Hey guys.

So a little background on my XJ 99. I really only use it to go mudding and it does take quite a beating, but I maintain it as well as I can. As I was driving it yesterday on a normal load, I started feeling some weird things.

As I drove about 10 minutes into my drive, at a constant speed of 45MPH, the jeep would start to sputter and it almost seemed as if it were running out of gas (I have 1/2 tank). I put it into neutral, gave it a big throttle press, then it was fine but then 5 minutes it did it again. Another 10 minutes into the drive, I felt a kick in the tranny...Almost felt as I got hit! As I come to a stop at the light, the RPM's would go from 800-1200 then shut off.

This all starting happening when I changed both drive shafts this weekend. I know this doesn't have anything to do with it, but just find it funny.

Since January, I've changed spark plugs, wires, dis cap, alternator, starter, battery, valve cover gasket.

Any ideas where to check?

 

haha, this is something i had been dealing with for about 5 years. id say first check the o2 sensor function. chances are it needs to be replaced. but, do a little research first. you've thrown a lot of parts at in the hopes you'll find it. not that everything you've replaced wasn't in some way necessary/helpful, but it adds up. if it is the o2 sensor, get a good OEM one- 4-wire, preheated. other than that, fuel delivery is suspect. the symptoms you describe fit the bill for this issue. so maybe a bad pump is the problem. unfortunately in our 99's its an in tank unit, so a bit more labor intensive, but at least you can inspect the gas tank for crud.

heres where the fun starts. if all else fails, theres a chance you've got an issue with the PCM, or ECU, or ECM, or whatever ya wanna call it. either way, these units are exposed to all elements and a fair mount of vibration and are prone to failure. i had to replace mine recently and was quoted at 1000 bucks for the part, no install (which take all of a minute) because it was a "discontinued item.. well i ended up paying about 240 for a refurbished one from the internet.. hope its the o2!

 

clogged fuel filter? thats about what mine did to me

 

this ended up being part of my problem. idk how that much crap got into my tank- sand, mud, leaves.. wtf?

 

Thanks for the info! I will start looking tonight!

 

Have you checked the fuel pressure at the fuel rail with a mechanical pressure gauge? You should have 49psi +or- 5psi.

 

So far today, I connected the computer to the OBD and threw codes p0132 and 0138 which I suspected because when I bought it in January, the prior owner told me that the O2 sensors were bad.

 

so you knew the o2s were bad??

 

Hhahahahahaha That's awesome!!!!

 

thank you for seeing the humor in it hope its an easy fix!

 

I will change those tonight and give you an update tomorrow!
Thanks again. I really hope this solves it.

 

i'm not trying to hijack the thread but i have a 96 i just picked up and at least one of the o2 sensors is bad. my scanner picked up the same obdii code. i'm still working on getting her road ready so i haven't driven her much but a bad o2 sensors can cause this much trouble? i had a corolla with a bad o2 sensor and i drove it for months. only noticeable difference was the gas milage decreased a bit.

 

Everything's different.. I'd expect different results for different cars. Also, could have been a different issue or a different o2- the ones toward end of exhaust can cause similar.. Iirc..

 

Here's a great one I got for you..... I just went out to the jeep to look at the o2 sensor and the see it in the exhaust/header.... As I follow the wires to see the location of the plug.....what do you know!!!! It's not even plugged in... I see the end of the o2 sensor ziptied to my shock... I look now in the engine bay and I see the other end of the sensor which leads into( what I believe is the fuel rail) not attached... So is it as simple as connecting them??

Do you see any reason why they weren't connected in the first place?

 

Ziptied to the shocK!?
Looks like someone maybe was planning to remove them, didnt succeed (they can be a pain to remove) and left it with that.
Try reconnecting, you've got nothing to loose...
But I'd go ahead and replace them, G knows what the history is with them now...