6 spd MT hanging onto revs?

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
Here's a weird one that I've never experienced in 40 years of driving manual transmissions. My Jeep is a 2020 JL Sport S with the 3.6L and 6 spd manual transmission. The Jeep has only 1500 miles on it and has driven perfectly normally up until now.

So you know how when you're driving a manual and you depress the clutch to shift gears and engine speed falls off, right? My observation with the Jeep has been that the engine would drop off almost 800-900 rpm before re-engaging, so I've trained myself not to shift before about 2500 rpm in this vehicle.

However, out of the blue comes a new behavior, and instead of engine speed dropping off during the shift, it stays steady or even sometimes goes up a couple hundred. What could this be? It's lasted a week and hasn't gone away or changed.

I'd love to hear if anyone else has experienced this and figured out the cause. Thanks!





Advertisement

 

Elm

Member
First Name
S
Joined
Jun 10, 2020
Messages
5
Reaction score
5
Location
Baltimore
Vehicle(s)
BMW
just guessing - since a new vehicle like your jeep has more safeguards. But its like a bad idle air controller that when vehicle is in neutral with no throttle it add fuel to idle smoothly. So it seem like a bad sensor or software situation.
 

Goosed

Well-Known Member
First Name
Dave
Joined
Feb 29, 2020
Messages
415
Reaction score
437
Location
Ohio
Vehicle(s)
2020 JLUR
Here's a weird one that I've never experienced in 40 years of driving manual transmissions. My Jeep is a 2020 JL Sport S with the 3.6L and 6 spd manual transmission. The Jeep has only 1500 miles on it and has driven perfectly normally up until now.

So you know how when you're driving a manual and you depress the clutch to shift gears and engine speed falls off, right? My observation with the Jeep has been that the engine would drop off almost 800-900 rpm before re-engaging, so I've trained myself not to shift before about 2500 rpm in this vehicle.

However, out of the blue comes a new behavior, and instead of engine speed dropping off during the shift, it stays steady or even sometimes goes up a couple hundred. What could this be? It's lasted a week and hasn't gone away or changed.

I'd love to hear if anyone else has experienced this and figured out the cause. Thanks!
This has been a “Jeep Thing” since the 2007 3.8l came around. Got worse with the 3.6 in 2012.

Livernois Tuning is trying to get a handle on if they can fix it. Or a couple guys switched out to a centerforce and it sounds like it fixes it.
 

EchoCharlie1

Well-Known Member
First Name
Frank
Joined
Aug 12, 2020
Messages
77
Reaction score
152
Location
Florida
Vehicle(s)
'21 JLUR; '17 F-250 FX4 Platinum; '15 Tesla S 85D; '15 Volvo XC60 T6; '16 Ducati Monster 1200R; '09 Vans RV-6
Occupation
Navy "Mustang" (ret); Engineering Manager, Space/Maritime Programs
I experienced this, as well, on our ‘18 JLR and presumed that Jeep had programmed the ECU for rev-matching to allow for smoother acceleration. However, I have been mistaken before (I think it was around 1987). :CWL:
 

zrickety

Well-Known Member
First Name
Ricky
Joined
Aug 7, 2020
Messages
298
Reaction score
357
Location
Americus GA 31709
Vehicle(s)
2020 Rubicon Sarge 6MT
Occupation
Technician
It looks like it has a dual mass flywheel (DMF). This causes rev hang from the extra inertia, they are quite heavy. Known issue on the Volkswagens.
My 2020 has done this since new.
 

JL Fan

Well-Known Member
First Name
JL Fan
Joined
Jun 14, 2019
Messages
85
Reaction score
99
Location
Fort Worth
Vehicle(s)
Jeep Wrangler JLU Sport S
’19 JLU Sport S 6M...with 15K. Never experienced this. Have you had the clutch recall done? Since yours is a ‘20, it may not apply. Just a guess?
 
OP
Myron

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
  • Thread starter
  • Thread Starter
  • #7
This has been a “Jeep Thing” since the 2007 3.8l came around. Got worse with the 3.6 in 2012.

Livernois Tuning is trying to get a handle on if they can fix it. Or a couple guys switched out to a centerforce and it sounds like it fixes it.
I experienced this, as well, on our ‘18 JLR and presumed that Jeep had programmed the ECU for rev-matching to allow for smoother acceleration. However, I have been mistaken before (I think it was around 1987). :CWL:
It looks like it has a dual mass flywheel (DMF). This causes rev hang from the extra inertia, they are quite heavy. Known issue on the Volkswagens.
My 2020 has done this since new.
This is great info guys. Even though it's clearly kind of a goofy thing, it's just good to know that it's common and not a problem. It doesn't really bother me, so I guess I just won't worry about it.

