2020 Jeep JLU 6 Speed MT Issues

Turchman

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Strange, not sure about the loss of power thing and drop in MPG. Would be worth checking for codes like @Truchman said.

If your RPMs are staying consistent but speed is dropping then there is a problem in the drivetrain somewhere. I would most likely attribute it to the clutch slipping since it has been a known issue now. If your RPMs are dropping with your speed then that would be a loss of power.
I agree that it is most likely a slipping clutch, although if it is slipping that badly you would think you would smell it.

The engine sound makes me wonder of it is an intermittent misfire or something similar. It should throw a code, but it may stay as a stored pending code if it stops.

Maybe the knock sensor is retarding the timing under high load?
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StevenTexasJLU
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Strange, not sure about the loss of power thing and drop in MPG. Would be worth checking for codes like @Truchman said.

If your RPMs are staying consistent but speed is dropping then there is a problem in the drivetrain somewhere. I would most likely attribute it to the clutch slipping since it has been a known issue now. If your RPMs are dropping with your speed then that would be a loss of power.
That makes sense, I was thinking clutch also from the beginning but when I took it in for the "clutch recall" nothing changed and they didn't mention anything to me about the clutch being damaged in any way. From what I read they were supposed to inspect it when taking care of that recall but they could have just rerouted the wiring harness, checked the box and moved on with out really inspecting it for damage. Idk I have lost faith in the dealers maintenance departments due to past issues so im a bit biased when it comes to trusting them with any of my vehicles.
 
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StevenTexasJLU
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I agree that it is most likely a slipping clutch, although if it is slipping that badly you would think you would smell it.

The engine sound makes me wonder of it is an intermittent misfire or something similar. It should throw a code, but it may stay as a stored pending code if it stops.

Maybe the knock sensor is retarding the timing under high load?
Agreed, I have not experienced smelling the clutch burn but then again I have had a few nose surgeries leaving my ability to smell not so great I think it may be miss firing because I get a power pulse from time to time where it jumps forward and starts accelerating quick and dies off again with changing the pressure put on the pedal. Idk I'm going to try and check codes this weekend which will hopefully lead me in the right direction.
 

Turchman

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Agreed, I have not experienced smelling the clutch burn but then again I have had a few nose surgeries leaving my ability to smell not so great I think it may be miss firing because I get a power pulse from time to time where it jumps forward and starts accelerating quick and dies off again with changing the pressure put on the pedal. Idk I'm going to try and check codes this weekend which will hopefully lead me in the right direction.
Let us know when if you get a code. Lots of smart people on this forum.
 

Turchman

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Right, I'm not sure what it could be at this point
Since I will be getting a MT Rubicon in the next few weeks, I have vested interest in this thread.
 

Jason Oliver

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It could be possible there is a very slight incline when this is happening.

I have had the same experience with my 6 speed manual many times. I figured it out by noticing that it was happening in the same place on a particular road. But, the clue was when I was going in the opposite direction I could maintain speed in 5th gear. The area looked very flat - in fact, it "appeared" I was going downhill where I could not maintain 5th, and uphill when I could.

The only logical explanation in my case is that appearances can be deceiving.

In addition to that, after about 30,000 miles in my Jeep through all kinds of roads and hills, it is obvious that the 3.6 has NO torque under 2,000 rpm. 6th gear is useful to save gas while going even slightly downhill as low as 40 mph. On flat land it is useful over 65 mph.

Roads in the Carolinas are rarely flat. Given that, I accept that 4th gear may be needed often to maintain 55 - 70 on the highway. I use 5th gear the least. If I am in 6th on the highway and start losing speed, I just go to 4th until I start accelerating past my previous speed and then go back to 6th.

I have stock 245/75R 17 Goodyear all terrains. I would expect that any tire larger would exacerbate the situation.

Your mileage may vary.
 
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Update

So I went to AutoZone and tried having them use their reader and there were no stored codes. IV been doing some reading on Throttle body/Throttle Position Sensor and I feel that could be the issue. I feel the symptoms I have been having match up pretty well and that issue apparently doesn't trigger a check engine light that often. Thoughts?
 

rid34fun

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My 2019 6spd 3.6 gets great fuel mileage in 5th at up to 70mph. If I go to 6th, it is really for 75mph and over or you are out of the power band and the 3.6 doesn't have the torque to move the heavy vehicle. The auto is much, much better on the highway. The computer does it all for the driver. Lots of shifting and slipping in the auto to maintain 70 on various roads. I love my manual, but hate it on the highway as the gearing is too tall for 6th gear. But, I get 24+ in 5th at 70. I have an Altitude with 32" tires. The good thing, is that the 6th gear will last a long time:) They had to have gears to make the jeep go comfortably at 85mph, so 6th it is.
 

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Did you say you have a 3.6? Have you had any ESS issues? If yes, there have been a few posts on JL forum and several on JT about rocker arm issues in certain 3.6 engines with those issues but it should throw a code if it is that.

The 6 speed in the JL now has been roundly panned for only being a 4 speed with two overdrive gears.
 
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