So a while back I bought a 1997 Camaro RS with the 3.8 V6 as a project car for my nephew who just turned 16.

The car is a little rough around the edges but it's got a solid body and good paint.

Anyway, the exhaust is missing from the Cat collector back. I bought a set of headers with the collector to the Cat. The Manifolds and Y pipe have O2 sensors, but my question is should there be an O2 sensor downstream of the Cat?

I've got one in each manifold and one in the y pipe just before the catalytic converter, and looking under the car I only see connectors for three O2 sensors, should this car have four?

 

no there should be one on each side and one after the cat.

 

That's odd because the y pipe I took off and the y pipe that came with the headers both have a bung for the O2 just before the Cat.

So you are sure it should be downstream, just after the Cat?

Is that what the PCM expects?

 

I would have bet money there was 4. I did not have time to find a diagram. If you look at the pics in my 1996 thread you can see bung holes in each of the OBX headers and one right before the CAT. I assume there has to be one after the CAT because that is needed to know if the CAT is working. The whole reason for the down stream O2's exists. Seems like every thread I found on the subjects says there are only 3 then many turn into an argument with guys saying there are 4. I know 3 was the norm back in the day on a single CAT exhaust. But Late model cars all have one on each side of the CAT and one in every manifold.

EDIT: It was bugging me too much. Rock Auto lists O2s that fit manifolds LH & RH. Pre and post CAT. So Rock says 4. One of the listing mentioned Auto or Manual. I wonder if that is it? Mine was a manual. I also found on set of 3 O2 list as a kit for the 3800 but it said except Canadian built?? I though all 4th gens where Canadian built. Seems like GM manual will be the only answer.

When I think about it, having bank 2 2nd sensors in a manual makes a little sense. When down shifting they may be trying to control backfires or "burbaling" more then not having it.

 

sorry not completely sure on the 97 v6, there should be sensors before and after the cat to make sure the cat is working. being you can only find 3 wires I would think the third one would be after cat.

 

Heated Oxygen Sensor Bank #1, Sensor 1 (V8 VIN P) Mounted in left Exhaust Manifold
Heated Oxygen Sensor Bank #1, Sensor 2 (V6 VIN K) At front of Catalytic Converter
Heated Oxygen Sensor Bank #1, Sensor 2 (V8 VIN P) At left Catalytic Converter
Heated Oxygen Sensor Bank #1, Sensor 3 (V6 VIN K) At rear of Catalytic Converter
Heated Oxygen Sensor Bank #2, Sensor 1 (V6 VIN K) Mounted in Right Exhaust Manifold
Heated Oxygen Sensor Bank #2, Sensor 1 (V8 VIN P) Mounted in right Exhaust Manifold
Heated Oxygen Sensor Bank #2, Sensor 2 (V8 VIN P) At right Catalytic Converter
Heated Oxygen Sensor Bank 1, Sensor 1 (V6 VIN K) Mounted in left Exhaust Manifold
Heated Oxygen Sensor Bank 1, Sensor 1 (V8 VIN P) At left Exhaust Manifold
Heated Oxygen Sensor Bank 1, Sensor 2 (V6 VIN K) Mounted just forward of Catalytic Converter
Heated Oxygen Sensor Bank 1, Sensor 2 (V8 VIN P) At left Catalytic Converter
Heated Oxygen Sensor Bank 1, Sensor 3 (V6 VIN K) Mounted just to rear of Catalytic Converter
Heated Oxygen Sensor Bank 2, Sensor 1 (V6 VIN K) Mounted in right Exhaust Manifold
Heated Oxygen Sensor Bank 2, Sensor 1 (V8 VIN P) At right Exhaust Manifold
Heated Oxygen Sensor Bank 2, Sensor 2 (V8 VIN P) At right Catalytic Converter

 

Thanks Craby, so there should be 4 sensors. The PDF shows where the O2 Harness breaks out of the transmission harness. You may be able to see that or at least feel for the break outs from under the car.

Heated Oxygen Sensor Bank 1, Sensor 1 (V6 VIN K) Mounted in left Exhaust Manifold
Heated Oxygen Sensor Bank 2, Sensor 1 (V6 VIN K) Mounted in right Exhaust Manifold
Heated Oxygen Sensor Bank 1, Sensor 2 (V6 VIN K) At front of Catalytic Converter
Heated Oxygen Sensor Bank 1, Sensor 3 (V6 VIN K) Mounted just to rear of Catalytic Converter.

Those position must be in the right spot to keep the Check engine lite off. Bank 1 Sensor 3 must show cleaners exhaust then Bank 1 Sensor 2 or the PCM will think the CAT is not cleaning the exhaust like it should. In the 97 you can have the non-primary sensor set to "do not report" if you can still find someone to do it. The 97 was the first year that programming worked pretty good. A common upgrade for a 96 was to replace the PCM with an unlocked 97 PCM. The PCM where about the same just the 96 re-programming was glitchy.

 

Ok, I'll have to look and see if I can find the wire for the RH manifold. It took me awhile to find the left, so the one I found on the RH side must be for the before and after CAT O2 sensors. That's just what makes the most sense, I'm pretty sure the y-pipe I took off was not modified, that it is factory original and the header I bought have the before CAT O2 bung in the same place.

That is the upstream and there would have to be a down stream.

I bet I just did not look well enough and when the weather is better I still have the car on jack stands and I bet I find the square 4 wire plug for the RH manifold that I just did not see before.

Thank you everyone!

 

Does anyone know the OEM part#'s for all four O2 sensors, or can someone link me to the correct parts for all four sensors?

One in each manifold( should be upstream )?
One before the Cat in the Y-Pipe ( should be the same as the manifold sensors )?
One down stream just after the cat( this one should be a Wideband sensor)?

Also I found the other 4 wire connector for the downstream, but I'm going to need an extension wire to reach it as it's very short right up on the upper right firewall. Adding an extension won't affect the readings of the PCM will it?

I assume not as it must have had one from the factory someone discarded when the cut the exhaust off from in front of the cat back.

One last thing, anyone have any experience with the universal high flow Catalytic converters?

I ordered a cheap one from eBay and I'm hoping it won't set off the MIL on the downstream O2 sensor.

 

rock auto has a good search engine and have choices for brand. looks like they is all the same. https://www.rockauto.com/en/catalog/...2)+sensor,5132