[OkcViperTruck]

I purchased a 2005 RC recently and just noticed it does not have rear O2 sensors. The pipes appear to be 3 inch with high flow CATS and Magnaflow mufflers. One of the CATS is chattering, so when I inspected it I noticed no rear O2 sensors. Will this be a problem in the future when I replace the whole exhaust system? How do I re-install rear O2 sensors when it appears the wiring is gone? The truck runs great, but is very loud and backfires at decelaration. Thanks for any info.

 

[oldcolt]

The rear O2 sensors are used to detect faulty cats. The fronts are used for air/fuel. Who ever had your truck before must have had a tune installed to deleted the rear sensors. Have a look to see if there are any "sims" tucked up near the frame. If the wiring is gone, hopefully it is only the O2 leads and not gone from the harness. Backfiring or popping is normal on decal with these engines.

 

[OkcViperTruck]

I guess I'm going to need to find a wiring diagram for the sensor system.

 

[seethrough]

If you look on both sides of the transmission near the top you will find the wiring harness side of the O2 circuits with green (I think) connectors. As mentioned the plug will either be empty or will have an O2 simulator plugged into it. If the plug is empty and you want to add rear O2 sensors you will have to have the tune adjusted. If you are changing exhaust and want the rear sensors you can weld in O2 bungs.

 

[OkcViperTruck]

Well, I only saw the upstream sensors, and the wiring appeared to meet in the middle top of the trans then run toward a black box toward the middle of the truck. I found a photo on the net showing where the downstream harnesses are....looked like they are on either side of the smaller diameter section (rear) of the trans. I'm still looking for a wiring diagram for this truck, but having no luck. Thanks for the helpful info. As long as I keep it in Oklahoma, I don't have to worry about O2 sensors, as the state does not have annual inspections like the old days.

 

[ViperDad]

Maybe these will help:

http://www.srt10forum.com/forums/showthread.php?t=20715&highlight=service+manuals

 

[OkcViperTruck]

ViperDad, thanks for the diagrams. I basically forgot about this post. Actually, the previous owner removed the CATS. Like SeeThrough mentioned, there must be a tune on it. I'm hoping all the sensors and harnesses are still in tact, and that when I replace the whole exhaust system and CATS, that I can perhaps tune everything in. I bought this truck from a large dealer, so you would think that they would have disclosed the fact that the CATS were missing. I guess when you buy a used truck, it is as is.