AlwaysCode390

Hey Guys, I am throwing a passenger side FRONT code and drivers side REAR code. When I went to my local chevy dealer for genuine delco replacement o2 sensors the guy asked if I needed the ones on the manifold or before the cats ( I didnt know what to tell him ). Well I am guessing the FRONT is on the mani, and the REAR is before the cats? Are there 3 or 4 sensors? I know the 96 had DOUBLE cats, but now I am running edelbrock shorties , y pipe with ONE cat ( so where is my other sensor for the other stock cat that is gone?! ). Obviously the exhaust was on it when I bought it or I would know a little more about it. I have also heard small things about simulators, where do I get them and how much are they? Also how do they work....do I have ONE real o2 and then put simulators on all the other holes? THANKS---

Z28SORR

On dual CAT cars 96 & 97's there are 4 O2's. One on each side (on the manifold) before each CAT and one on each exhaust pipe after each CAT.
The forward two O2's are needed for the PCM to control the mixture. The aft two O2's just tell the PCM if the CAT is functioning and can be programmed out or replaced with sims.
As your car has been modded it may have sims. or they may have been programmed out and the wires taped up. Or it may have three O2's.
Just going to have to look.

AlwaysCode390

Or it may be throwing codes because the last guy to have it was a douche and didnt do ANYTHING right when modding this car.....lol, hahaha. Oh well, thanks bro, atleast I know WHERE to look now....shouldnt be too hard to fix up, THANKS---