3.6L "Hiccup"

[zrickety]

I tried searching and found nothing. Can you share a link to some of the similar cases?

EDIT: I tried searching through the TSBs and this was the closest thing I could find:
http://www.wkjeeps.com/TSB/tsb_wk_1800409a.pdf

It sounds very similar but its for a 2009.

If the problem is software then there is no chance of us getting it fixed. Dealerships play dumb and give you the runaround until they get some instruction from the manufacturer.

Sorry, did not mean a TSB. I've seen numerous posts on this forum, everyone notices about 2500 rpm, 3rd gear if I recall.

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[Bocephus]

2018, 3.6, and manual transmission JLUR. I had the hiccup...kind of a hesitation as folks are describing. Fwiw, it’s gone since I supercharged with the magnuson blower and tune.

This concern / issue might be worth raising in the Livernois calibration / tune thread. See if that tune (which sounds awesome) has eliminated the issue.

 

[Coolbaldguy]

I have a 2019 3.6 automatic. One day while driving around town, I noticed a “random hiccup “ . When I returned home I disconnected the battery for 5 minutes. Reconnected the battery and the problem has never reoccurred.

 

[neil]

2020 nearly stock, I notice the same thing, it's right below 3K for me. I think engine or TC. oil pump also kicks in around there.

I am going to reply to myself and add some info on the hiccup.

My manual jeep does this, my wife's auto, no, and I've looked there for it.

This is not slipping as I have felt it in other manuals.

I generally put 91 only in our jeeps, why, because it's in a big tank I use at a barn I own and already paid for....it is also ethanol free. When I need gas and need a fill up, I generally use Top Tier 93-89 depending on where I am and what they are selling.

I did try to re-create w traction control off a couple times out of curiosity......could not get it to replicate w traction control off.

Does it bug me? No
Do I think it's going to break? No
But still curious.

 

[ForeOSU]

My 2020 3.6L auto has the same hiccup. If i'm stronger on the gas pedal, it does not seem to do it. But if I'm just trying to go easy (like in my neighborhood when going ~25 mph is where I noticed it the most), then I notice it more often.

My idle is rough like that, too. I came from a built G8 GT and that push-rod V8 had a rough idle, so its not that strong. But definitely noticeable when cold.

 

[Truckn]

Lots of good suggestions here. I agree that it needs to be looked at. For reference, I've also got the 6 speed. I've not felt any hesitation like that and the idle is so smooth, that with music on to where I can't hear the engine, I've gotten out of the Jeep thinking that it was off. So the idle should be very smooth. (Of course, old age hs a ittle to do with forgetting the engine is off. I'm also still not used to not having a key, and never will be, since I still have my JK.)

Remember, too, that noise and vibration can be VERY subjective. Some are more sensitive to certain frequencies or subtleties of it than others.

Has it always done it or did it develop after you put a few hundred miles on it?

Side note: I do know that @Elsinore73 gives a great example. I feel absolutely no difference between 87 and 93. But my friend who helped design the Pentastar said that the test equipment shows with absolute certainty that there is a difference in smoothness in the Pentastar between lower and higher octane. The test equipment showed it clearly in development. But most can't feel it. He did offer a quite detailed and interesting engineering explanation as to why. I don't understand it enough to be able to explain it, but it made perfect sense. So my friend runs 93 in his Chrysler 300. I don't. I don't feel the benefit at all. But you might try it just to see what happens.

If someone with a 6 speed who doesn't feel these things lives close to you, meet up and have them drive yours and you drive theirs. That'll confirm it and help you to explain to the dealer or tech what is going on.

But it does not sound normal, to me.

Another thing I'd suggest, if you don't do it already, is to run Top Tier gas. That means a big brand, like Shell, Exon, Mobil, Chevron, Phillips 66, and others. You can google it and find the list. But i think that's important, too.

One other thing my engineer friend said. Run this engine hard. Give it an Italian tune-up once in awhile. It is good for it. It might even help smooth things out. Get it to the upper rpm range when you can. It cleans things up, gets fresh oil to certain areas in the complex valve train, and its fun with that 6 speed! It is fine if you don't and will last a long time, but it is better if you do. Again, that's straight from one of the Pentastar's parents!

Let us know how it turns out!

All good suggestions. I do run Shell 91 octane. Unfortunately we don't get 93 here in California.
I didn't intend to always run 91, but I figured it might help while breaking in the engine since there is a greater chance of pre-detonation in a brand new engine. I have about 1,500 miles now, I think I may try putting 87 in to see if things get worse.

That's cool that you know someone that helped design the engine, great to get advice direct from the creators!

I saw OP's update after I posted. I'd suggest riding in an older 2018 or 2019. Maybe sometimes the most recent firmware in the PCM isn't as good as an older version?
Who knows, but It is interesting that the TC may be involved. Can the TC be 100% disabled? Maybe a Tazer can do that?

Maybe just reflashing or replacing the PCM might make a difference, even if the current one shows no issues. If I were the dealer service tech, Id consider that.

Also a great suggestion. I actually installed the Tazer last week and am running TC FULL-OFF. Given that the issue happens rarely for me with TC semi-off, I have to give it some time to see if this FULL OFF really works.

Earlier it was suggested that it may also be variable valve timing, which I think is also a very strong possibility -- or software like you also suggested.

What I do know is that turning TC off (without Tazer) showed a great improvement but did not eliminate it. So I suspect it is a software mechanism that is tied to TC. By turning TC off it eliminates one variable but does not fix it. This is a total guess but makes sense to me since modern engines relate all the signals together to make decisions.

