nickanicus

I just bought my first Jeep. 01' 4x4 with 153k. Fairly clean and no rust, but I have to sort out a dilemma with the exhaust setup. At some point in the vehicles past, a previous owner had put a different engine in it. It was apparently from before the coilpack era, and there is apparently a head casting difference that makes the factory 01' manifolds not work. They went with a pacesetter/ebay/whatever header setup that fits fairly poorly and lacks precats, normal cat, or the provisions for the two rear oxygen sensors.

I didn't realize getting into it that the jeep was that kludged. What are my options to retain some sort of decent fuel mileage and not have the check engine light on?

As I see it, I'd have to get a new cylinder head, factory manifolds, precats, and a cat in order to fix things properly. Any other thoughts?

Thanks guys, I think I'm going to enjoy this vehicle once I get these issues ironed out.

XJRed96

Adding a Cat and O2 sensors to an exhaust is not difficult at all. It's a matter of welding in bung holes for the 2 O2s and then buying a Cat (preferably free flowing since you have the option of choosing). If you do not have access to a welder or feel that it is beyond your skill set then bring it to a "Juarez and Son" muffler shop and have them do it. the only difficulty now is figuring out what year the engine is and what kind of ECM is installed so that you can find compatible O2s. Also I see one other problem with that as well... are the original harnesses still in place for the O2s and are the harnesses properly connected to the ECM... considering you have an MIL on for what I am assuming is an "open in O2 circuit" it's probably in place... Your final option is to find some "dummy" O2's and just plug those into the O2 harness and fool the computer into thinking you have 2 properly working sensors and avoid the whole exhaust system modification as a whole.

volaredon

located where? (in case other members may have spares to help you get it going correctly)

nickanicus

In Orlando, FL. Looking at getting the factory cats and an aftermarket manifold to work together. If anyone has any of the 00-01' factory exhaust parts, I'd definitely be interested.

evan00xj

Ok
1- the fact they got rid of that oem cylinder head is good. Most of the 00-01 heads were prone to cracking. My 2000 jeeps engine has an older style HO head that has been ported out and has custom brackets for the coil pack

2- get rid of that pace setter crap. Its not gonna last and will probably leak/ crack

3- the 00-01 xjs had the pre cats so there are a total of 4 02 sensors. (Trust me on all this i just replaced all my cats, sensors,header, and manifold gasket)

nickanicus

I understand all this. I've researched it all extensively. The problem is that I dont see how to get a header/manifold on an older style motor (with the old style ports) that works with the new pre-cats and 4 O2s. As I understand it, the late 4.0 (2000+) cast iron manifolds dont work with the old HO cylinder heads.

volaredon

I had an 01 XJ (before my son put it on its roof in a ditch) and I am not saying that's wrong (having 4, O2s) but I dont remember it having that many; I remember replacing 1 during the years we had that XJ. (I know it had at least 2)

I have a pair of precats and the cast iron "half manifolds" (cast iron and each was a 3 cylinder manifold) off of an 00-01 TJ (1 year or the other, don't remember which)
Bought from Feebay 7-8 years ago for I dont remember what, and been in the attic since. Not new but IIRC only like 15K miles was supposed to be good cats.
shipping probably will be prohibitive from IL.

volaredon

whether they work with the old style heads or not IDK about; but since so many people like to put the 99+ intake manifold onto older engines if the intake fits I don't see why the older header-manifold wont work as well.. (not saying it will/won't)

IIRC the plan at the time I got the cast iron ones I was gonna replace the cracked OEM header either on that XJ or on my 97 TJ with that setup and wound up welding up the cracks and reinstalling the header.
Both my current 97 XJ (replaced the rolled 01 XJ 3 years ago) and my 97 TJ (owned since Y2K) I have had to pull the headers from and weld up; the TJ is 6-7 years since, the 97 XJ is 2 years since I did this and so far neither has re cracked.... neither cost me more than a couple hours time and a manifold gasket. (I have my own MIG)

evan00xj

Ok so your saying you have a 2001 block but it has the older cylinder head, and the older intake manifold. (98 and older) wow

evan00xj

If thats the case just go to the jy or someone parting out a 99 + model and take the intake manifold.

northline76

I have a rebuilt 2001 head and an extra 99 and up intake manifold laying around if your interested send me a pm.