i have a 96 z28 it has four o2 sensors. three are plugged but the one furthest away near the transmission is plugged into a little wired box about one inch long and half an inch wide does anyone know what that is?

 

Sounds like an o2 simulator. If so, it basically send signals to the PCM simulating a working o2 sensor and a proper functioning catalytic converter. People use them to remove the cats or install an ORY without throwing codes.

http://www.ws6project.com/user_stor/...simulators.jpg

 

so when you use it you only need one. see the person who own before gutted the driver side cat and welded some crap exhaust on it but im putting head gaskets in it right now and throwing some headers on it. i will be running straight headers until i can afford to put exhuast on it will i have any trouble. Sorry i dont know what ORY is.

 

ORY = off-road y-pipe. A y-pipe with no cats.

If he only gutted one cat, he's a moron. Chances are one became clogged and instead of replacing it, he just gutted it. That would explain why there is only one O2 simulator. When you delete the cats, you need one simulator for each sensor.

 

You will go deaf with open headers. I did it for two days before my exhaust was done and only drove the car once. It will idle amazing, with a badass bass note, but give it any gas and its "front row at Nascar" loud. Way worst then I expected, and noticably louder the a cutout after an ORY.

Not to mention needing a tune and the chance of cool air hitting the o2s making it run like ****.

The sims are only for post-cat o2s, you need the front ones.

 

im broke right now and have been walking for a couple of months. i came a long the z28 for cheap now i know why it was but since i have already invested some time i cant turn back i have a friend trying to hook me up on the stock heads and im saving money on the gasket set but after the struggle with the stock exhaust that crap is not going back on. The stock exhuast was a pain in the neck to get out i finally just pulled the heads all the way out and said it is not going back in. i also found out that the person who own it some how broke the ac/heater core so thats coming out to i want to find a way to keep the heat im not worried about the ac cuase he rip all that crap anyways. I got a mess on my hands all im doing is going back to stock execpt for headers.

 

Yes, now is the best time to do your headers.
Well you can drive it with open headers no problem, just don't use any o2 sensors until you get the y-pipe on or if you can connect 18" extensions on the end of the headers. Like said above, fresh air hitting the o2's will make it run like crap.
Also don't expect to be able to go anywhere far without drawing A LOT of attention to yourself. It will be deafening and a cop will pull you over in a heart beat.