08jku w/ 80k miles 4wd 3.73 auto transmission

Recently noticed a sporadic issue when cruising around 40-50mph. Hard to explain but it feels like a studder or jerking. Doesn't make a noticeable sound but you can definitely feel it. I immediately thought it had to be transmission related because it kind of feels like the transmission kicking, maybe torque converter, but it's not "shuddering", more of a bucking as opposed to vibration . It happens both with OD on and off. Otherwise the Jeep shifts smoothly throughout gears both when I am hard on the pedal or easing through the gears. Seems to only happen when I am cruising or lightly accelerating. Than I thought it could be engine related, like a misfire or something. It's hard to tell and my CEL is not on nor do I show any codes on the dash or from my superchips programmer

I first noticed it after leaving a gas station, filled up with premium. Not sure if that had anything to do with it or if bad gas could cause it. . Also last week I changed my oil and ran some seafoam through the vacuum line (brake Booster). One strange thing is that when doing the seafoam, the Jeep started shaking a bit and making a ticking noise and the CEL blinked a few times. That hasn't happened in the past when seafoaming but the Jeep ran fine for days after that before I noticed the issue ..plugs and wires have maybe 15k miles on them (year old maybe). Not sure if maybe the seafoam could have fouled a plug or sensor. Starts and idles fine.

Any ideas? Sorry if my explanation is not the best.

 

Take a close look at transfer case

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What would I be looking for? Thanks!

 

Could be the fuel pump.

 

Had this happen with a bad tank of gas once, almost identical to your description. But recently had a similar incident turn into engine misfire and catastrophic blinking CEL of death appeared. New coil pack, plugs and wires at 78K. All is well.

Still need to get lower intake manifold gasket and possible oil pan gasket leaks fixed. Yikes.

 

Yeah I thought about that, I have a bad habit of waiting till I'm on E before filling up which I know is not great on the pump. No issues starting the Jeep though and it doesn't seem to happen more on incline which I would expect with a fuel pump issue.

 

I have my fingers crossed that maybe it's a bad tank of gas. I had filled up with premium which I always get because I have tuned my Jeep. Just in case it was a bad tank, I burned a quarter tank and topped it off with premium from another gas station and one of those fuel additive bottles. Don't think it made a difference but then again it was still three quarter tank of the original gas. I have gotten some slight pinging in the past which I attributed to bad gas but I have never had bad gas actually cause a noticeable kick

At this point I would welcome the CEL just so I could pull a code to know where to start.

 

I had very similar symptoms on my XJ a few years back, I didn't actually get any codes until it got bad enough to develop a full on misfire. Hopefully it was just bad gas, I have had that happen before as well.

 

Yea, the gas was bad enough that I had the death wobble shakes in 1st. Felt like I was driving stick for the first time. Ran a full tank through and was back to normal.

Couple days later, that same pump was out of service. Not sure if that was just coincidence.

 

A bad cat can also cause the issue you are describing.