 

[Truckn]

2018, 3.6, and manual transmission JLUR. I had the hiccup...kind of a hesitation as folks are describing. Fwiw, it’s gone since I supercharged with the magnuson blower and tune.

This concern / issue might be worth raising in the Livernois calibration / tune thread. See if that tune (which sounds awesome) has eliminated the issue.

I vote the factory upgrades us all with a supercharger and a tune haha
J/K, but I bet the tune fixed it. This supports the theory of it being software related.
I plugged in a Tazer, so my warranty is already potentially at risk... why not get a tune!

I have a 2019 3.6 automatic. One day while driving around town, I noticed a “random hiccup “ . When I returned home I disconnected the battery for 5 minutes. Reconnected the battery and the problem has never reoccurred.

I will try this. Could be something bad learned from cruddy gas or some 18 year old kid driving it at the dealership.

I am going to reply to myself and add some info on the hiccup.

My manual jeep does this, my wife's auto, no, and I've looked there for it.

This is not slipping as I have felt it in other manuals.

I generally put 91 only in our jeeps, why, because it's in a big tank I use at a barn I own and already paid for....it is also ethanol free. When I need gas and need a fill up, I generally use Top Tier 93-89 depending on where I am and what they are selling.

I did try to re-create w traction control off a couple times out of curiosity......could not get it to replicate w traction control off.

Does it bug me? No
Do I think it's going to break? No
But still curious.

I totally agree, it's not a clutch slip.
I'm in the same boat -- I don't think its going to break. It no longer bugs me now that I know it's not just mine... But I'm still curious.

My 2020 3.6L auto has the same hiccup. If i'm stronger on the gas pedal, it does not seem to do it. But if I'm just trying to go easy (like in my neighborhood when going ~25 mph is where I noticed it the most), then I notice it more often.

My idle is rough like that, too. I came from a built G8 GT and that push-rod V8 had a rough idle, so its not that strong. But definitely noticeable when cold.

Does it go way when it warms up?

 

[Truckn]

I'm curious... what is the idle RPM for those of you that feel the rough idle, and those of you that do not?

I have a rough idle and my idle RPM is about 600 to 650. If I raise the RPM to 750 with the gas pedal the rough idle becomes silky smooth.

 

[neil]

I really don't have a rough idle. Mine seems to be better w the pennzoil vs what the factory fill was.

Is this at start, or all the time?....if my idle on a warm engine was wonky I would look at whole host of things.

 

[JeepCares]

Hey, OP- please get back to us on your little experiment; I’m really looking forward to what you find out.

I have the 6 speed too and just noticed this. I have about 25,000 miles on mine and never experienced this until the last couple hundred miles. The only thing I’ve done recently to strain the jeep was rescue a Rogue out of a ditch when it snowed a few weeks ago, which made me think maybe I put too much stress on the clutch... but your traction control theory is interesting too because it has been raining a lot lately here. I’ll pay more attention tomorrow.

I’m not feeling the “hiccup” but definitely feel a rough idle. ‘21 JLUR 6-speed, 2500 miles. Oh yeah, I don’t feel much accelerated in 3rd...almost flat.

Is this concern still present for the both of you? If so, we suggest visiting the dealer but if you need further assistance or would like to discuss, send a private message.

Kate
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[jaozus]

My ‘19 JLUS 6speed w/ 3.6 V6 had the “hiccup” as well. I created a post here a while ago and described it as a “pulse”. Happened in 3rd gear, accelerating. Usually between 47-53mph. Happened for a while and then it just stopped. No idea what happened. I did have the initial recall for the clutch done so maybe that was it?

 

[ChromeToaster]

sorry to resurrect this but I've got a 21 6 speed Rubicon 2 door with the same stutter under accel in 3rd gear happens every time under light accel between 43 and 44mph only in 3rd gear. Easy to replicate by setting cruise at 43 and then bumping it up to 44 on the steering controls. sometimes its enough that when the power resumes it will lurch the whole jeep nothing insane but enough to worry me. I'm scheduling dealer visit right now. mine has done it since new and but sitting at 11k now but I did install an aftermarket exhaust which makes the engine note change more noticeable so its annoying now... I'll post if anything is found I'm sure they will do a tune since the MT recall for software is out now so maybe that will fix it even.

 

[DanW]

sorry to resurrect this but I've got a 21 6 speed Rubicon 2 door with the same stutter under accel in 3rd gear happens every time under light accel between 43 and 44mph only in 3rd gear. Easy to replicate by setting cruise at 43 and then bumping it up to 44 on the steering controls. sometimes its enough that when the power resumes it will lurch the whole jeep nothing insane but enough to worry me. I'm scheduling dealer visit right now. mine has done it since new and but sitting at 11k now but I did install an aftermarket exhaust which makes the engine note change more noticeable so its annoying now... I'll post if anything is found I'm sure they will do a tune since the MT recall for software is out now so maybe that will fix it even.

Has yours had the recall re-program yet? I'm wondering if that might have code in it that would help with issues like this?

 

[ChromeToaster]

Has yours had the recall re-program yet? I'm wondering if that might have code in it that would help with issues like this?

No mine is the stock tune still. (built oct 2020) I'm scheduled for the 20th and assuming they will do the recall update that day too.

 

[DanW]

No mine is the stock tune still. (built oct 2020) I'm scheduled for the 20th and assuming they will do the recall update that day too.

Ok, keep us posted. I don't know where I read it but I saw somewhere that the update brings the engine ECM to the latest firmware, as well as the recall program. If that's true, then maybe there is a chance it will address that for you.

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