Auto Tranny Holds Gears Way Too Long

[Orcasupreme]

If you don't think it's right, I'd take it in to the dealer and at least get it documented.

That’s a very good point. Thanks.

— Dave

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[MattKay]

You can take it to the dealer and ask them to put it back in learn mode.

does that really work? What’s it do in learn mode that’s any different than just shifting when it wants to right now?

 

[ShadowsPapa]

does that really work? What’s it do in learn mode that’s any different than just shifting when it wants to right now?

These learn and adapt. I noticed with my 2020 after a PCM update/flash it shifted very differently and relearned after a while.
It's not a matter of "when it wants to" it's a matter of learning the driver and other criteria and matching things up. It's not at all like a legacy transmission where governor pressure is balanced against throttle pressure and that's all there is to it.

 

[BearFootSam]

does that really work? What’s it do in learn mode that’s any different than just shifting when it wants to right now?

The engine and transmission control modules are tightly integrated in these trucks. One or the other will learn your driving style and adapt over time to respond to what the operator's apparent intentions are. If you are always gentle on the throttle and keep an easy pace, I'm convinced the truck will adopt a more efficient gear change schedule for the conditions. In my two years with the JTR I've observed it is has always upshifted aggressively. For instance, going up a minor grade on my road at 45mph the truck is in 7th and might jump to 8th, instant economy in the high 20's.

From our town at sea level, it's a 15 mile drive up the mountain to 5,400'. On the grade up the truck will try to hang around 2800 rpm, occasionally jumping up to the low 3,000's when it drops a gear or two on slower tight turns.

To get it up to 5,000 rpm I have to really lean on it and then it drops two gears and runs.

Out of my driveway we are on a 55mph road with a stop free 20 mile trip to town, so after initial acceleration we are just cruising. Then about 30-40% of our driving time each week is on rough forest roads to our berry and mushroom picking spots. Those roads are tight and steep climbing up and down a thousands of feet. On those runs the truck operates between 3,500-4,000 while plowing the deep gravel upslope. So following my theory, because our driving involves little stop and go, and rare occasions for jack rabbit starts, the truck has assumed a more economy focused attitude.

I found this information on shift dynamics on a site discussing the Zf 8 speed operation in the BMW world. There are apparently tuners who have identified this driver behavior ratings influence over performance.

 

[JTGuy]

My modified 22JTR has 37s and 4.88s. It shifts just fine most of the time but sometimes will hold a gear under light throttle up to 4000+. So I just do a manual upshift to get it under 3K and then let it do its thing. It will cruse nicely at 75+ in 8th, much better than the 4.10s did.

 

[WILDHOBO]

My modified 22JTR has 37s and 4.88s. It shifts just fine most of the time but sometimes will hold a gear under light throttle up to 4000+. So I just do a manual upshift to get it under 3K and then let it do its thing. It will cruse nicely at 75+ in 8th, much better than the 4.10s did.

My lifted 21JTR on 37’s acts very similarly. I have 5.13:1 gears. I can get 8th gear above 80 on the flats. But there are very few flats where I am.

 

[GI Grandpa]

You can take it to the dealer and ask them to put it back in learn mode.

I didn't know there was such a thing. My 21 Mojave does the same thing, usually while merging onto the interstate, uphill or down, it will hold 5,000 rpm even after I have taken my foot off the accelerator and I have to tap and sometimes stand on the brakes to get ot to upshift. I took it to my dealer, who I do trust and they weren't able to replicate the problem or find any thing wrong. Now I guess I have just learned that it happens and I anticipate it

 

[Zachanadandy]

The 3.6L doesn't make 150hp to the wheels until 4k rpms, of course it holds shifts when climbing hills. It doesn't make any power at low rpms.

 

[WILDHOBO]

The 3.6L doesn't make 150hp to the wheels until 4k rpms, of course it holds shifts when climbing hills. It doesn't make any power at low rpms.

Every time I drive mine it sees 5k rpms. I only let off and feather the throttle to induce a shift when it gets close to 6k. I’ve been driving it that way for 60,000 miles. No issues as of yet.

 

[Orcasupreme]

I could probably deal with it a little more easily if my Durango, with the same engine/tranny, didn’t handle the same roads with grace and a reasonable transmission shift pattern. I know the rear end gearing is different, but good Lord.

I always heard people talk about how great the 8spd+Pentastar combo was in the JL/JT, but I’m not feeling it. This trans feels like it has a bunch of drunken monkeys randomly pulling levers inside of it.

 

[Minty JL]

Yeah mine likes to hold/hang gears even if I let off the pedal 100%

A few months back I did a complete relearn with the Autel.....meh, guess this is the way it is

 

[JTGuy]

Sure, let's make an engine that makes HP at high RPM and then give it cam and lifter problems.

 

[Stan H]

Mine will hold a gear going up a hill . If I let up a little it will shift up if it was enough torque. It is in the computer programming . Mine as it aged started shifting wonky in 234 . I now let it run for at least 10 min. In the morning and shift manually 1-4 after I do that the first time it shifts correctly the rest of the day. It's weird. I have adjusted the tire size and have changed the transmission oil. So I chalk it up to age . Mine has 99,563 miles it locks up solid in every gear still. When it is cold in the morning it tries to shift too fast . So I shift into 2nd at 2k and 3rd and 4th at 3k and then back k into drive and it does fine the rest of the day.. whats your theory on that ?

 

[Stan H]

 

[ZeeJay]

I took mine in last year for this. Hang time in any given gear was ridiculous. Manually take into next gear and I’d find it would pull just fine, sometimes two gears and even on incline would pull just fine. Of course dealer was unable to duplicate and cock their head like a curious dog.
What I believe is the load profile is super sensitive and value of throttle input and how its rationalized in calibration keeps it hanging, I also believe the hysteresis in throttle value input values are too long which is why it seems to take a complete release of throttle and a significant wait time for it to capture next gear. The only correction would a different calibration, which is beyond us or any dealer.

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