CAT O2 Sensor

Ok.. not sure if this is a mod tech or OEM but I', asking here.

Recently had the O2 sensor on the cat crushed against the belly of the jeep. And now it needs replaced.
I am wondering if anyone else has gone thru this and what they have done in order to prevent it from happeninh again. Relocated it, removed it?
I have the a '97 and it does have 2 sensors, second loacted at the muffler end of the cat (on the top)... just wanna get that out there before anyone tells me I only have one.


thanks

Re-Tread

Check out Cherokee Nation. He's got a skid that goes all the way across the belly of the XJ and it should be what you're looking for.

:wstupid: Don't mind this post,I screwed up and double posted somehow

Is there a link to the cherokee nation site? I'm interested in a belly skid too.

Thks
Scott S.

a skid.. thats all the advice that can be found here? wow.

Rufies97XJ said:

a skid.. thats all the advice that can be found here? wow.

Click to expand...

Thats because it's the best advise. You can't remove the o2 sensor because it will set your check engine light. The rear o2 sensor is used for catalyst monitoring. If the cat is hollow (or not working), the rear o2 sensor reads the same readings as the front, sweeping from .2-.8 volts as it goes rich-lean-rich-lean trying to stay stoichiometric. When the catalyst is functioning properly, the oxygen content (which is consumed when changing carbon monoxide [CO] into carbon dioxide [CO2], and hydrocarbons [HCs] into water [H2O]) does not vary so the voltage from the o2 sensor stays the close to the same voltage.

Another option for a solution would be to relocate it. Do you have fab skills? If so, you can buy weld in bungs. Take off your cat and put your o2 somewhere else. It sill must be downstream of the cat, and close to the cat, because it needs to stay hot.

By the time you spent $ for whatever fix you decide to do, you might as well have bought or built a skid. The fact is, that you asked for a solution to your crushed o2 sensor problem, and a skid is the best solution. It's like saying 'Hey, I keep hitting my t-case on rocks and cracking the housing, but I don't want to put a skid plate on, I want another solution". That solution would be to upgrade to a cast iron case (that may solve the problem) or skid plate. What answers are you looking for?

Steve

Thank Steve.. I was looking for more than "put a skid on it"
I don't have the money for a skid or I would have done that in the first place.
You have made a great suggestion and it was the one question I was hoping someone could answer.. and Yes. I did ask it.
Now my new question... how close doe the sensor have to stay to the rear of the cat? You said something about heat... so if I were to get a bung and relocate it... can it be anywhere in between the cat and muffler? More parallel to the body, instead of perpendicular as it is now.
Thanks Steve...


Re-Tread

well, a skid is defintely the best option,
you can also get a bung and just rotate the sensor around out of the wya...try to keep it as close to the cat as possible.
thirdly, if you wanted to just eliminate the 02 sensor all together, you could just get an o2 simm, but they are like 60-70 bucks, and at that point you could kill two birds with the skid
hth
~John

JohnBuuu said:

you could just get an o2 simm, but they are like 60-70 bucks,
~John

Click to expand...

Could ya explain this more. Please... never heard of such a thing.

Thanks!! re-tread

I don't feel that the skid is the best option. You're adding unecessary weight. Retread and I talked about relocating but were unsure as to what the inards of the cat looked like or how far downstream we could move it. He doesn't need fab skills, he's got me and my shop at his disposal I feel that moving the sensor is the best option. Your computer is still getting the correct readings and it won't get smashed between the floor and the cat anymore. I'm surprised we haven't had more discussions about this, maybe I just haven't paid attention.

Sean

Somewhere between the cat and muffler should be ok. Your cat's honey comb should end around the point it starts to taper down to the pipe diameter. I'd keep it within 6-8 inches of the begining of the taper. I know of hot rodders that have built a rear o2 sensor elimiator. They used resistors and such and created what you called an "o2 simm". I have never hear of a production unit, but makes sence that such a thing exists (I really doubt all those ricers run cats). I'd assume there would be one for the pre-cat o2 and a different one for the post-cat o2, since they work differently??? That is an option, and since the post-cat o2 only monitors catalyst efficiency, it will have nothing to do with your runability.

Steve

J

Rufies97XJ said:

Could ya explain this more. Please... never heard of such a thing.

