Jgarland1987

So i've done a little research on here and haven't quite found my answer. I have a 99 xj with about 134k on it now and about two days ago it started rough idling and is stuttering some when you start to take off and sometimes tries to shut down whatever throttle you're giving it to take off. But it seems to clear up for the most part when you get up to speed or like this morning I gave it a few revs then it idled pretty well. It's never died and starts fine every time. The CEL has been on for some time now for the upstream O2 sensor but I haven't checked the codes since then.
Here's a short vid of the idle, I rev it a couple times over 1k but it'll give itself a little bump at idle.
http://youtu.be/dpwUjTSQm3U

97AT4x4XJ

Repair O2 sensor problem.

CCKen

If your O2 Sensors have 134K miles on them they're due replacement. Change both upstream and downstream at the same time. Suggest you use NTK sensors. That's who makes the OEM sensors. Try www.rockauto.com/ to get them.

Also, check the O2S Heaters fuse in the PDC. See image below.

97AT4x4XJ

I wouldn't replace bad downstream sensor.

Jgarland1987

Thanks all. I had a feeling that the o2 sensor could be causing this but I wasn't sure since when it first kicked on the CEL it didn't run any differently and i've neglected to change it for a month or so now.

Jgarland1987

Another question: There is a sensor with California emissions ($49.99) and one without ($62.99), what difference will that make besides the price?
Both are Bosch sensors at my local AutoZone.

CCKen

Some people have had luck with Bosch O2S', others have not.

You won't need CA sensors. The upstream and the downstream sensors are different part numbers.

Change both at the same time or you'll be back in there changing the downstream because of poor gas mileage and/or CEL on.

Jgarland1987

i would get those ntk's from rockauto but i need to get this done today or tomorrow, so local parts stores are my option right now. With a 1yr warranty i'll give'm a try

Jgarland1987

also the california emissions is cheaper. would there be a downside to using it?

freegdr

Checking codes is the first thing to be done, unless you just wanna replace parts untill you get lucky and fix the issue ....just saying...

CCKen

Don't know about CA emission O2S' except that there may be multiple upstream and multiple downstream sensors that have shorter pigtails.

Check that O2S heater fuse first.

Do like freegdr says and get the CEL code numbers before beginning.

Edit: I just checked my maintenance log and I see that mine were replaced at 129,977 miles. I couldn't get them out to save my **** so I took the Heep to a muffler shop and they used a torch to heat the bosses inorder to get them out. They charged me $35 a piece to change them (I supplied the NTK Sensors). It was worth every penny of the $70 to havethem do it.

Jgarland1987

Just found that the heated circuit fuse was blown. Replaced the fuse and that fixed the stutter. I'm guessing the sensor wasn't staying warm enough at low speeds and once you got it warmed up it was better. Gonna get the new sensor in tomorrow. The only codes showing were upstream o2 and heater circuit so at least those are my only problems

CCKen

The new fuse will buy you time to get some NTK sensors from Rockauto.