now that i read the WHOLE post, the cat being welded up may mean it is gutted. the cracker headed will ruin a cat, add a bad O2 sensor to the equation and the cat is a goner.
i would replace the header, or at least do a temp repair to troubleshoot the O2 sensor. The extra air the crack in the header sucks in causes the O2 sensor to report a lean condition to the PCM. The PCM enriches the fuel mixture, causing it to run rich, killing the cat. Of couse, This is all dependent on the health of the O2 sensor, which is an unknown in your case.
Right now the ZJ is totally stock. Tires, wheels, every thing. For now any way.
My plan at this point is this:
Replace cracked header with new one. (Not sure what to buy yet, little help here?)
Replace injectors with 703 Neon injectors. (Knew about this and was planing it already.)
Replace up stream O2 sensor. (Current one looks to be stock. Jeep has 152k on it)
Replace failing fan clutch and fan with electric fan from 99 GC, and a fan controller.
Replace drive belt.
Do a compression test.
Test fuel pressure.
Check for vacuum leaks.
Change oil and filter.
Change oil in both diffs and replace leaking cover seals.
Change oil in T-case.
Replace leaking rear wheel seals and install new wheel bearings while I'm in there.
Replace leaking real main seal.
Replace leaking valve cover gasket.
Replace leaking oil pan gasket.
Replace leaking oil filter adapter seal.
Attempt to force the ECU to throw a CEL by unhooking engine temp sensor to be sure that the CEL circuit in the ECU is working. (Have been told Jeeps have a problem with this, and not throwing a CEL or code even when there is a problem.)
And I will look at relocating the AIT sensor as well. Why do people do this?
Where is it now? And will this work okay in extreme cold such as ND in January? Extreme hot such as NV desert in August? I ask because I may move at the end of the year, but I don't yet know where I will be going.
I understand that this thing is not going to do 0-60 in under 6 seconds. LOL
But stock it was rated to do 0-60 in just about 11 seconds. I would be happy with that. Right now I'm closer to 17 seconds, give or take a second.
And passing is just out of the question.
I will admit I am used to driving a much faster car then this is. But I have owned slower cars before. And its not a problem. As long as they run right.
My current DD is a highly moded WRX pushing about 460hp at the crank.
I don't expect the Jeep will ever keep up with it. LOL
But I do expect I can at least keep up with my sister driving a fully loaded Dodge Mini van pulling a trailer!
Yeah she smoked me, her and 4 kids, 2 big dogs, and bunch stuff for my brothers baby shower, PULLING A 1,400lb TRAILER!!!!!!!!!!!!!!!!!!!!!!
She drives like that mini van is a sports car. I was trying to follow her and had to call her and tell her to slow down or she was going to lose me. I could not keep with her in the city, or on the high way. (She was doing like 90mph on the high way with the trailer!!!! Yeah shes nuts!
If what I have planed dos not fix my problem where should go from there?
I have herd that there is a TSB for the ECU not throwing codes. Is this true?
And is there any thing I left off my list that I should just do?
Thanks for the help guys!