Delete the cats or not?

Fishtaco

Fishtaco

TJ Expert
Joined
Sep 29, 2020
Messages
3,761
Location
Perth AU
In my part of the world we dont have to smog test or any test! we just get a work order if cops decide to give a defect notice on a traffic stop.
Question is given my 02 sensor problem should I just delete the CATs? any experience with this?

Cheers
 
Because your 02 sensor's are so tied into your jeeps engine operation system, I dont believe you can delete them without causing serious issues with your pcm performance.
 
  • Like
Reactions: Hopper and jeepguy03
Tomcat said:
Because your 02 sensor's are so tied into your jeeps engine operation system, I dont believe you can delete them without causing serious issues with your pcm performance.
Click to expand...

If the Cat converters and O2 sensors are bad, replace them. Your Jeep will run better. O2 sensors are like $15.
 
  • Like
Reactions: Tomcat
If you remove the cats then you'll have to do something to trick your rear o2 sensor into thinking they're still installed, otherwise you'll have a perpetual check engine light. I don't think its worth the hassle.
 
Technically it's a federal crime to remove...(even tamper) with a Cat.

Obviously the swat team won't chopper in the moment your Sawzall comes to a stop but why hack on this thing to begin with?

I don't quite understand what you're trying to accomplish
 
You can remove the rearmost cat without trouble from what I've read (never done it myself). But the pre-cats on the downpipe should not be deleted. If you're worried about O2 sensors, then you are worried about pre-cats since there are no O2 sensors after the rearmost cat, just between the pre-cats and rearmost cat (at least on my 2001).

Whether or not it is legal or you'll find anyone who cares enough to give you a hassle, I don't know.
 
  • Like
Reactions: jeepguy03
The federal cops might have a hard time reaching him in Australia.

On a '98 you can remove the cat with no issues from the computer. Different years have different setups though so I have no input there.
 
Chris said:
I’ve deleted mine on two of my TJs.
Click to expand...
Since you have a later model TJ I assume the cats you deleted were the downstream (3rd) cat before the muffler on the later ones (2000 and newer). This cat doesn't have a sensor after it so deleting it won't cause issues with the PCM. Getting rid of the manifold cats will though.
 
  • Like
Reactions: Rubicon88
Skylinessuck said:
The federal cops might have a hard time reaching him in Australia.

On a '98 you can remove the cat with no issues from the computer. Different years have different setups though so I have no input there.
Click to expand...

If you remove the cat on a '98 you will (should) get a check engine light, since there is a O2 sensor downstream from the cat. I know on my 98 there is.
 
Chris said:
I’ve deleted mine on two of my TJs.
Click to expand...
I've done the same on some M3s of mine, I had to install a repeater to trick the ECU into seeing a signal so the MIL wouldn't come on. Is the same thing done on TJs or is there a way to mess with the PCM logic?
 
  • Like
Reactions: Chris
Rubicon88 said:
Ok??
Click to expand...

I thought you’d never ask 😉

jeepguy03 said:
Since you have a later model TJ I assume the cats you deleted were the downstream (3rd) cat before the muffler on the later ones (2000 and newer). This cat doesn't have a sensor after it so deleting it won't cause issues with the PCM. Getting rid of the manifold cats will though.
Click to expand...

On the last one I deleted the third cat, on my current one I am deleting all three cats. Once removed I just use HPTuners to disable the post cat O2 sensors which will make it so it runs great and no CEL or error codes are triggered. I am also installing full long tube headers at the same time.

It’s very easy to remove all the cats, but if you live in a place with emissions or inspections, you won’t pass. We don’t have that here.

I also love the way they smell without cats. Reminds me of my 69 Camaro.

I should also point out that while this is technically illegal, I don’t care what you do or what you don’t do with your Jeep, it is your Jeep after all. Just make sure that you’re aware that you won’t pass emissions or inspections if your state has it.

The 00-06 models are particularly restricted with THREE cats whereas the earlier models only had one.
 
  • Like
Reactions: jeepguy03 and qslim
qslim said:
I've done the same on some M3s of mine, I had to install a repeater to trick the ECU into seeing a signal so the MIL wouldn't come on. Is the same thing done on TJs or is there a way to mess with the PCM logic?
Click to expand...

I actually explain it in detail in my HPTuners review thread. It’s very easy to do. No check engine codes or lights either.
 
Top Bottom
Back