Auto Tranny question (based on a pet peeve)

jorgelrod

jorgelrod

Hooked
From my house to work there is this hill, I would say a 6-8 degree incline for about may be 1200 feet, at the bottom there's a light. when I was on my 3.73 factory gears and the 33" tires I have I would see it shift from 1st to 2nd gear at about 2500-3000 RPMs and from 2nd to 3rd it would go all the way to 5K before switching to 3rd gear starting from the light, even under medium gas pedal push, not flooring it. I used to think that it was due to the tire size and the gears. A year later and the switch to 4.56 and it still does that. If I am going up the hill and let of the gas for a split second or force the gear shift on the stick to 3rd I can see that it can still run up and increasing velocity at a nice 2500-3000 RPM, is there a reason why it wouldn't want to change to 3rd and run on lower RPMs and keep climbing at 4K RPMs if I keep the gas pedal steady??

As I said if I punch it, it will eventually shift at 5K, if I let off the gas for a second it will shift to third. I stay constant it will go all the way to the top of the hill at 3500-4000 RPM until I hit the crest.

I'm just curious, why it does that
 
Angry Aussie

Angry Aussie

New member
jorgelrod said:
From my house to work there is this hill, I would say a 6-8 degree incline for about may be 1200 feet, at the bottom there's a light. when I was on my 3.73 factory gears and the 33" tires I have I would see it shift from 1st to 2nd gear at about 2500-3000 RPMs and from 2nd to 3rd it would go all the way to 5K before switching to 3rd gear starting from the light, even under medium gas pedal push, not flooring it. I used to think that it was due to the tire size and the gears. A year later and the switch to 4.56 and it still does that. If I am going up the hill and let of the gas for a split second or force the gear shift on the stick to 3rd I can see that it can still run up and increasing velocity at a nice 2500-3000 RPM, is there a reason why it wouldn't want to change to 3rd and run on lower RPMs and keep climbing at 4K RPMs if I keep the gas pedal steady??

As I said if I punch it, it will eventually shift at 5K, if I let off the gas for a second it will shift to third. I stay constant it will go all the way to the top of the hill at 3500-4000 RPM until I hit the crest.

I'm just curious, why it does that
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My jeep has always hated long hills even when it was stock it didn't or couldn't handle long climbs. I have 3.6 and still hates hills. Now that I'm on 5:13 and 37s it still hates long hill climbs. Sadly there's not much you can do unless you put a more powerful motor under your hood.
 
hinrichs

hinrichs

Caught the Bug
I have been wondering this as well, it just seems to hold onto certain gears way longer than I think it needs to. I am also on 5.13s and 37s. Sadly I only really drove it for about 2 weeks stock so I cant even remember what it was like lol.
 
WJCO

WJCO

Meme King
It's most likely normal. Mine does it too, but way more sluggish with my stock gears. I'll retest drive next week in the mountains after gears are in. One of the things that the trans shifting is controlled by is throttle pressure (nowadays electronically with the TPS sensor), so being able to over-ride it with the throttle is just that to force it to shift. Based on the speed or increase of speed that the Jeep is going up the hill, the trans may not shift based on the load present because it senses that more rpm is needed to finish the climb. Sometimes on a long grade, mine will shift when it's too early and then it's really sluggish with the larger tires and stock gears, I wish it would stay in a lower gear longer.
 
Journeyman

Journeyman

New member
Uhhh. I hate this. Mine does the same thing on only certain hills by my house. Literally holding onto 5k rpm with almost know throttle and still refusing to shift.
There's actually one spot where mine shutters and surges for about 100' 3rd gear just at the start of the hill. I have never experienced this anywhere else.
35" with 411's
 
AllAmericanInfidel

AllAmericanInfidel

Caught the Bug
Mine does this only when I first start driving it. The first couple of times through the gears it will hold second into third. Once I get going and everything warms up it does not do it anymore. Never really thought much of it though. Does it whether I'm on a hill or flat ground though. Interesting.
 
cozdude

cozdude

Guy with a Red 2-Door
I have noticed it on hill climbs but honestly I would have it any other way. I would rather have the rpms a little higher for the climbs so it doesn't bother me
 
Angry Aussie

Angry Aussie

New member
One thing that helps for me is taking as much of a run up before hitting the hill. I'll speed up as much as I can before I get to the hill. It helps carrying as much speed as possible before reaching the hill. There will be spots where this isn't possible but may be worth trying.
 
