I have a 91 CRX SI with a D16z6. Bought the car a couple weeks ago and there are 4 wires that aren't connected to anything towards the front on the transmission side. I'm wondering if they are the infamous "4 wire o2 sensor" wires or if anyone can tell me what they are used for. As of now, there isn't a o2 sensor on the exhaust manifold. The colors are as follows:

Red/White Stripe
Green/White Stripe
Green/Black Stripe
Yellow(solid)

Sorry in advance for the crappy cell phone picture. I'm trying to get everything buttoned up before the snow flies and any help would be greatly appreciated!

 

They are in the the right area to be for an O2, but honestly they could be for anything.
The only butt connectors on the whole harness -in that area- would be for the reverse switch connection. However is somebody added those afterwards then it could be anything.
Your best bet is to continuity test them at the ECU and see where they are going.

 

green/black and solid yellow most likely go to the back-up light switch on the transmission

red/white and green/white in that area are most likely for the TW sensor on the end of the head

 

i hate figuring out which wires go where! my buddy has the same issue on his hatch, so i'll be watching this thread to see what is the outcome. it my help us out as well......

 

the 2 with the bullet connectors do go to the reverse light switch the other 2 im not too sure of

 

thank you, i do see that there isnt anything connected to that..its on the "top side" of the trany correct? also, I went to the junk yard today, and found that there is a rubber boot over those wires, do i need that boot or will it be ok to just connect them

 

thanks, im def gunna hook that up, this is such a nightmare

 

the red/white and green/white go to the head, its the temp sensor for the ecu, kind of important if you want vtec to work and your car to run right. the two bullet connectors are for the reverse light switch. was the car converted to obd1? looks like you still have the connector to the obd0 one wire o2 sensor

 

thank you!. i pulled back the carpet last night to check out the ecu. to be honest, there isnt a jumper harness. the person before me just plugged the crx wires to the p28! Now im def going to need to get that jumper. the temp sensor is plugged in but it has one wire(black i believe). would that be the o2 sensor just plugged in the wrong spot? im working now, so i cant take pics, will later tonight. im wondering if i should just get a new ex harness and re-do everything

 

there are 2 temp sensors on the end of the head - one has a 2-wire connector with red/white and green/white wires and is the sensor for the ECU - the other is a 1-wire sensor with yellow/green wire and is the temp gauge sending unit

 

which wire would that one be in the picture? except for the 4 bare wires, everything else is plugged in

 

 

OMG I just realized that the o2 sensor plug in that picture you just posted, is plugged in on the head (white plug in my picture) where the(coolant temp) should be. the red/white and green/white wires are the ones that go there correct. Also noticing that you posted a HF harness...is that ok to run on the Z6? bc it seems as if that is definitely what I have. Would just have to run separate lines to the p28 for vtec and 4 wire o2? or do you think its just easier to get a EX harness and redo it all? I really would like this to run well and right now it runs like sh*t. Also have resistor box for the injectors as well. is that not suppossed to be there either? Thank you guys very much for the information. I have been around Hondas for awhile, but none of them had a swap, let alone something that has bare wires floating all over the place.

 

my set up on both my cars (88 std hatch with an si body harness, 90 lx with ex sedan harness) i de loomed my engine harness, removed the o2 sensor wire, de pinned the obd0 dizzy plugs at the fire wall harness, and replaced the wiring and plugs with the obd1 dizzy plugs from an obd1 engine harness.

for my vtec plugs, electronic vss, and 4 wire o2, i made a seperate harness with it's own plug that i loomed into the factory harness for cleanlyness, but my jumper harness has all the provisions for everything but the vss signal wire (i'm running a gsr cluster in my hatch, the vss part does not apply to you if you still have a cable driven cluster).

i'd immagine it runs like ****, the computer probably thinks the car is max cold (like -30 degrees?) and can't tell how to mix the fuel mixture since you're missing an o2. is the car even running obd1?

 

to be honest, im not 100% sure if its running obd1 or not i thought it was. from the pictures above posted of the HF harness, I would suspect not. It does have a chipped p28 ecu and from what i can tell, there isn't a conversion harness. I bought the car from a guy who bought the car swapped and not running, he wired it (some spot with wire nuts, which im going to de-loom and fix) and got the car to run. thats why im not sure if he just plugged the HF engine harness to the SI body harness then plugged the SI into the p28. the MAP and TPS sensors were moved to the correct locations on the IM, the injector wires are all electrical taped with the resister box still there. im about to just take off the whole engine harness, get one from a EX which I have found at the junkyard, plug that all in...get the jumper conversion harness from Rywire and pray to god that works.

or do i keep the HF harness, get the loose wires connected properly, Rywire jumper harness and then run a separate harness with the vtec and o2 to the jumper?

just checked the dizzy, and injectors, obd1..check

 

this is what im dealing with at the ECU

there is also a flat plug that isnt connected to anything, i checked rywire's pictures, they have the same one attached to their harnesses, could be used for the o2 and vtec...im starting to think that from this picture because i have 3 connectors from the ecu, 3 connecters coming from that electrical taped mess of a harness and the spare flat plug, that i have a obd1 to obd1 conversion harness...any thoughts