I am in the beginning stages of piecing together everything I need to swap in a JDM OBD1 B18c into my 93' Civic CX. As I have discovered, there are many wiring routes to go. I would like to utilize the P72 ecu that comes with the swap. What will be the simplest option for me to correctly wire up this beast, knowing that the RHD jdm harness will be useless in my USDM car. I was on ebay and found a used USDM OBD1 integra gsr wiring harness. Do any of you know if this will work on my JDM b18c? Any input is appreciated!

 

Why do you think the JDM ecu will be useless? I think you're confusing it with the RHD wiring harness on the B18C. The shock tower and battery connectors on the JDM wiring harness are reversed. You can either use your Civic's wiring harness and probably have to lengthen a few wires or get a USDM OBD1 B18C1 wiring harness. You'll also have to wire in VTEC, knock sensor, and butterflies.

edit: Sorry, I just read your post again and it looks like you knew this already. Yeah, getting another wiring harness is the easiest route (that's what I did). You can just unhook each connection on the old one while hooking up the new one. That way, you won't have any problems with where each plug goes. I still haven't gotten the butterflies to work yet (lazy), and I've read that some OBD1 B18C's need a ground for the butterflies, while others need a 12V signal or something like that.

http://www.hondaswap.com/forums/inde...howtopic=41608 This is pretty helpful as well, although I found that not all of the information applied for me.

 

thanks for the help!

 

No problem. Make sure you do all the maintenance/tune up things you can while the engine is out of the car.

Timing belt
Water pump
Clutch/flywheel
PCV valve
Sparkplugs/wires
Distributor cap/rotor

I wouldn't say that any of these are absolutely necessary, but some of them are much easier to do while the engine is out..especially the first few. You can also never be too sure about a used engine that's been sitting for 5-10 years.

Search the archives and you'll find everything you need to get these things, as well as the swap, done.

 

One final thing...what catylitic converter-cat back exhaust combo would you recomment? I want a high flowing exhaust out of the box with no welding required. Should I just buy a catback manufactured for a 92-95 hatch with the standard d-series?

 

My cat didn't bolt right up to the JDM B18C header (I think it's a 2.5" collector on the JDM header), so I had to take it to a muffler shop.

While they were trying to make something so it would bolt up, my stock exhaust fell apart. I told them to do a custom mandrel bent 2.25" exhaust instead, but they had to rush the job because they were closing.

It was a bit loud for my tastes, but I had planned on getting that done in the first place. Anyway, six months later, it rusted through and broke right after the cat.

Since they rushed, it was all one piece from after the cat, including the muffler. Nothing could be salvaged from it since they just cut and welded everything together, and I had to basically get another exhaust. I went back to stock because the place was gay, but honestly, I prefer the sleeper look and quieter sound over the few horsepower gain.

So basically what I'm saying is you should get whatever cat-back you like that is made for your car. You'll probably have to get a shop to make the cat and header mate though; this should be less than $100.

By the way, make sure you know how the mounts and brackets will go in when you drop the engine in...especially the rear bracket. I forgot to put that in when I dropped the engine, and it was a bitch to get it in right afterwards. You've probably heard that it's easier to put it in from underneath the car...I didn't do that, but I can see why it would be eaiser.

Damn, that was a lot longer than I intended.

 

I would like to disagree with thist approach. As they are both obd1, your stock harness will work and all the plugs are the same. If you have an si (already vtec), then every wire should already be present. All you will need to do is lengthen the wires. You can solder or be cheap and use nuts. Either way, all plugs should line right up. That's the point of having a wiring standard to begin with. This will trim MANY hours off your time, as replacing a harness is the worst excercise (imho) anyone can go through.

 

He would have to replace the JDM harness with his stock harness or a USDM B18C1 harness, so the amount of work is about the same. With the stock harness, I've heard people say that some of the wires have to be lengthened. An OBD1 B18C1 harness won't require any lengthening, but will cost a little more since he has to buy it.

If you go back and read the posts, you will see that I already stated this, and he has a CX, so VTEC needs to be wired.

 

CX. Foo.

Well, another approach would be to leave the stock harness in place and do the wire lengthen, plus drop the vtec wires in place - add to the harness. There are easy obd1 subharnesses available like this one: http://www.boomslang.us/extension.htm

Then, you can get an extension on ebay and wire into the extension harness. Personally, I hate removing wiring harnesses. On my 91 integra, removing the harness was a complete nightmare.

Incidentally.. is the cx multi-point or anything nuts like that? ie. does it have 4 injectors? If not, maybe the full gsr harness isn't such a bad idea. But, of course.. if that's the route.. hope you have your helm manuals for wiring diagrams.

 

When you say stock harness, do you mean the one in his CX or the one on the engine? He has a JDM engine, which means the connectors to the shock towers are reversed, and lengthening won't really work unless if each side is cross across the whole engine bay. He has to swap out the harness no matter what, and using an OBD1 B18C1 harness will require a little bit less work (at a little more cost though).

It's really not that difficult when the engine is out of the car. Go one plug at a time, and there's almost no way to get it wrong. There might be a plug or two that don't get connected.