Catalytic converter removal

[rockbottom]

What is the impact of removing the catalytic converter and replacing the exhaust system?
how do you deal with engine codes etc?

On a completely stock 2006 4.0 is it a good or bad idea?

Are there noticable performance improvements if you remove it?

 

[TJ Jim]

Remove the two closest to the engine and your computer won’t be able to control fuel.

 

[freedom_in_4low]

There are no noticeable improvements and it's doubtful you'd find anyone that makes what they're talking about to recommend removing them.

You can ditch the one next to the transmission without getting codes because the post-cat O2 sensors are upstream of it, but again, unless it's just clogged there's no benefit, and it'll be louder...better to just replace it if it needs replacing.

 

[97JadeTJ]

My prior 97 tj with a 2.5 in it had the rear cat removed when I bought it and it was obnoxiously loud… muffler shop put a cheap glass pack muffler in its place and it helped but the only way I could beat the check engine light was with a O2 fouler…. My new 97 tj with its 4.0 still has all cats and is considerably quieter and throws no codes!

 

[L J]

Are there noticable performance improvements if you remove it?

 

[P man]

Just leave everything in place it isn't worth the headache. I won't have a wrangler without a cat and a good exhaust system.

 

[Gilaguy23]

What is the impact of removing the catalytic converter and replacing the exhaust system?
how do you deal with engine codes etc?

On a completely stock 2006 4.0 is it a good or bad idea?

Are there noticable performance improvements if you remove it?

1. Putrid exhaust fumes
2.You dont
3.Bad idea
4. 0. Did I say 0 00000000000000000000000000000000000000000000000000000000000. You get the idea. Unless its plugged up or self disintegrated inside.

 

[rockbottom]

Thanks to all
I will follow the consensus of experiece

 

[jboswell11]

Thanks to all
I will follow the consensus of experiece

Unless, you have one of these in your exhaust... in which case fixing the problem will cause a gain in performance

That was most of my bank 2 precat as a biscuit in front of my third cat (the one by the t case).

 

[ChasUGC]

I can tell you this from my own experience. My cat was even recalled on my 1997 TJ. But, I replaced it before I found out. My Jeep kept losing power and it would completely stall. Black smoke would come out the back at times. If I let it sit for awhile, it would start up, because I guess the soot in the exhaust had settled. The dealership did all the service period maintenance, and it was slightly out of Warranty, so I had to pay for it. It cost between $2000-$3000. They even did a valve job. As I left the shop, it did the same thing. I was furious. So, I took it to a muffler shop around the corner from the dealership, and I mentioned that problem. I told the muffler shop that I hear noise underneath it, and the lose of power and stalling. So, the guy tapped the Cat. and it sounded like broken glass inside. My Cat. had collapsed internally and was blocking everything, like someone had put a banana in my tailpipe. He replaced my Cat. and the problem was completely solved. The Cat. on my 1997 was defective. I went to the dealership furious, that they wouldn't even check my Cat. when I told them about the noise. They just wanted to keep charging me. Eventually that dealership in Long Beach, Ca. went out of business.

 

[Jeepster97TJ]

I just stumbled on this thread doing some reading and I'm just wondering some things. I have A 97 4.0L 5sp. It has a header, exhaust pipe and muffler. No cats at all. It does have the O2 sensors in the front and one in the rear. I recently replaced the front one to fix some idiling trouble. Which totally fixed the idle rpms. Are there negatives to not having those cats? I have only had it since Nov 23 and have been doing minor things like tuneup, TB cleaning, IAC cleaning. This is my first Wrangler and I am learning the more I read but I read this and similar post about "no cat converter" and I'm not sure how long it has been that way. It runs good now though. Should I consider adding a cat or cats back in?

 

[MikeE024]

In my experience with a 2005, the exhaust fumes smelled bad and the loud exhaust sounded awful.

 

[Jeepster97TJ]

It's not really loud, maybe slightly deeper sounding than other Jeeps I've heard. As far as smell It doesn't seem especially bad, It doesn't seem worse than any of my other vehicles.

 

[MikeE024]

It's not really loud, maybe slightly deeper sounding than other Jeeps I've heard. As far as smell It doesn't seem especially bad, It doesn't seem worse than any of my other vehicles.

For my 2005, it smelled bad and the sound was awful. Your other vehicles shouldn't smell like hydrogen sulfide.

I currently run a 3" exhaust and the third cat has been removed for years, so it's not as if I can't handle some noise. Maybe the older style isn't as bad, but the gutted cats were no bueno for me otherwise they'd still be in that configuration for the turbo.

 

[macleanflood]

I put a Magnaflow 2.5 stainless cat on my 97. Love it. Made my own custom mid pipe to keep the exhaust tight to the pan and clear of the front driveshaft. Then wrapped it all up in DEI exhaust wrap to hide my shitty welds.

-Mac

 

[SkylinesSuck]

My '98's cat died a long time ago (only has one from the factory unlike newer models). While trying to figure out my loss of power, I discovered the exhaust clogged with cat honeycomb. I smashed it all out which gave me basically an empty shell, and drove it like that for 3-4 months until I got a new cat installed. Also just FYI I have a stroker motor. No CEL, no difference in power good or bad from normal, but it did noticably smell. I even had people comment at work that I smelled like gasoline or something a couple times because I was standing next to it idling before I came in. I think newer TJs with multiple cats are much more sensitive PCM-wise to having the cats removed.