6 spd MT hanging onto revs?

[X99104]

My 19 JLUR has done this since day one. I've learned to let off the accelerator 1/2 sec before pressing clutch. Keeps it from happening as bad. It screws me up going from one manual to next but all of my vehicles have some annoying quirk I have to deal with. I consciously slow my shift in the jeep.

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[HeavyUser]

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 the correct answer, my 18' GTi and 16' Si had the same issue. If you google "rev hang" you will find all the information on it you could possibly want.

 

[Myron]

Well I'll be. I had never run across this. Here's what a Road & Track article I found has to say:

"As Road & Track contributor Jason Fenske explains in his latest YouTube video above, rev hang in most modern cars with stick shifts is a result of manufacturers attempting to reduce emissions generated by the engine during gear changes. Why? Well, even after you let off the gas, there's still some fuel remaining in the intake manifold from the injectors that can get sucked into the engine off-throttle. That extra fuel causes a rich air-fuel ratio, which is bad for emissions."

 

[HeavyUser]

DA POWA of GOOGLES!!

 

[opiop]

Yeah, it's just rev hang. I had a 2017 WRX with a manual transmission and people commonly used a tuner to get rid of the rev hang because it was that bad. Nothing to be worried about at all. It's a pain to get used to but once you do it's not so bad, especially since Wranglers aren't sports cars so you're not going to be slamming gears!

 

[m3reno]

Hmm, what extra fuel?

Well, even after you let off the gas, there's still some fuel remaining in the intake manifold from the injectors that can get sucked into the engine off-throttle. That extra fuel causes a rich air-fuel ratio, which is bad for emissions. ... This throttle delay is what causes rev hang

 

[AlgUSF]

I'm getting used to the rev hang on my Jeep. It annoyed me at the beginning however I'm starting to condition it out of my conscience. I have to still pay a ton more attention in reverse to the clutch vs. accelerator or I'll stall it. There is a lot of voodoo about Auto Stop and such and I've found myself stuck at a red-light in traffic a few times. I usually try to shut off the ESS stuff right away.

 

[cgagnon99]

I'm getting used to the rev hang on my Jeep. It annoyed me at the beginning however I'm starting to condition it out of my conscience. I have to still pay a ton more attention in reverse to the clutch vs. accelerator or I'll stall it. There is a lot of voodoo about Auto Stop and such and I've found myself stuck at a red-light in traffic a few times. I usually try to shut off the ESS stuff right away.

Do you have a 2021 with the new software? I've read all about the rev hang here (my WRX had it before I tuned it), but I don't notice it on my new JLU at all! I had to wait for the new software to take delivery so I wonder if that was addressed as well?

 

[OldGuyNewJeep]

When are you guys shifting? I only get rev hang if I shift at very night rpm- like 5500. When I shift at 3000-3500, which is my normal habit, no hang.

I have a 2dr Rubi. Lighter and different gearing than JLU Sport/Sahara, but I wouldn’t think it’d make a difference with rev hang.

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