Getting codes for cat inefficiency so gonna bite the bullet and change out the precats with walker #52304 and since i'm at 160k miles (and had a cracked cylinder head and was burning a bunch of coolant) i figure i'll do o2 sensors as well (NGK #23099, 23110, 23506, 23151). It looks as tho no welding is required but i was curious if i need to get gaskets for where the cats connect (3 total) and should i get new bolts since the originals are pretty well rusted. if these are needed (and dont already come with the cats) what part #'s/size bolts should i look for?

another thing i was wondering is if clogged cats/fouled o2 sensors could be responsible for puttering on startup and rough idling.

thanks.

 

make sure you get oem sensors jeeps dont like aftermarket ones much

 

The NTKs were recommended to me, I assumed they were OEM or the closest to it

 

NTKs are OEM. Get em.

 

'00 XJ. Was getting the P0432. Just so happened that I needed a new muffler and tailpipe too. So I just replaced everything. Where the front dual cat connects to the exhaust manifolds you will want these:

4 of 6505754AA
4 of 6506546AA

I enclosed a picture of my old ones. They were in good shape, it turns out, but had no idea of that until I removed them. Still glad I bought the new hardware for that section of the exhaust anyway.

Now I am pretty sure that I used 3/8" stainless steel nuts, bolts, washers, and lock washers to connect the rear of the front cat to the front of the down pipe and rear of the down pipe to the front of the rear cat. Thing was is the hardware store did not have the proper length I needed so I bought longer and cut them down. Should be easy enough to figure out. Also since I bought a new muffler I need the nut to screw on the studs of the muffler to connect the rear of the rear cat to the muffler. Can't remember what size but think these were metric. One last thing. I bought a new Walker rear cat. 16117. The 3/8" bolts worked fine with it. I kind of remember playing with the factory rear cat and think the bolt diameter I used was too big to fit into the holes of the factory rear cat.

 

Perfect, exactly what I needed! much appreciated. Were there any gaskets you needed?

 

No doughnuts. 2 gaskets. Walker 31625.

https://www.napaonline.com/en/p/EXP31625

Between rear of front cat and front of down pipe and rear of down pipe to front of rear cat.

Other part numbers for you since I have my files out.
Insulator. Walker 35750. For the muffler.

https://www.napaonline.com/en/p/EXP35750

Down pipe. Walker 53440.

https://www.napaonline.com/en/p/EXP53440

Walker Quiet Flow. 21489.

https://www.napaonline.com/en/p/EXP21489

U-Bolt. BK 733-2217. Used one to attach tailpipe to hanger.

https://www.napaonline.com/en/p/BK_7332217

Tailpipe. Walker 55188. Will have to cut off rear hanger.

https://www.napaonline.com/en/p/EXP55188

Rear hanger. Walker 36377.

https://www.napaonline.com/en/p/EXP36377

Instead of using a U-bolt to connect the rear of the muffler and the front of the tailpipe I opted for this. BK 733-3972

https://www.napaonline.com/en/p/BK_7333972

Keep in mind I am trying to interpret all this from my files. You can probably buy all this stuff cheaper elsewhere. I got the exhaust manifold to front of front cat hardware from the Jeep dealership though. Might be able to source that somewhere else.

 

Thanks for the information, Ralph. Any tips on removing the old pre-cats from the exhaust manifold? I am also getting a code for inefficiency and need to replace the pre-cats, at least.

 

I did not do it. I just bought all the parts. I work at a Napa. Hacked off the old exhaust up to the front cat. Cleaned and POR 15'ed all the open area. Also put in new nut strips and hung a gas skid and the rear hanger for the exhaust. Drove it like that to a mechanic we do business with. Was afraid I would have trouble getting the bolts off. At the time I did not own an air compressor or air tools. Now I do. But was also a little worried about fighting with it on the ground. He charged me $75 to remove the front cat and hang all the new parts. He said they came out really easy though.

 

Yeah, that's pretty much how I feel about tackling this project. I haven't noticed any performance issues with the jeep so there was no immediate need to replace. But lately, it seems the CEL comes on more frequently.

I appreciate you taking the time to reply.

Matt

 

I am thinking it won't be that difficult but who knows for sure. Besides $75, was the friend and family price as far as I am concerned, was worth it to me to let somebody who knows way more then me handle it.

 

Take it out for a WOT blast and clear the code see if it ever returns, mine never did. It's worth a shot...

 

So looking at the Autozone page, under the Walker 52304 it says

"Ultra direct fit
EPA Ultra Converter. Front. Must Use Aftermarket Extensions Pipe 53440..."

Does that mean this won't fit with the OEM tailpipe? Not sure how it's "direct fit" if you have to get aftermarket parts for it to fit.

 

Read the reviews on Amazon. Possible issues with the O2 sensor bung needing relocated. Read the 1st question posted. There are 3 replies in total. They are 2 years old so things may have changed, but they are still worth noting. Aside from that i got nothing. Mine is a 97 so no precats.

 

Here is the diagram for a '01 XJ with CA emissions from Walker. Here is a diagram out of an official Jeep parts catalog for an '01. If you click on the Jeep parts catalog shot it will make it bigger to be able to read it. Now I can not say for sure how yours is set up. 53440 is the pipe between the front cat and the rear cat. Nothing to do with the tailpipe. What exactly are you replacing? I believe at one point in time from the factory 52304 and 53440 were both one pipe going into the rear cat. See what I circled. If that is the case with yours then if you are replacing the cat then you need to buy the other pipe. 53440. 53440 will bolt directly to your rear cat. You will have to get under there and look to see if the front cat is one long pipe to the rear cat. Or the cat, another separate pipe, and then the rear cat. Hope this helps.