Thanks all for sharing your knowledge.
 
OP
Myron

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
  • Thread starter
  • Thread Starter
  • #8
’19 JLU Sport S 6M...with 15K. Never experienced this. Have you had the clutch recall done? Since yours is a ‘20, it may not apply. Just a guess?
Thank you, Ed. My Jeep was built in June and when I checked the VIN against the list of those with recalled clutches it did not appear to be affected.
 

ChattVol

Well-Known Member
Joined
Jun 29, 2018
Messages
2,444
Reaction score
2,538
Location
Tennessee
Vehicle(s)
JLU 4 door
Here's a weird one that I've never experienced in 40 years of driving manual transmissions. My Jeep is a 2020 JL Sport S with the 3.6L and 6 spd manual transmission. The Jeep has only 1500 miles on it and has driven perfectly normally up until now.

So you know how when you're driving a manual and you depress the clutch to shift gears and engine speed falls off, right? My observation with the Jeep has been that the engine would drop off almost 800-900 rpm before re-engaging, so I've trained myself not to shift before about 2500 rpm in this vehicle.

However, out of the blue comes a new behavior, and instead of engine speed dropping off during the shift, it stays steady or even sometimes goes up a couple hundred. What could this be? It's lasted a week and hasn't gone away or changed.

I'd love to hear if anyone else has experienced this and figured out the cause. Thanks!
Not sure...I do know you are lugging the 3.6 engine shifting at 2500rpm. The 3.6 isn't a torque monster and needs to rev...better to shift at 3000-3500 rpm in normal driving.
 
OP
Myron

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
  • Thread starter
  • Thread Starter
  • #10
Not sure...I do know you are lugging the 3.6 engine shifting at 2500rpm. The 3.6 isn't a torque monster and needs to rev...better to shift at 3000-3500 rpm in normal driving.
Yes, it's been a learning experience for sure.
 

LLANERO

Well-Known Member
First Name
Dario
Joined
Apr 24, 2018
Messages
451
Reaction score
519
Location
Virginia Beach
Vehicle(s)
2018 JL
First time I experienced this issue was with my 05 Xterra.
I think it is due to the drive-by-wire factory programing.
It affects auto trannies as well as you can no longet control your speed with the throttle when rock crawling.
Superchips claims their tuner fixes it, but don't know anybody who has it that can confirm of this is true.
 
OP
Myron

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
  • Thread starter
  • Thread Starter
  • #12
Like EchoCharlie1 above, when I first noticed it I thought for sure my 19-yr old had dug into the menus and found a rev-matching option and enabled it. I texted him (using CarPlay) and asked, but nope, no such thing. But that's exactly what it feels like.

I dunno. He got back from a weekend trip in it tonight and I took it around the block and it seemed almost normal.
 

m3reno

Well-Known Member
First Name
Sal
Joined
Jul 21, 2018
Messages
404
Reaction score
259
Location
caldwell
Vehicle(s)
2018 Jeep Wrangler JL
It's Called rev hang and car companies have been doing this for the past ten years or longer! The reason is in between shifts by keeping the revs high it burns off the extra fuel therefore lowering emissions.. I can't seem to enjoy my manual until this is resolved
 
OP
Myron

Myron

Well-Known Member
First Name
Myron
Joined
May 21, 2020
Messages
99
Reaction score
100
Location
Mitten State
Vehicle(s)
2020 Wrangler, 1964 Land Rover SIIA 88
  • Thread starter
  • Thread Starter
  • #14
It's Called rev hang and car companies have been doing this for the past ten years or longer! The reason is in between shifts by keeping the revs high it burns off the extra fuel therefore lowering emissions.. I can't seem to enjoy my manual until this is resolved
Hmm, what extra fuel?
 

Goosed

Well-Known Member
First Name
Dave
Joined
Feb 29, 2020
Messages
415
Reaction score
437
Location
Ohio
Vehicle(s)
2020 JLUR
It's Called rev hang and car companies have been doing this for the past ten years or longer! The reason is in between shifts by keeping the revs high it burns off the extra fuel therefore lowering emissions.. I can't seem to enjoy my manual until this is resolved
This is exactly why we deal with it. If you try and tune it out and go aggressive you’re asking for issues down the road.
 

Advertisement




WheelsASAP
 



Advertisement
Top