Journeyman

Journeyman

New member
Mines different then. It's holding and not shifting when there's plenty of power on tap. Usually it seams to do it when I basically started from an almost dead stop at the bottom of the hill and accelerating up the hill going through the gears.
 
jeeeep

jeeeep

Hooked
That's the nature of the automatic, it's not so smart on the hills when it comes to choosing the proper gear so use your tap shift and shift to the gear you want.

On my 2010 I lock out OD. On the 2015 I use the tap shift, similar to locking out OD but with more options :thumb:
 
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WJCO

WJCO

Meme King
jeeeep said:
That's the nature of the automatic, it's not so smart on the hills when it comes to choosing the proper gear so use your tap shit and shift to the gear you want.

On my 2010 I lock out OD. On the 2015 I use the tap shift, similar to locking out OD but with more options :thumb:
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I don't use OD on hills either, it definitely helps. And I think you meant 'tap shift?' :idontknow:
 
jeeeep

jeeeep

Hooked
WJCO said:
I don't use OD on hills either, it definitely helps. And I think you meant 'tap shift?' :idontknow:
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hahaha, i did mean tap shift, all the other times my phone dictation will not actually spell it out and this time it just drops it :cheesy:
 
Coop

Coop

Caught the Bug
Wonder if Jeep has a reflash for the tranny where you can pick the characteristics you want? They reflashed my Grand Cherokee for the better.
 
jorgelrod

jorgelrod

Hooked
Coop said:
Wonder if Jeep has a reflash for the tranny where you can pick the characteristics you want? They reflashed my Grand Cherokee for the better.
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Mine had the PCU and TCU flashed about 2 months ago but it still does the same so I think it's just the way Jeep engineers wanted it
 
R

rockcrawler73

New member
I hate it as well. I'm running an '08 with 5.13's and 37's. I also have a SC Traildash where I run the 93 octane tune. The power is there, but it sucks going up a hill. I never have it in OD unless I'm on the highway. Even then, going up slight inclines it will start to slow done. I also hate the fact that the Traildash will lockout 3rd and 4th gear. I have to get into the skinny pedal hard just for it to unlock :mad: . Anyone else with the Traildash have that issue and maybe a solution :crazyeyes: ?
 
jeeeep

jeeeep

Hooked
rockcrawler73 said:
I hate it as well. I'm running an '08 with 5.13's and 37's. I also have a SC Traildash where I run the 93 octane tune. The power is there, but it sucks going up a hill. I never have it in OD unless I'm on the highway. Even then, going up slight inclines it will start to slow done. I also hate the fact that the Traildash will lockout 3rd and 4th gear. I have to get into the skinny pedal hard just for it to unlock :mad: . Anyone else with the Traildash have that issue and maybe a solution :crazyeyes: ?
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Does the SC Traildash have the 'tow' tune option? if it does, try it. I have my SC using the tow tune, used to use the performance tune but found the tow tune offered better shift points especially with 37's.

FYI - if you adjust the tune and you find your transmission shifting like it's slipping or shifting too hard, return the tune to stock, disconnect the battery for at least 15 minutes, connect everything and put the tune back in. This happened to me as I was testing the different tunes and it almost cost me a bunch of money. Luckily the shop I took it to didn't try to take advantage, they told me it wasn't the transmission and suspected the PCU - this is what tipped me off to reset everything and it's been running fine since.
 
R

rockcrawler73

New member
jeeeep said:
Does the SC Traildash have the 'tow' tune option? if it does, try it. I have my SC using the tow tune, used to use the performance tune but found the tow tune offered better shift points especially with 37's.

FYI - if you adjust the tune and you find your transmission shifting like it's slipping or shifting too hard, return the tune to stock, disconnect the battery for at least 15 minutes, connect everything and put the tune back in. This happened to me as I was testing the different tunes and it almost cost me a bunch of money. Luckily the shop I took it to didn't try to take advantage, they told me it wasn't the transmission and suspected the PCU - this is what tipped me off to reset everything and it's been running fine since.
Click to expand...

Tried running the Tow Tune yesterday after reading this thread and it was still doing, except with less power. I have to try the reset and disco of the battery after I get home here in a bit. Thanks for the reply :thumb:
 
DemCoconuts

DemCoconuts

New member
For all that are wondering - it's a modern auto transmission, therefore computer controlled. How it shifts (at what RPM's and the likes) is based on a shift table (an information table) that the programmers at the factory decided on (which is why it shifts the same even when you regear/etc).

The shift points can be modified through certain tuners, or custom tunes. What the factory values are/what you could change to I have no idea, as I haven't moved into the world of tuning on my Jeep yet. Shift points is something I would like to play with when I do. That's just my basic understanding of it.
 
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