I’ve got an 01 XJ and I would like to chuck the stock exhaust manifold (which has a small leak) to the weeds and upgrade to an OBX or Pacesetter header.


Unfortunately my 01 is Cali- compliant and has the pre-cats and 4 O2 sensors.


Now, as I understand it, since my vehicle is over 8 years old and has over 80 thousand miles on the clock and there is a legitimate reason to do the swap (leak in stock manifold and the heat soak problem with the number 3 cylinder that is common in this year) there should be no legal reason that I cannot do this.

I plan to re-install the first 2 O2 sensors that the computer uses to adjust the air/fuel mix and use an O2 sensor simulator on the one after the pre-cats and re-install the O2 sensor that goes after the actual catalytic converter (which I plan to replace with a high flow cat)

Does this sound doable? Any info / suggestions would be appreciated

 

sounds like it will work but id just weld the crack... the manifolds flow fine unless you do head work. wouldnt see much gain without full porting.

let me know how it turns out because i have extensive head work done and could benifit from a set up like this.

 

I'm interested in how this turned out, or if anyone else has done something like it. I'll be putting a header system on my '01 soon. My Jeep has two O2 sensors before the pre cats and 2 directly after the pre cats, all in the Y-pipe. I don't remember seeing any back by the main cat. Since this is my first ever "modern" engine rebuild (all my others were carbureted and pre-1980s) I don't know much about the computer stuff.

What needs to be done if I install a full-length or shorty headers? Can I put O2 simulators on both the downstream sensors? How do those work?

 

Maybe I don't understand this cause I'm from Canada, but why would it be illegal to replace your manifold without a good reason? Same with a catalytic converter. I installed a cat back exhaust system less than a year after getting exhaust work done to the jeep. Why should a performance cat or headers be illegal?

 

I don't believe putting on a new cat or exhaust is illegal, just removing them completely

 

I read a link on this website saying it is illegal to replace it without a valid reason. However, it is possible I misread or misunderstood it

 

youre not supposed to remove a catalytic converter. In new york state if the check engine light is on on a 96 and newer vehicle it automatically fails the annual inspection. on a vehicle newer than 25yrs old up to a 95 they do a visual check to make sure all the emmisions stuff is there. you can replace exhaust components as long as you keep a cat and your modifications dont trip your check engine light. That prolly doesnt help the OP but thats how we do it here in NY.

 

US code states that it is illegal to modify the emissions system on any vehicle that is less than 8 years old and has less than 80k on the clock.
Even then there are minimum requirements that must be met.
I think it’s a stupid law, but it is the law.

And any talk of doing anything with a catalytic on here, or any automotive forum, could get you in trouble, so I wanted to make it clear that I knew the federal guidelines and had every intention of following them.