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Let us know what the actual codes are. We might be able to help you save time and money and prevent the unnecessary replacement of parts. Although you could have a faulty O2 sensor, usually an O2 code is indicative of some other problem. A trouble code does not mean that a part is bad. It just gives you an idea where to start. There are dedicated test procedures for each code. We don't want you to replace a part just because it might be bad. We want you to know for sure that you are taking steps in the right direction. Some of the parts counter pros know their stuff (retired technicians). Some of them are cashiers that happen to have access to a code reader and will lead you lost as well as broke.

Post back with more info or questions. We'll be glad to help. Thanks

when i first start it up i

Submitted by fredneckj on Thu, 02/02/2012 - 09:30.

when i first start it up i have to let it idle for a couple minutes. about 3 mins it starts to act like it's gona stall. you can hear the rps go up and down if your outside you can hear it sucking air like it's sucking through a straw. after about a min or 2 it's starts to run normally. if i start to drive it before i let it do this, after a mile or so, it will lurch like i'm runnig out of gas. again the rps rise and fall. sometimes wil will make a poping sound. then it runs normally. this happens only after start up. motor was replaced a couple weeks ago. i've had it back but it's not being fixed. i don't know if the too are related. the check engine light came on so i took it to autozone. the print out they gave me said HO2S12 circuit condition (heated oxygen sensor bank 1 sensor 2). explantion 1)oxygen sensor defective.that could have something to do with why i had motor replaced(25lbs compression on 2 cylinders). 2)fuel system running very rich or lean-check other codes first 3)engime misfire conition-repair 4)fuel pressure very high or low-fuel pump or pressure regulator.if HO2S12 isn't code i can go back and get it. thank you

Fred (You Said) checked at

Submitted by Big Block 409 on Wed, 02/01/2012 - 04:46.

Fred

(You Said) checked at auto zone. first of 4 probabilities

First of 4 probabilities of WHAT. What EXACTLY is the problem?

Tell us what driveability (and or performance) problems you a having?

Post the actual error code numbers that Auto Zone read for you.

I don't like the word probability, because it implies that the folks a Auto Zone are guessin at what causin your problem. It's your time and money here man, and guessin is not fair to you.

How's it goin Fred?

Submitted by Big Block 409 on Thu, 02/02/2012 - 06:59.

How's it goin Fred?

when i first start it up i

Submitted by fredneckj on Thu, 02/02/2012 - 09:21.

Fred, Look man, you’re last

Submitted by Big Block 409 on Thu, 02/02/2012 - 15:49.

Fred,

Look man, you’re last posting has a lot of information, but really say’s nothing. What you’re describin in your post could be caused from:

One or more cylinder or ignition misfires.
One or more engine vacuum leaks.
One or more exhaust system leaks.

or problems with fuel pressure, fuel volume, (and or fuel regulation).

Knowin the actual error code numbers that Auto Zone read for you could help, so with being said it’s in your own best interest to post those error code numbers, if you wanna get the Jeep up and running again. Remember man, (and obviously) we gotta ask questions because this is an online auto repair forum and we don’t have your Jeep in front of us to test. You gotta be our hands and eyes here and give us the feedback we need, so that we can help you. That feedback can only come from you in the form of answers to our questions, and results to our tests, so you gotta be sure you're postin accurate test results. There's alot of repair information to post about the problem you are describin, but guessin is a waste of your time and money, and master mechanics never guess. So with that being said, let's start with the simple and most obvious first, which is to to post the actual error code numbers that Auto Zone read for you. If necessary go to another Auto Zone store and have another scan done, and this time write the error code numbers down so you don't forget them, then post them here so we can see them.

HELP YOURSELF SO WE CAN HELP YOU !!!!

Fred, Thanks for posting

Submitted by drivability on Fri, 02/03/2012 - 23:48.

Fred,

Thanks for posting back. In addition to whats been posted, have you tried to isolate the "sucking through a straw" noise? You can use a mechanics stethoscope (with the probe removed) or even a 2 foot piece of hose to try and track it down.

Is the air inlet and filter factory?

Also, you don't have to use the "reply" feature. You can just use "post new answer". It can make it easier to track your progress. We will normally know what or who you are addressing. If not, we'll ask. Thanks.