Sup everyone, first off, been searching and reading for several days on this.

Here is my set up that i just picked up and have been working on:

1988 civic sedan dx
B16a swap
pr3 obd0 ecu
currently running NO (ZERO), o2 sensors - don't know why? <--stupid
stock second gen exhaust manifold with single o2 sensor bung that is plugged close

It runs like major fcking ****, huge lumping idle, up and down, up and down, big time.

That's the quick run down, now what I'm trying to figure out is how to make it run properly using two single wire o2 sensors that it was designed for. I bought a cheap 4-2-1 two piece header from ebay with a single o2 bung on the 2-3 bank and plan on getting a second bung welded onto the 1-4 bank. That should work, right? Basically, I want it to run the same as the original stock exhaust manifold without using the stock exhaust manifold.

Here's the header I got:


Every thread I find on this subject never really has any clear answers, some people say wire both o2 sensors together onto one wire, but I am pretty sure that ghetto way won't be ideal. Most people simply say go OBD1 and call it a day, but that takes more money than I want to throw at this thing.

Also, LAST question right now, the harness plugs for both o2 sensors are two different ones, one yellow round type and the other is a green rectangular type, right? Would it be bad if I cut the green rectangular plug off of the harness and changed it to a yellow round kind? I have a few of those kind, but no green plugs.

Here's a picture from hondaswap forum that I got off google to show the plugs I'm talking about:




I am trying to avoid converting to obd1 and just want this thing to run right, not gonna be a race car or anything, just picked it up for a daily classic.

I found this from a while ago and read through it, but didn't really finish the question, so hopefully this might:
https://honda-tech.com/forums/tech-misc-15/crx-b16a-wiring-one-o2-sensor-752990/

 

All you need to do is splice the secondary o2 wire into the primary o2 wire. It's not ghetto at all dude and it works. I ran like that for years before converting to OBD1. Never had a problem or cel. And the plug style I used was C8 pictured above. Welding the 2nd o2 bung in will be fine also. Good luck!

 

Which plugs are you referring to as the "primary" and "secondary"? Is it yellow round plug = primary and green rectangular = secondary? I thought they were both essentially primary sensors since they are both single wire sensors reading different exhaust banks. Not like on obd2 where the primary is at the collector and the secondary is after the cat, right?

I'm sure it would probably run better than it is now by running a single o2 sensor spliced to both connections, but I'd rather it work the way it is supposed to. They are low voltage sensors that could be way off if I don't shield them the right way, right?

 

I have a 90 CRX si with the same jdm b16a swap (obd0). Honestly, I don't have either hooked up, and it didn't make a big difference that I could notice with them installed/uninstalled.

So I bought a dc sport header with only 1 bunghole before the cat, and ran a big wire to it and threw one of the o2 sensors there to clog up the hole. I connected it electrically for the hell of it.

I have no flash codes on the ecu, and the car runs totally normal.

 

This is OBD-0 and NOT OBD-2 so throw that logic out the window...

Yes - the O2 wires need to be shielded as they are logic wires.

You are tryig to thin WAY too into this... If you truly wanted to do it right, you wouldn't have bought a garbage eBay header in the first place.

 

True that the two sensors monitor two different banks because of the manifold/header design.
If your engine is in good condition then there is nothing to worry about when just running one O2 sensor.
I would be a bit concerned if it were a high compression build or an engine that had uneven compression check numbers.

But anyway - the header you show in your pic is funky.
I'm wondering why they didn't weld the bung on the B-pipe.
Right now it's not getting a good reading from the 2-3 bank... it's located to get direct stream of bank 3 and probably little to none of 2.
Compare it to the stock manifold.
I would opt for welding on the second bung for 1-4 on this header.... and maybe even relocate the existing bung onto the B-pipe.

 

i got a d series but essentially the same thing. im running no o2 sensor since... well long story. Anyhew, I dont have any issues with running. also the lopey idle could be caused from your iacv being adjusted improperly.

is your car running really rich or lean?

what do you mean by its running like ****?

 

The sporadic idle is because of the idle control valve or the fast idle thermal valve. one of them is not functioning properly.

 

Haha, thanks for the reminder that its not obd2...not like i forgot...obd0 sucks and this is my first attempt at working with it. I might be over thinking it, but it's better than not thinking and ending up with bullshit problems like a lot of people do.

"Truly wanting to do it right"? I don't mean to downplay anything or make it seem like I'm trying to make this thing something that it is not. All I want to do is not run some crackhead wiring to try to "make it work", ya know? It was made with two o2 sensors, so I'm attempting to run it with two o2 sensors.... Getting that garbage *** header was easier than finding the stock manifold. I've been all over the junkyards around here and thought I'd come across one, but haven't.

 

I thought the same thing about the IACV and was hoping that was the problem. Pulled it off, noticed it was dirty and thought, "Cool, clearly that was the problem" cleaned it up, slapped it on, still the same, hahah.

By running like ****, I mean the idle goes from around say 700 to what sounds like 2000 up and down up and down. Unfortunately, there is no tach on this mean machine, so I can't say for sure, but it is a significant idle range. When I pulled the exhaust manifold off, it looks like it is running pretty rich, same when I look at the plugs.

 

FTFY

 

no where in hasports history has that ever been said

not sure where you got that information

 

check this for your bouncing idle.
http://www.civiclife.net/board/topic...-thermo-valve/

It won't fix your running rich problem... that is going to have to start with you getting a second O2 installed.

 

I don't know where this guy gets his information from, but he's clearly an idiot. He has no clue what he's talking about....pssshhhhh, FIT valve......yeah right, thanks for nothing, bud!
(Shaking my head....that was clearly and obviously the problem....im a dumbass and super big thanks to you 4DREF!)

Took me about 15 minutes to get it off, tighten it up and put it back on, really dumb thing to miss.

Here it is once off:





Here, you can clearly see that the white plastic threaded plug thing had indeed unthreaded itself pretty much completely....


After a bit of messing with it to get it threaded back in:



Then threw it back on, turned it over, completely different car.....hahaha. Big thanks man, i can't believe I missed that. I still have a lot to learn about obd0 cars. I cleaned the IACV and thought it'd be good, but totally forgot these have a FITV.

 

You can get your ecu chipped for less than $50. It's a good alternative to obd1. They can bypass your o2 and make it run like stock or better. If you really want the stock B16 manifold, I have one. PM me.

 

Thanks man, im actually still waiting on my chip and socket to come in, should be here any day now. I didn't have the secondary o2 sensor disabled though because I already have all the sensors and stuff to hook it up and figured it would probably run smoother with both.

Sending you a PM, too

 

i had the same problem. i think i tightened it too much. my car wont idle up at start and on cold days it takes a few tries to start it. i prob need to pull it off again. Glad you got yours fixed