Thanks!! re-tread

Click to expand...

sure...all it is a little plastic doo dad you plug into the harness where the rear 02 sensor goes. it simply sends the voltage to the computer that a functioning rear o2 sensor would send, if the cat/or o2 sensor, depending on what you removed, was still intact.
theyre big with the domestic muscle crowd, cause you can cat delete, and prevent computer codes.
i will say ive never seen anyone put on on an XJ personally, but i see no reason it wont work.
that said, 60 min for 02 simms, but only a couple bucks for a new bung, id try that first.
i dont know how your XJ is setup or how you use it, so i really cant comment much more than a skid its always a welcome addition to the undercarriage party, and i would consider that option unless you have a specific reason you dont wanna run one...
just my opinion

~John

OneTonXJ said:

I don't feel that the skid is the best option. You're adding unecessary weight. Retread and I talked about relocating but were unsure as to what the inards of the cat looked like or how far downstream we could move it. He doesn't need fab skills, he's got me and my shop at his disposal I feel that moving the sensor is the best option. Your computer is still getting the correct readings and it won't get smashed between the floor and the cat anymore. I'm surprised we haven't had more discussions about this, maybe I just haven't paid attention.

Sean

Click to expand...

thanks Sean...
I'll get the parts and we'll talk later.
Thanks Willis and John..
hope we can all learn from this!:anon:

not seen the newer ones but can you just rotate it up around the pipe and keep it the same distance from the cat? or is this not an option due to space?

rnmedic said:

not seen the newer ones but can you just rotate it up around the pipe and keep it the same distance from the cat? or is this not an option due to space?

Click to expand...

Can't rotate it... its on a flat spot and if it were to be rotated, the bung wouldn't fit on the radius.
I think we can move it a few inches towards the muffler and place it on the pipe.

Rufies97XJ said:

a skid.. thats all the advice that can be found here? wow.

Click to expand...

:looser: You're welcome!

Just an FYI: You won't lose any ground clearance (OK,maybe 3/16"-big woop! If you can't afford to lose 3/16" you need more lift) with the CN skid,as it's form fitted to wrap tightly around your x-member and bolts to the "frame" rails on the outsides.

Like I said before....

Rufies97XJ said:

I don't have the money for a skid or I would have done that in the first place.



Re-Tread

Click to expand...

that goes for the lift too.

We've figured out a solution.
Thanks again for your help.

Well,my whole point is cost vs. effectiveness.

Figure it this way and you'll see my point(or not,I may be way out of line,but I'm just trying to help). The cheapest that I could find a replacement O2 sensor for my wife's XJ was $80 with tax at Auto Zone (it was a Bosch brand). Now,I have complete faith in One Ton's fab skills,he's a master fabricator! But,*what if* something goes wrong and it happens again? Then you're out another $80. So,there's $160 out the door,when a good skid would've only cost you $140,and you'd get some much-needed underbelly protection,to boot. It's obvious that if you're crushing the exhaust system to the point of ruining the O2 sensor that some serious consideration to protection should be on the "to-do" list. Just my $.02

BTW,where is your O2 sensor's current position? My wife's was on the driver's side of the pipe,and it seems like it would take quite a bit to crush it :dunno:

Here's a link for whoever wanted it


http://xjnation.homestead.com/skidplates2.html

SOrry to sound like a smart@ss... bad day. I do understand what you are sayin... I am not against a skid... but I need another fix other then a skid.
Anyway... my O2 sensor...the second one...is on TOP ( :dunno: ) of the cat at the end...on the muffler end.

I have to replace the sensor now..so $80 out the door... (again... just replaced the exhuast system and both O2 sensors 6 months ago) so.. relocating is best thing for me to do right now. most cost efficetive cure.

I do have a lift sitting in OneTon's shop... so clearance will not be an issue once I can get the rest of the lift.


Re-Tread

" Anyway... my O2 sensor...the second one...is on TOP ( :dunno: ) of the cat at the end...on the muffler end. "


That is weird! I guess DC may have had some issues with this in the past and that's why they moved it to the side? It doesn't even seem like it would have room to fit on the top of the pipe,but then again,it's been a while since I *really* looked at the wife's sensor. Hers is mounted on the driver's side of the pipe(as previously mentioned),so it would take some serious pounding to crush it against the floor boards. Anyway,glad to see you guys have it figured out! :thumbup:

P.S.-About the "Smart-ass" thing,don't sweat it! We ALL have those days I don't think anyone's immune to them