exhaust

Hey all I have a 00 xj with the mini cats on the exhaust pipe coming off the manifolds. I'm wondering if it's possiable to replace that pipe with the mini cats with a standerd non california pipe the only thing that would need to be done is too weld another bung for the 2nd o2 sensor in the pipe on the side without 1,I would still have the main cat in it,and this xj is in upstate ny so the one cat is enough what do you guy think any down side to this thanks.arty::us:

My 2000 has the same thing and I'm from CT. You would either need a PCM and wiring from a non-Cali emissions jeep or use those fake O2 sensors. They are made to fake the computer into getting a good reading. Not sure exactly where you would find them. The non-Cali emissions Jeeps have 2 O2 sensors where the California emissions jeeps have 4 sensors. I looked into it with mine, since those pre-cats create a lot of heat build up under the hood, but it looked like more work than its worth.

If you do emissions testing, you'd also have to check with them as far as requirements and switching it over. I know in some states they do the testing based on the requirements for that specific vehicle when it was manufactured.

On my xj I have the two o2 sensors just after the mini cats 1 in each pipe and thats it, where are your other two o2 sensors located at, I also have the site for the fake o2s.

Check with your state regarding modifying any emissions equipment.

Simply welding in two extra O2 bungs and removing the cats will cause the CEL to come on.

maxwedge said:

On my xj I have the two o2 sensors just after the mini cats 1 in each pipe and thats it, where are your other two o2 sensors located at, I also have the site for the fake o2s.

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I'm not sure exactly where they are, but I was told theres one before and after each mini cat on the manifold. I was getting crappy mpg a little while ago and thought about replacing the O2 sensors. Every place I went to said mine had four including the stealership. Thats when I looked under it and realized I had the mini cats. I'd look now but its dark out. I'll see if I can find them tomorrow. The bad mpg ended up being a combination of small things.

Talyn said:

Simply welding in two extra O2 bungs and removing the cats will cause the CEL to come on.

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x2. another reason I didnt do it. The PCM gets readings from those sensors and adjusts the mixture on warm up. The whole point of the pre-cats is to cut down on start up emissions. This is why on my 2000 the exhaust is much quieter on start up than my previous cherokees. Once warmed up it gets louder. Theoretically those fake sensors should work, but I don't know for sure.

The after cat o2 sensor have nothing to do with the AFR. They just check to see if the mini cats are functioning. The PCM monitors no O2 sensors during warm up.

Last I knew, NY was a CA emissions state. Many states have adopted CA emissions for their regs as well. When we bought our little Geo Tracker before moving out of NY it came with CA emissions. Be sure that NY doesn't follow CA emissions, and also read the Federal law regarding modifying your emissions control systems. When Fed and State disagree, the stricter law takes precedence.

I have the same setup in my 2000 ...the underhood sticker says the vehicle is classified by the EPA as an LEV ....Low Emissions Vehicle. Mine started life up in the Northeast where apparently many of those states have adopted California emissions standards. My dreams of installing a good aftermarket header are just that.

My guess is that you would probably trigger a CEL light and your engine would probably not run very well. Each "mini cat" has a set of O2 sensors; one before and one after each cat. The setup is "close coupled" to the engine and designed to respond much quicker to changes in exhaust composition (tighter reign on fuel mixture) than the typical downstream cat.

You might have some luck swapping the ECM with that of a non-LEV emissioned vehicle but that seems like a lot of work ...and you still may have problems. But the bottom line is what the legal ramifications are for altering the factory emissions equipment on your vehicle.

Mike '00"LEV"XJ

There are a few companies making a header for the 00+ cali vehicles. Rugged Ridge is one that comes to mind.