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2021 JL Throttle Surge (manual trans)

CarterMT

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Hi everyone,

Long-time visitor to the forums, first time poster. Special ordered a 2021 2 door JL Rubicon with the six speed manual earlier this year. Have had it about two months, and I'm disappointed to say that mine experiences the throttle surge that I have since learned has been documented here (and elsewhere). While coasting to a stop or between shifts, the RPMs jump somewhere between 1500 and 2500, sometimes dropping back to idle, and sometimes holding the higher rev until coming to a complete stop. You hear the engine, obviously, but also feel the vibration in the clutch pedal. It does this almost every time. It is particularly annoying, because there is variability in the surging behavior (in other words, you can't get used to it).

I've read other owners on the forums who have chronicled their own experiences with this, but I have yet to hear of a fix. Took mine in to the dealer last week, and drove it with the service manager, who told me that there almost certainly is not a solution to this problem. This was later confirmed by the technician, who also drove drove it.

I'm here today to ask for feedback from others who have experienced this. Is anyone aware of anything that can be done to resolve this problem? I've driven lots of vehicles (I'm a manual transmission guy), and I cannot imagine how such a problem could be allowed by Jeep to persist, especially since we are now four years deep into the JL's life cycle. Involuntary revving while coasting or shifting cannot be considered normal by anyone's standards, IMO. I otherwise love my new Jeep, and I'm prepared to do whatever I can to get this fixed.
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supermike

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rev hang?
how about post a video?
 
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CarterMT

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rev hang?
how about post a video?
It's worse than rev hang. This is a youtube video posted by someone else which gives you some idea:

 

supermike

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I would say its all the same, they all do that. dont know why but as long as the vehicle is moving above 5 mph, clutch in the rpm drop to 800 and then stays around 1500 rpm.. just don't let it drop all the way down. oh BTW the rev hang is HORRIBLE on the JL....



 

supermike

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And mine also idle horribly, since day one. I can feel the whole seat shaking, but sometimes it's buttery smooth like engine is off...5 qt oil, not over filled, pushed all fuse in, not related to fuel....dealer is useless...not happy but what can i do.
 

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I’ve had a little but doesn’t seem to be an issue.
 

Bigfx1

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Have you gone to the dealer for the update yet? I don’t see the gear indicator on your info panel in the gauge cluster. I have never had this issue
 

supermike

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Have you gone to the dealer for the update yet? I don’t see the gear indicator on your info panel in the gauge cluster. I have never had this issue
manual don’t have PRND.
 

liquids

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Why take it out of gear? IIR, the engine computer will cut off the fuel injectors after a few seconds when in gear with no throttle. No gas usage then. Put in the clutch and it needs gas to keep the engine turning.
 

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manual don’t have PRND.
They do now with the latest firmware update it shows what gear you're in on the dash under the speed. Also the surge is in fact still there after that update, I believe its just normal part of the map. I agree its dumb though the revs hang way too long almost all the time.
 

supermike

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They do now with the latest firmware update it shows what gear you're in on the dash under the speed. Also the surge is in fact still there after that update, I believe its just normal part of the map. I agree its dumb though the revs hang way too long almost all the time.

Live and learn...Mine was updated 1 year ago for rough idle, but no result, doubt another updated will fix things, but they don't seems to bother me.
 

R00STER

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Maybe Livernois or one of the other tuners can fix this when they get some time on a manual with the 3.6. Until then I guess we are stuck with it.

I haven't taken delivery of my manual JLUR yet, so I am deliriously hopeful that they have updated everything by now.....but after reading this and other posts on this tranny, it is not likely.

Question for those who experience the hang, does it impede engine braking when down shifting?
 

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More than likely...you can thank the EPA for your rev hang woes. Many manufacturers program a bit of rev hang to help with emissions...it’s kind of like the auto stop...it doesn’t save much each time it does it, but once you’ve added up all of the times it does it and all of the vehicles on the road...supposedly it makes a difference...
 

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Yeah this is intentional. One of the software updates I got a long time ago seemed to reduce the frequency and severity of this phenomenon but didn’t eliminate it entirely (would have been before the 2021’s started being built so yours already has it). It’s one of those things they do to make emissions cleaner (I don’t think it’s for better MPG’s, just cleaner tailpipe emissions).

Regarding the gear showing below the vehicle speed- is that only on the screen that shows MPH/KPH? I assume it doesn’t apply to the other screens like the MPG screen, the vehicle info screen, the trip odometer screen, etc.

Can someone with manual transmission please post a pic of this?

My jeep was just at a dealer 3 weeks ago and I said to update everything. Do all the software updates. They said they did but I’m not seeing a gear indicator (as if anyone needs that... who drives stick and needs to look at the dash to see what gear they’re in?)
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