Something I notice when on hills... - 2014+ Jeep Cherokee Forums
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post #1 of 9 (permalink) Old 01-15-2017, 09:20 PM Thread Starter
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Something I notice when on hills...

Now, I'm not sure if this is a standard feature in auto transmissions these days, but in my previous experience with cars with autos, they don't seem to do this, and yet the Jeep does appear to.

When I am on a hill, it appears the car senses this (via some sensor that measures your angle, I guess?), and will hold the gear it's in as you approach a hill even if you don't keep your foot pressed moderately on the accelerator. And then when you hit the top of the hill, or the angle changes, then it will upshift then.

I just thought it was interesting that the transmission does this. Anyone else notice this?

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post #2 of 9 (permalink) Old 01-16-2017, 03:17 AM
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yes i have .jeep replaced 2 cars. a 2014 and a2015.i live on a hill and transmission will shift only after 5000 rpm.i tested 6 new cars,and all have the same problem.from gear 2 to 3 .my 2016 has the same problem.i gave up.i do like the car. no other problems.
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post #3 of 9 (permalink) Old 01-16-2017, 07:51 AM
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Coincidentally I was just thinking this about my 2017 KL the other day. I wanted to upshift during the incline to save fuel but it would not do it, but as soon as I hit the top and we levelled out it shifted right away. This was going from 7th into 8th gear at around 90 kph.

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post #4 of 9 (permalink) Old 01-16-2017, 07:52 AM
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Quote:
Originally Posted by Shoulder View Post
Now, I'm not sure if this is a standard feature in auto transmissions these days, but in my previous experience with cars with autos, they don't seem to do this, and yet the Jeep does appear to.

When I am on a hill, it appears the car senses this (via some sensor that measures your angle, I guess?), and will hold the gear it's in as you approach a hill even if you don't keep your foot pressed moderately on the accelerator. And then when you hit the top of the hill, or the angle changes, then it will upshift then.

I just thought it was interesting that the transmission does this. Anyone else notice this?
I believe this is the hill/grade assist function. You will find it under settings. You can turn it off or back on there. That is unless something has changed since 2014 model.
I turned mine off, early on, with my 2014 Limited. Three years later its still off. My opinion, no need to stress the transmission any more than needed.
I believe it will also help starting up from a stop on a steep hill to help with the roll back. That would be especially useful when towing.
My last 3 Jeeps did not have this function and I have learned to compensate without it.
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post #5 of 9 (permalink) Old 01-16-2017, 09:31 AM Thread Starter
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Originally Posted by Jeepster1 View Post
I believe this is the hill/grade assist function. You will find it under settings. You can turn it off or back on there. That is unless something has changed since 2014 model.
I turned mine off, early on, with my 2014 Limited. Three years later its still off. My opinion, no need to stress the transmission any more than needed.
I believe it will also help starting up from a stop on a steep hill to help with the roll back. That would be especially useful when towing.
My last 3 Jeeps did not have this function and I have learned to compensate without it.
I actually have no issue with it since I am so used to doing the same thing when I drove a manual as my DD. Keep on the lower gears to keep the revs and power up so I am not lugging the engine on the way up. I quite like the feature to be honest, and I'm not worried about stressing the engine frankly. Whether I am going off-roading, towing/hauling, flooring it on the on-ramp, or driving through city traffic 90% of the time, you're going to put some level of stress on the transmission, but I am confident it can handle it just fine. I tend to keep an eye on the temp for the transmission, so unless it's pushing well above 230 degress, I'm not too concerned about it. Even when I let the car sit for hours at a time running last Friday when I was on a job (it was a cold day to be outside), the transmission only got up to close to 220 F, and the analog gauge was barely past the halfway point.
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post #6 of 9 (permalink) Old 01-16-2017, 05:33 PM
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The hill start assist option only holds the brake while you move your foot over to the gas pedal when getting going uphill. It doesn't govern shifting once you are moving.

