Catalytic Converter -
  • 3 Post By Timo_90xj
  • 1 Post By greers85
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post #1 of 5 Old 11-25-2021, 08:02 PM Thread Starter
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Catalytic Converter

I am in Texas where we have emission inspections each year. The way I understand it is that once a vehicle turns 25 then they no longer require it. I am in the process of building a 4.6 and by time I finish the ZJ will be 25. Is there anything specific I need to watch out for if I want to go back with no Cat? Computer issues and such? Also I am fine going back with a high flow cat if I have to. Just curious on the effect of deleting it.

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post #2 of 5 Old 11-25-2021, 11:58 PM
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I'm not from the USA, but as far as I know it's a federal regulation for all vehicles to have a cat converter if it came with one from the factory. I honestly see no issue with high-flow cat converters, they don't restrict exhaust flow that much and they keep the air we breath cleaner.
The converter cell in the 3" inlet-outlet Magnaflow converter I have in my 5.9 is about 4" long, and it passes our emissions test - about same requirements as Cali emissions - with flying colors. I've had the cat out at one point for other repairs, I felt zero difference in power with the converter removed.

If your Jeep is a '96-'98, do keep in mind the rear O2 sensor also slightly affects the A/F ratio; rear O2 sensor adjusts the so called goal voltage for the front O2 sensor.
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post #3 of 5 Old 11-26-2021, 08:00 AM Thread Starter
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Ok, that makes alot of sense and honestly what I was for. If there is a chance that it can affect engine management then I will just plan to go back with a high flow cat. Thanks!
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post #4 of 5 Old 11-26-2021, 09:41 PM
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Also, a reminder that, since it is never legal to remove emissions equipment at the federal level, the mods will shut down any thread that veers into discussion on removing the cat. If you want to get even more flow from your cat, you can always go bigger. On my 93 4.0 I installed a 3" cat (something like a 4 or 4.5 inch core) after the 2.5" cat (was a little smaller core) died. Just make sure you are actually getting a larger core than the regular 2.5" cat. High flow cats don't cost much power at stock Jeep horse powers.
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post #5 of 5 Old Yesterday, 07:21 AM Thread Starter
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Well then we are definitely not talking about removing it. This although a small post has been a wealth of knowledge. Thanks!
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