Multiple codes and extreme power loss

[Kioti1]

Hey guys. Long time lurking but my first post. I did my due diligence and searched this first but wasn’t satisfied with what I found relating to my issue. I think I know the answer but I wanted to check with you experts!
My TJ is a 2004 X, 4.0L, Automatic.
Here is my issue
My son has been borrowing my Jeep for awhile. He said it seemed to be running rough with loss of power but no codes. I just recently got it back so today and my wife and I went on Sunday afternoon cruise. First hour and a half went great but then I started noticing a power loss and then extreme power loss. We limped the last 30 minutes home at best 30 mph. Checked codes as soon as I got home and I had P0432 - Below Threshold Bank 2 Cat, P0300 - Multiple Cylinder Misfire and P0303 - Clylinder 3 Misfire.
I assume it would be a bad Bank 2 Cat. Will that cause the other 2 codes since it was running so rough? Or did the misfires cause the P0432 code.
I’m in Georgia in a non-inspection county. Since the single lower cat is not monitored is removal or clean out an issue.
Thanks so much!

 

[macleanflood]

Pull some of your O2s out to create an exhaust leak and see if it runs better. Or use an IR thermometer to check exhaust temperature before, and at the CAT.

-Mac

 

[Kioti1]

Pull some of your O2s out to create an exhaust leak and see if it runs better. Or use an IR thermometer to check exhaust temperature before, and at the CAT.

-

Good idea
I’ll do that and report back

 

[Kioti1]

Pull some of your O2s out to create an exhaust leak and see if it runs better. Or use an IR thermometer to check exhaust temperature before, and at the CAT.

-Mac

Ok the cat seems substantially cooler than the manifold. I would think that it would be the other way around. I’ll try removing the upper O2 sensor on bank 2 when it cools down.

 

[Chris]

Ok the cat seems substantially cooler than the manifold. I would think that it would be the other way around. I’ll try removing the upper O2 sensor on bank 2 when it cools down.

If the cat is significantly cooler than the manifold, it might indicate that it’s not functioning properly, which could explain the codes and the power loss you’re experiencing. Removing the upper O2 sensor could give you a better idea of how the engine responds without the cat's influence.

Just be cautious while it's cooling down, and make sure to check for any exhaust leaks once you remove the sensor. If you see a noticeable difference in performance after that, it could help pinpoint the issue. Keep us updated on your findings! Good luck!

 

[Kioti1]

This afternoon was the first opportunity I had to work on it. I drove it first and it was still very much the same as Sunday with huge power loss. I then took out the upstream bank 2 O2 sensor and the power has returned. So I guess that means new precats.

That does bring up a new question. Which is the best option on the precats. I see some for $1300 and some for $200. One TJ guy recommended Flowmaster but I can’t find them on their website. Just want as good of a quality product as I can get without going cheap or spending too much.

The other issue that I will have is mine is welded from the precats to the tailpipe. No joints. And I’m not a welder!

Thanks for the great advice!

 

[MRChiefE7]

We just replace the pre-cats on our 05 LJ with a Magna flow 50899 from O'Reilly for $700.00 after a military discount. Power restored!

 

[Kioti1]

We just replace the pre-cats on our 05 LJ with a Magna flow 50899 from O'Reilly for $700.00 after a military discount. Power restored!

Yeah that’s the price range I have been seeing. Like to get out cheaper but I want quality and to not have to do this again in the near future

 

[Kioti1]

Ok new issue I hope you can help me with. Took the precats off today and new ones due in from Rockauto tomorrow with 4 new O2 sensors. Everything went great. Bank 2 precat was completely empty. Bank 1 was stopped up and the downstream cat was in pretty bad shape. I think it was my real problem. Anyway…..
I removed all 4 O2 sensors and was able to separate the plug on 3. On the bank 2 downstream sensor plug it seems that one of the Jeep’s previous owners must have damaged the clip and decided to epoxy it together. No way it’s coming apart. There is very little room to work against the firewall. The only option I can come up with is to cut and splice with the new O2 sensors. The problem is there are 2 white wires. No tracers are anything. The male side of the plug has unique colored wires but the O2 sensor side has a black wire, grey wire and 2 white wires. I have a 50/50 shot but I would like to get it right the first time. Any ideas?
Thanks

 

[macleanflood]

Wiring diagrams are in resources section under the Factory Service Manuals. Section 8w.

My guess is you already have a replacement connector and if you deloom more of the harness you'll find the splices.

-Mac