New exhaust cat delete???

[Squirrelsmith]

Whoever previously owned my tahoe bought the cheapest duel exhause they could and now its all rusted out.
I want to go new from the headers back. Since i have passed emissions for the last time (washington state no longer doing emissions... supposedly) i was thinking of skipping the cats.
Has anyone done this? Im wondering if the 02 sensor after the cats is going to throw a code

 

[drakon543]

yes the sensor after the cat will pick up on that and throw a code. however if someone wants to chime in and correct me if im wrong. that o2 sensors purpose is only for reading the cat not for engine adjustments. so you should be able to delete the cats and it will still run fine. when you get a chance go to a local tune shop and ask them to delete that o2 sensor. or while your there get a custom tune . i wouldn't think having just an o2 sensor deleted would cost much.

 

[BG1988]

yes the sensor after the cat will pick up on that and throw a code. however if someone wants to chime in and correct me if im wrong. that o2 sensors purpose is only for reading the cat not for engine adjustments. so you should be able to delete the cats and it will still run fine. when you get a chance go to a local tune shop and ask them to delete that o2 sensor. or while your there get a custom tune . i wouldn't think having just an o2 sensor deleted would cost much.

the engine mostly relies on the MAF and MAP sensors once the fuel is burned nothing really matters

 

[Big Mama]

What year and engine? Did it only have 1 sensor per side?

 

[bigfootchiro]

I’m having my exhaust custom made and no cats. Post O2 does not make any engine adjustments, but will throw a code. You can either run with a constant CEL or have it tuned out.

 

[iamdub]

As the others have said, deleting the cats won't affect the operation at all. The O2 sensor downstream of the cat is there only to monitor the efficiency of the cat. With it gone, you'll get a catalyst inefficiency DTC. It's up to you if you want to ignore it or have that turned off with a tune. Personally, I don't like having any warning lights on on my dash. If you constantly have an SES light on, you won't know if your engine develops other problems that would throw code(s) because the light is always already on.

I've heard of plenty of people having success with the spark plug non-fouler trick, so you can try that as a cheap and easy solution.

 

[Squirrelsmith]

I'm not into the idea enough to go down that path of codes and tunes. I'll just a put a high flow cat on there I suppose. Anyway the shop I wanted to go to said they won't do it and most in our area won't because if they get caught they will be executed in a satanic fashion (his words not mine)

 

[redwing4900]

I am kind of dealing with this issue with my 98Yukon. The after market exhaust needed replacement so I'm in the process of redoing it. I thought i was fixing a mixture problem the exhaust reaked of unburnt fuel...the cats were removed so my plan was to bring them back. Should i do this? I read in another forum that if the cats were removed and the O2 delete wasn't programmed in that it would cause the mixture to be like mine, way too rich. Is any of what i read true?

 

[iamdub]

I'm not into the idea enough to go down that path of codes and tunes. I'll just a put a high flow cat on there I suppose. Anyway the shop I wanted to go to said they won't do it and most in our area won't because if they get caught they will be executed in a satanic fashion (his words not mine)

Stock cat IS a "high-flow" cat. Most cheaper aftermarket cats don't contain the amount of catalyst that OEM cats do, and it's not uncommon to still get catalyst inefficiency codes from them.

 

[iamdub]

I am kind of dealing with this issue with my 98Yukon. The after market exhaust needed replacement so I'm in the process of redoing it. I thought i was fixing a mixture problem the exhaust reaked of unburnt fuel...the cats were removed so my plan was to bring them back. Should i do this? I read in another forum that if the cats were removed and the O2 delete wasn't programmed in that it would cause the mixture to be like mine, way too rich. Is any of what i read true?

Not true. The PCM doesn't adjust the fuel mixture regarding any input from the O2 sensor downstream of the cat. It can't do this because the exhaust that has been scrubbed by the catalyst can not give an accurate reading as to how the engine is running.

If your engine is running rich, it can clog the cats. Removing the cats will then let you smell the richness of the exhaust, completely unfiltered, but the running rich issue will have to be resolved regardless if you have cats or not. Rich exhaust can clog the O2 sensors upstream of the cats and those sensors DO affect the fuel/air mixture. If the sensors are clogged, they can report less emissions than what is actually passing, so the PCM thinks the exhaust is lean and it richens up the mixture to an already overly rich mixture, and it's a downward spiral from there.