So I know many write ups have been done on Jeep Wrangler JKU surging. But I've yet to read one that describes my particular case. I have a 2014 JKU Sport. 175k miles, but still runs strong, no major issues.
So I noticed this issue awhile back, probably been ongoing for about a year, when it started it was very subtle. Now it's every time I start and very noticeable. So here's my throttle surge issue, y'all tell me what you think...

1. Always happens when I first start up the Jeep... It's not during idle at all... Only happens when I'm motion.
2. During very light throttle, under 20 mph the motor feels like it's surging, that woah woah woah woah feeling, if that makes sense. It kinda makes the whole Jeep bounces just a tiny bit, literally like it wants to jump forward but never totally does.
3. Haven't noticed it after it's been running awhile. i.e. once it's warmed up. While going slow again.
4. If I give it just a tiny bit more throttle it stops for a second and then starts right back up.
5. I can kinda feel it when I'm normally driving if I am just barely touching the accelerator. It's very faint, but if you are trying to catch it you can feel it.

Things I've done recently with no change...
1. BBK big mouth throttle body2. Spark plugs3. Cool packs replaced with MSD Blaster coils4. Regeared from stock 3.21 to Yukon 4.56
5. AEV Pro Cal calibrated for gears and tires
After all this its still exactly the same... Perhaps there is another sensor I should be looking at getting replaced?
My CEL does comes on from time to time throwing a catalytic converter issue, I've replace all the O2 sensors and cleared the codes, but they come back after a few hundred miles... Could it be failing cats causing this? What would y'all recommend I check next? Thanks for the support. -Tony

 

What kind of codes you getting? There were no change in surge when you changed the coils and TB? When those old Ford Tempos gave trouble similar it was always the throttle position sensor faulty. But you have a new TB. Does the new position sensor match the stock Jeep one in resistance?

 

Your codes for the cats could be just that they are actually plugged and the ECM is trying to adjust but can't because the readings are just that far out of range eventually making the CEL come on, maybe also causing the surging. I would start with the cats and eliminate that CEL/issue before getting into what I mention below on the trans. Also if you have access to a scan tool or know someone that has one to check the throttle pedal across its sweep in case it has dead spots, this will cause surging as well. With the mileage you have the cats could very well be plugged depending on idle time over the life of the engine and driving styles etc.

At my work we experienced similar surging symptoms with some of our fords trucks (mainly f-550) but without CEL's, took a while to diagnose and narrow down the issue but it ended up being the solenoids in the trans of all things. When they were either cold or getting too hot the resistance in the coil in the solenoid would change enough that when the TCM/ECM would send the signal (PWM) to shift to the next gear the coil wouldn't actually energize properly to shift, so the ecm would compensate by derating/defueling a bit to soften the shift and would create/cause a surging. We've had this on two of our trucks now in the last couple months, we did similar parts changing and diag that you have, (coils, plugs, injectors, fuel pumps(when near low PSI spec), throttle bodies etc.) took us quite a while to figure it out but changing the shift solenoids out has corrected the problem. We never had any stored codes or CEL's either which made it difficult to troubleshoot. Pay close attention to how and when your jeep normally shifts when its not doing the surging to when it is, may be a similar issue.

Hope some of this helps.

 

hey buddy... I'm battling exact same issue... cat efficiency bank 2 code... loopy at idle randomly especially cold at idle but does it at slow speeds and warm... driving me nuts! I need help...

Please tell me you figured it out? 🙏

 

My 2014 JK has a similar issue, it has this minor surge/hesitation at around 2500 rpm when under load it also seems to have a power loss at very low speeds, it’s fine when I rev it in neutral. It has on two instances shuddered to a stop, something I am not able to replicate, I simply restarted and it ran fine. I changed the fuel pump thinking that it was maybe an issue there.

No codes.

I’ve asked three different mechanics, none of them gave the same answer, none of them seemed particularly concerned - The attitude is generally, no code no problem.

I recently changed the transmission oil (I regret not changing the shift solenoids while I was down there), oil was clean.


I have changed the crank position sensor as that was an easy item to troubleshoot, however that did not fix the problem.

The next thing I want to look into is the possibility of a catalytic converter(s) issue. If this doesn’t work then I am afraid things might start getting more expensive 😂. It’s also not as noticeable, but it’s definitely different to what it used to be.

So I eagerly am looking at thread, and I will post once I figure this out. Hopefully you also get your jeep sorted.