Mr.JayDeeM

I am experiencing some hesitation and bucking today out of the blue.

This is on my 2000 Xj with 186,000 at the clock and auto transmission. Out of the blue while driving it would buckle a tad and then at stop light at idle it would hesitate but not enough to stall it out.

I remember earlier I had to get gas. So I was wondering maybe water got into the gas while pumping it. I will try a bottle of HEET.

Another thing I could think of is the coil pack. It never been replaced told by a previous owner who is 9 years of ownership. How long does a orginal coil pack last before failing?

Does anyone have experience or input.

98cherokeeguy

Mabey a cracked dist

VTJeep

I'd guess the bank 2 o2 sensor. Get it on a code reader. Even if the CEL didn't trip, there might be something stored in there. But this does sound like an o2 issue. And if you do one, ya might as well do both...

Mr.JayDeeM

I dont have a dist, I have coil packs.

This is true. My light never came on.

98cherokeeguy

Haha yes your right haha did read where it said it was a 2000 xj my bad man
Well it could be a bad coil pack

Mr.JayDeeM

As soon this problem came up, I spoke to the guy who owned it for 9 years and asked about the coil packs. He never replaced it. Figured it related to fuel and air when it comes to hesitation and etc.

Mr.JayDeeM

Here's what I noticed today. Cold start, it stumples a lot then after when it get hot, it kinda goes away and smoother idle. That leads me thinking maybe the spark plugs? I know the previous owner put e3 plugs in. Maybe those are Crap. I know Jeeps like champion coppers.

supermini99

Maybe your MAP sensor?

Gee oh Dee

O2 sensor.

Check your codes. Parts stores do it for free.

VTJeep

x3'or 4... Idk I'm bad at math...

Mr.JayDeeM

I checked for codes and nothing came up at all. So I put new champions spark plugs and it seem like to help a little.

94XjSport94

I think i have the same thing as you right now minus the difference for cold and hot engine but i replaced the TPS senor today and still doesnt work i have no idea what to do next i guess o2

VTJeep

Well, if ya haven't gotten it on a code reader to make sure, even if CEL isn't on, then it's all potentially money wasted.. My 02..

94XjSport94

No one around here does OBD 1 scanners and if they do itll be another days wait and some unholy $ amount. i used the key turn method and got the code this way

VIKING3500

mine is a 90. I had bucking issues and I replaced plugs, wires, o2 sensor, tps, iat, and a few things I've since forgotten. The two things I think took care of it for me were replacing some worn grounds, replacing batt connections and wire brushing batt terminals, and replacing vac lines. I read up a lot on it and the vacuum leaks and poor ground connections seemed to produce those issues for a lot of people. I'm no mechanic so I hope I don't stir the pot here but it has helped my rig.