OBDII engine harness second O2 sensor adapting

[Honda4VW]

An EX in a 96+ civic has the o2 sensor in the dash harness. This harness does connect to the ecu with a single plug, which connects the o2 sensor among other things

[Cheetah]

so now I am concerned. As you may have heard I have the 98 dx and I am swapping in a '00 ex engine in my car. I have the engine, tranny, ecu, and engine wiring harness, and aftermarket headers ready to go in. So, how am I going plug in my second (after the cat) o2 sensor? :(

problems, problems. And I thought this swap would be easy. Thanks for help!

[Honda4VW]

Yeah I thought it would be really easy too, but thorough research has led me to finding that the dash harness is needed to do the swap and give the car a factory look. If you are using the Y8 harness, you either must adapt the harness to include the second O2 sensor, or replace your under dash harness. As you may or may not have noticed, there is a rubber seal right about your catalytic converter that houses the connection for the second O2 sensor. This is where the interior harness connects up with. This dash harness is a very expensive item, but im letting it go for pretty cheap.

[Cheetah]

So how would I adapt my current set-up to agree with the second o2?
Reason I ask is I already have ALOT running off my current one like alarm and several accessories, and indiglos.

Is installation of the new one hard?

[Honda4VW]

Its a lot of work to put in a dash harness. Its not too hard to adapt your current setup though... just need to know the pinouts

[Cheetah]

dude I have no idea. I'm guessing pin outs is the diagram showing what each of the points go to on the back of the ecu?

[Honda4VW]

pinouts are the actual pins coming out of the ecu. Check out the following:
http://www.hondaswap.com/swap/viewer.php?id=58

This explains it a little better, plus gives the descriptions of the pinouts, which will help you with what you need.[/url]

[Anonymous]

dont wanna tackle the harness? get an o2 simulator!

[Honda4VW]

The problem is a putting a vtec engine wiring harness in a non-vtec model car leaves you with no plug for the second o2 sensor. Even with a simulator, you still have to find and pin the harness to connect it.

[Jaker]

It would be immensly easier, and much less time consumming to use an engine harness from a 96-98 Civic. You could just use your current harness, and add the wires for the Vtec, and make an extension to the 2nd O2 sensor wiring to reach the Vtec OEM location. Or you could get a 96-98 EX/Si engine harness and swap it onto your 00 engine.

The under dash harness is not garanteed to work. It is possible that Honda could have made changes to the under dash setup as well, and the 00 under dash wiring won't match up.

[Cheetah]

well, problem is I just bought a 2000 ex manual engine wiring harness. So, I think what I'm going to have to do is extend the wires from my second o2 sensor and somehow find the connector that plugs into the ecu and soder? the wires.

Or, what happens if you just dont use the second sensor? Does it affect performance? Bad situation.

[Jaker]

Return it. Sell it. You will not get the 00 engine harness to work with the 96-98 chassis harness. There are several differences. Too many. Trust me. This stuff is my business. This stuff is my life.

Buy a 96-98 engine harness. Period. Or mod your existing 96-98 CX/DX harness.

[sohctrance]

I had this same problem swapping a 98ex engine into a 96 dx. I wound up going another route and spent a lot of money doing it. I went with a 95 ecu and using a obdII to obdI conversion harness to eliminate the need for the 2nd o2 sensor. I picked up a little extra power with a different chip, but not enough for the cost of the ecu and harness. I wish I had found a chassis harness and went that way b/c the ecu was $150 and the harness was $125.
Just my $.02 worth.

[Cheetah]

Crap!!

I dont know if I can just use a 96-98 ex harness BECAUSE the engine is a 00 and arent there differences in those 2? Remember, OBD2a and OBD2b,

grrrrr

[Honda4VW]

I believe you can use a 96-98 harness on an OBDII engine, and vice versa. Just have to have the corresponding ECU to the harness

[Cheetah]

Ok dokey.

I hate to throw a monkey wrench in this....but I have a idea....

What if I buy a OBD2 > OBD1 conversion harness because I HAVE HEARD it gives better performance....and just uses ONE o2 sensor?

And nobody ever told me, what happens if the second o2 us not hooked up?

[Ek9]

if your second o2 isnt hooked up you will have check engine light.. :(
get obd1 conversion harness :D

[Cheetah]

IF I do use the conversion to OBD1.. how does that give me better performance that I've heard of?

What about emissions testing? I think they are going to stop doing it around here anyway but just in case.

And do I need anything special for the conversion other than the harness adapter and a very good primary o2 sensor? Also that begs the question what o2 sensor? for a 95ex or a 00ex?

[sohctrance]

You do need the obdII to obdI harness, the plugs won't even fit otherwise. If you are to go this route I suggest the p28 ecu. I will give you contact info on for the guy I bought my ecu and harness from, he was very helpful (fhperez@hotmail.com). Before I swaped ecu's etc. I had all kinds of CEL's and problems. I haven't had a CEL since. Hope this helps.

[Cheetah]

crap

Wanna know why that sucks? I just bought a 00 ex engine wiring harness and ecu for $200. Guess I would need to sell now huh?

so you are saying I need a 92-95ex engine wiring harness and its p28 ecu?
Wait a minute...then why do they even make OBD2>OBD1 conversion harnesses for? I'm confused. ha, all this for a o2 sensor!

and if I do do this, is the skunk2 chip worth it?

[robtec]

buy the conversion kit and forget about the o2 sensor. all you need is a p28 and the conv. kit

or buy a race cat,it comes with a opening for the second o2 .my brother is using this setup in his 2000 gsr and it perfoms better.

i also hear something about a device that plugs betwen the o2 sensor and the ecu. it tell the ecu that your o2 sensor is working fine,so you can eliminate the sensor or eliminate the cat and the check engine lite does not light up

[Ek9]

find a conversion harness (obd2a-obd1) online somewere u mite need to jump some of the wires on the harness after that because of the iac

[i-all-ways-win]

Well they’re a down side on using the p28 ecu. Here in California when you smog your car they put it on a dyno and they plug a cable in to the computer of your car. The smog machine is reading all the codes of error and sensors. So it will work for now but you still need to figure out the second o2 sensor.