mod the harness from your new motor...

Once you get the CRX Si harness, install it on the OBD2 motor (not all the plugs will line up)

so now, you just need to figure out what sensor connects to which plug...

ECU wiring: get an OBD0-OBD1 jumper harness. Zerg industries makes a decent harness for cheap.

the jumper harness comes with a sub harness which wires up everything else. the instructions that come with it are very helpful. wires for the o2 sensor, vtec...

as far as the alternator goes, they are basically the same as "crx si-r" said.
if you get an obd0 alternator, it should be just plug and play... not sure if the belts are different, don't think they are.

for injectors, if you use obd2 sensors I think you just delete the resistor box and solder all the wires together. you can use obd0 injectors with a resistor box. a resistor box is useful if you plan on boosting.

questions?

 

obd2 honda engines are 96+. i have a d15b in my hatch and its obd1 not obd2. is this not the jdm vtec engine?

 

Read through all the posts and agree with Canadian_EF - it's confusing!
... and to make it even more confusing there is no such thing as OBD0!
OBD is an industry standard and the first release of the standard was version 1.... hense OBD1.
Everything before that was before OBD even existed. Proper terminology is 'pre-OBD'... but we just call is OBD0 for unknown reasons... clearly there is no such thing as version 0 for anything much less OBD 0.

Canadian_EF got it spot on.
All sensors and such on the OBD2 motor work with an OBD1 ECU - this is the best way to go about this swap.
You will need to convert your OBD0 engine harness (your stock engine harness) to plug into the OBD2 sensors. This may require extending some wires (the coolant temp switch for sure), and changing plugs to match the OBD2 style plug (distributor and alternator)
If you choose to use the newer OBD2 injectors then you will have to delete the resistor box as stated before. Additionally you will find that the injector clips won't go right on. You can swap out the injector clips for the OBD2 style, but as I remember the OBD0 clips will work just fine with minor mods.
You will also convert your under-dash harness (jumper harness) to plug into an OBD1 ECU.

The last remaining trick is to get the OBD2 distributor wired up properly to your OBD0 harness so it plays nice with your OBD1 ECU.
The sensors in the OBD2 distributor are completely compatible with the OBD1 ECU so save some monet and don't bother getting an OBD1 distributor.

 

Canadian EF - Thank you very much i finally understood that!
Thanks to everyone else too you're all a great help.
Now the real question, does anyone know where i can get a crx si engine harness in Toronto, Ontario, Canada? or am i going to have to grab one online at some point?

 

I wish I could remember the name of the site, but, there is a junkyard part warehouse search thing. Your best bet is to look up a junkyard or autowrecker in your area and go pull one off. It's pretty easy, just need a few wrenches and a screwdriver or 2. Never know what parts you might see...

 

I can build you one already converted to obd2 injector plugs, resistor box deleted, fan switch converted to obd1/2 style, distributor wiring pre made to plug n play and 4 wire o2 sensor pre wired. All you would need is the ecu jumper, which I can build as well. Pm me if interested.