98 Spyder GS (4g64) Rear o2 sensor wire location

[Hortanica]

Ok, so here's my 2nd, potentially stupid quesiton.

i can not find the rear o2 sensor plug in the car at all.... Ive searched the forums, looked in the manuals, and havent found anything . there is no wire in the normal location (under the driver seat by center console), and instead of the wires is a sealed rubber plug... I have also completely removed the driver seat and carpet and there were no plugs/wires under there.

I had a buddy remove the exhaust, and i didnt look to see where the rear o2 fed itself into the car since...i thought it would be the same as the other 2 gsx's ive used as donor cars. Well, when i just went to plug it in/wire in a simulator i cant find it . Its not under the seat as there is a plug sealing the hole that the gsx's used to feed the wires into the car with. ive looked all under the carpet but have no idea where it is. any help would be greatly appreciated...

also, i just traced back the wires off my 96 gsx to behind the radio and plugged into, what looks like a relay...
when i look behind the radio of the 98 spyder there is no relay for the o2 there, only the one for the security alarm (i think thats what it is for)

any suggestions/help?

 

[GIRman67]

seeing as there is a plug under your seat instead of a hole and no signs of cables or plugs I would venture to guess that this car didn't have a connector when you bought it the previous owner may have an eprommed ECU that has erased that check and removed the cables just a suggestion

 

[Hortanica]

Thats kind of what i had thought, but it just seems weird that he would completely delete it...plus the guy i bought it from didnt do anything with the car except ebay halo lights, led washer fluid squirters, and sweet stickers all over the car .

oh well, the evo ecu is (sort of) in im having a couple of problems with that, but im gonna make a new topic to discuss that one.

 

[Hortanica]

I just want to update this, but i, randomly looked at the head/intake manifold today and noticed a couple ports on it that weren't on the 4g63t head/manifold.

The one im assuming was for the EGR, but the other was the same 4pin square connector that the front o2 uses, and it had a pigtail off of it that would have ran down the back of the engine, and im assuming plugged into the rear o2. the only weird thing is the plug on the pigtail was also the same 4 pin that the front o2 uses. so tomorrow im going to look at the harness at the ECU and see if the colors match up for the rear o2.

 

[Hortanica]

I know this has been a while but i figured id update anyways.

On the 4g64 Harness, the o2 sensor is ran different than the turbo. it goes ECU>connector 1>pigtail>o2 sensor pigtail.

ECU is self explanatory
Connector 1: Its on the same section as the injectors/cas/tps/egr/mdp plugs. its the same 4 pin square type as the front o2 sensor, and has the same black white red and yellow wires. (white being the signal)
Pigtail: After looking at the 4g64 head, the o2 sensor had a pigtail setup that ran from right next to the egr to the bottom of the block and attached there.
O2 sensor: from what i can assume, its the same o2 as the front..its the same 4 pin square connector, not the one from the 4g63t gst/gsx cars..

i have no idea if i just have a weird car or if this is just normal..but the reason i know that info is true, is because i am now logging my innovate lc1 wideband through the white wire on the connector by the injectors by splicing the white wire with the brown on the lc1....