Ok...I have an interesting little swap done to my civic. I have a 99 Civic Si, with a 94 JapSpec B18C. With this swap of course is an OBD II to OBD I conversion. Well, a couple of things I need to figure out. First off, which would be the better way to do this? Should I make it all OBD II or all OBD I. Both ways will cost a little money, just in two different ways. And another thing, VERY rarely my car throws a check engine light. But tonight it was completely different. Usually I can just cut the car off, wait a second and start the car again and the light is gone and my car is running fine. However, tonight was a different story. I was driving and she started acting all sputtery and acting like she was flooding out. So I stopped at our oh so not wonderful 24 Hour AutoZone to utilize the parking lot lights. Before cutting the car off I fooled around witht eh ECU. I've come to find I have a short somewhere in some of the wires because anytime I have someone sitting in the front seat, the can cut my car off if they move their feet wrong and hit wires. So I checked to see if wires were touching. Nope. Nothing changed when I was fooling with the wires. So I popped the hood and was looking to see if for some reason sensors had come loose. Nope. Nothing. So I decided to cut the car off and see if that would make a difference. Well it did. For a second. And then as was trying to drive home and I was babying her, the CEL cut on, and then would cut off and then cut back on. Not so much in a flashing sense, just in this spuratic way. It has NEVER done anything like this before. If anyone has any suggestions besides a different swap, I'd love to hear them. Thanks.

Christina

 

Since you're running a 99 Civic, you should be running on an OBD2 setup. The 94 JDM B18C requires an OBD1 setup. So what kind of ECU are you running right now? OBD1 right? I would recommend running an all OBD1 setup. It'll be worth it in the long run. It'll also make tuning much easier. For your problem, I am truly stumped. I've never experienced that before. It could be the ECU or the harnesses.

 

I have been leaning more towards full OBD I. However, I've been told that I'm going to have to change my dash wiring harness. How exactly would I do that. I would prefer to run full OBD I, easier tuning and less restrictions. I know finding a GSR wiring harness is my biggest problem on the full OBD I conversion. Is there any other harness that would work? No one I know seems to know too much about this kind of swap. I've been shunned for it, but the challenge is kind of fun. I'm starting to think I got a bad ECU when I bought my swap from OSAKA. I'm not sure. I've been thinking that if I go full OBD I that I will just get rid of my P72 and put in a tuned P28. My plans are to turbo this motor. Light additives. I'm just aiming for 13 second daily driver. Maybe faster later done the road.

Thanks for the help Jay!

 

I'd take a look at the ECU pinout diagram for the critical ECU inputs (ie: crank and cam angle signal wires, VTEC oil pressure check, MAP, etc.) and check those for poor connections. There are three sockets that plug into the ECU...try to eliminate the one(s) that are not problematic first, then start working from wire to wire.

It could something as simple as a poor engine ground as well because those GND points are used by a lot of, if not all, of the sensors (especially the one on the thermostat).

I'd avoid trying to rewire the car to use a two-piece OBD-1 harness. You don't really need to swap the complete harness to convert to OBD-1 anyways. I can think of a thousand better ways to spend my time and money on a weekend.

 

Well, I know that if I run OBDI that I'm going to have to change the engine harness. Right now, I've got OBDII engine harness, distributor, fuel rail, and injectors of course. To convert to OBDI I know I have to change all of that over. However, I've been told that if I put an OBDI engine harness on, the dash harness will have to be changed to. Not sure why. I didn't think that the two harnesses played into each other. If I'm wrong in any of this, please correct me. I know I"m not the most knowledgeable about some things. I know motors, but not to this extent. If there is a better way to do this, please enlighten me. I just don't really want to run OBDII. There are too many restrictions and complications when it comes to tuning and turboing. Thanks!

 

The easiest way to convert to OBD-1 is just to use an OBD-2 to OBD-1 conversion harness. For you, it's probably more specifically OBD-2A to OBD-1 conversion harness.

You don't need to swap the OBD-2 engine/dash harness and associated OBD-2 harness specific distributor, fuel injectors, and alternator for OBD-1 parts. The only difference between OBD-2 and OBD-1 are the connectors for the above components (alternator, distributor, and injectors), the addition of a CKF sensor, and the way the sensors & outputs are pinned into the ECU socket. A conversion harness takes care of repinning the ECU sockets so you can plug in an OBD-1 ECU, and that's all that's really needed to convert the engine so it can use an OBD-1 ECU.

When you go to turbocharge the engine, you'll eventually have to use larger injectors (that are only available in OBD-1 style connectors), so you'll have to solder on a set of OBD-1 injector plugs. You can worry about that later.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">if I put an OBDI engine harness on, the dash harness will have to be changed to. Not sure why.</TD></TR></TABLE>
The '96+ Civic chasis uses a one-piece harness from the engine to the ECU. '94-'01 (OBD-1 and OBD-2A/B) Integra's use a two-piece harness that junctions at the passenger-side shock tower. If you want to use an Integra engine harness, you also have to use the Integra dash harness as well since there's no practical way to separate the Civic harness in half.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IN VTEC &raquo;</TD></TR><TR><TD CLASS="quote">The easiest way to convert to OBD-1 is just to use an OBD-2 to OBD-1 conversion harness. For you, it's probably more specifically OBD-2A to OBD-1 conversion harness.
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I have a jumper harness. However, it seems to be having issues somewhere. Not sure where. Tomorrow (Today) I plan on working on my car in about 12 different ways. One of them is playing with my ECU and jumper harness. Hopefully I can figure out what is going on with my car and fix it. I've heard that wiht the jumper harness I will have problems later when turboing my car. However, no one can ever tell me what problems exactly I'll run into. I've also seen larger injectors for OBDII. If i'm not mistaken, RC makes them. Thank you!

 

I fail to see how a jumper harness would cause any problems unless the harness was faulty to begin with or some Dumas forgets to plug it in.

 

The harness needs to be soldered. Which what I'm about to go do when I finish this post. Hopefully I will have no problems afterwards. It's plugged in. And my civic has never had a problem until the other day. I'm not sure what it is. I unplugged the ECU and checked to see if pins looked burnt or bent, nope. Took the top of it, just to check and see if the inside circuitry was fine and it all looks brand new. So, I don't know what's going on. Hopefully I'll figure it out today.

 

Maybe you could try out someone else's known-good conversion harness, or just buy a new one (since they're not that expensive) if the problem isn't obvious to being with.

I've had a VTEC controller harness snap a wire coming right off the pin once. I never bothered to fix it, but discontinuities can happen like that even tho I never played with/manhandled the harness a lot.

 

I have a 94 stock LS and this exact thing is happening to me. mine's OBD-1