hey guys i'm relatively new to tweaking my truck with performance upgrades and was wondering what Cats and O2 sensors are for. I have a sideswept gibson exhaust and i just ordered Pacesetter headers which is why I'm curious because all i know is they deal with those two things. thanks!

 

any help would be much appreciated!

 

In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen.

The O2 sensors monitor the cats before and after

 

so what would be the point to taking the front O2 or back O2 sensors off? i've read about people doing that.

 

Guess they like the service engine light. No really I have no idea why you would take them off

 

Removing the front (pre-cat) O2 sensor will cause the engine to run like crap and KILL fuel mileage if it will run at all. This should never be removed to keep the engine running correctly.

Removing the rear (post-cat) sensor and replacing it with a simulator is done when any / all cats has been removed and the "check engine light" stays on in the dash. A good simulator will modulate the O2 readings just enough so the computer doesn't register a problem with the cat not doing its job, thus no light comes on in the dash. Basically it tricks the computer to think all is well with the cat when it isn't even there. As far as I know, the post cat O2 sensor is for monitoring the cat's performance ONLY. It does nothing in the way of performance.
(Those who know differently PLEASE feel free to correct me.)

 

You are correct, unlike the front O2, the PCM attempts no correction for a rear O2 error, it's simply a "nuisance" CEL.

I doubt anyone is pulling the front O2 as the truck will eventually go into limp mode if the situation is not corrected.

You can also do the $5 "non-fouler" trick when removing the rear sensor(s), it's a lot cheaper than the sims and works just as well...

 

Well I don't think I'm gonna mess with the O2 sensors. Thanks for all the help!

 

If you bought the Pacesetter Long Tubes you are going to have to. The headers will force you to have to either cut out the cats or move them back about 14" and if you keep the cats, you'll have to extend the O2 wires. Been there/done that...

 

I highly recommend that you do as Hammer said. The cats are a high flow design and the Hemi seems to like them on rather than off.