Grade shifting is a feature of the transmission, and it has an internal table that correlates percent grade, current speed, and torque output so that it will hopefully keep you in a gear that will allow you to go uphill without losing speed.
If you were able to upshift manually from the gear the computer chose, you would most likely begin losing speed because wheel torque at that gear/rpm wouldn't be enough to maintain speed at that incline.

This feature also works when going downhill and decelerating. If you are going downhill and begin decelerating, the transmission will automatically downshift to increase engine rpm and give you some engine braking.
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post #7 of 9 (permalink) Old 01-19-2017, 12:22 PM
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Originally Posted by sport_4x4 View Post
The hill start assist option only holds the brake while you move your foot over to the gas pedal when getting going uphill. It doesn't govern shifting once you are moving.

Grade shifting is a feature of the transmission, and it has an internal table that correlates percent grade, current speed, and torque output so that it will hopefully keep you in a gear that will allow you to go uphill without losing speed.
If you were able to upshift manually from the gear the computer chose, you would most likely begin losing speed because wheel torque at that gear/rpm wouldn't be enough to maintain speed at that incline.

This feature also works when going downhill and decelerating. If you are going downhill and begin decelerating, the transmission will automatically downshift to increase engine rpm and give you some engine braking.
Interesting because my 2016 cherokee seems to get majorly confused. When I know it should downshift and engine break it costs, and when I feel it should coast it engine breaks heavily. I bought this car to handle the mountains and I feel like it's going to explode going over small hills. I don't feel the engine should be hanging out at 4,000 RPMS for many minutes at a time until I can crest the hill.
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post #8 of 9 (permalink) Old 01-19-2017, 12:47 PM
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Originally Posted by sport_4x4 View Post
The hill start assist option only holds the brake while you move your foot over to the gas pedal when getting going uphill. It doesn't govern shifting once you are moving.

Grade shifting is a feature of the transmission, and it has an internal table that correlates percent grade, current speed, and torque output so that it will hopefully keep you in a gear that will allow you to go uphill without losing speed.
If you were able to upshift manually from the gear the computer chose, you would most likely begin losing speed because wheel torque at that gear/rpm wouldn't be enough to maintain speed at that incline.

This feature also works when going downhill and decelerating. If you are going downhill and begin decelerating, the transmission will automatically downshift to increase engine rpm and give you some engine braking.
And one more feature : when a certain angle is detected, the rear diff. is engaged (AWD ready).

No mountains where I live and drive, so I can't comment on the shifting patterns or efficiency. Not suprised by some of the comments though, the ZF9 is a querky beast (as in programmed by people high on something...).
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post #9 of 9 (permalink) Old 01-23-2017, 12:55 PM
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Interesting because my 2016 cherokee seems to get majorly confused. When I know it should downshift and engine break it costs, and when I feel it should coast it engine breaks heavily. I bought this car to handle the mountains and I feel like it's going to explode going over small hills. I don't feel the engine should be hanging out at 4,000 RPMS for many minutes at a time until I can crest the hill.
I think I was unclear in my post. When you are going downhill and hit your brakes in order to decelerate, grade shifting is activated and the transmission downshifts. If you are just coasting downhill, the transmission usually stays in the same gear. If you give it a little gas while downhill, it will usually upshift.
(Going downhill at ~75, giving a little gas and easing off is the only reliable way to get into 9th gear.)
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post #10 of 9 (permalink) Old 01-23-2017, 01:05 PM
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Originally Posted by Mark_ View Post
And one more feature : when a certain angle is detected, the rear diff. is engaged (AWD ready).

No mountains where I live and drive, so I can't comment on the shifting patterns or efficiency. Not suprised by some of the comments though, the ZF9 is a querky beast (as in programmed by people high on something...).
And to add even one more feature that is very useful when descending long grades, but isn't talked about often:

Putting the Cherokee in SPORT mode will give you better engine braking in two ways:
1. It tends to keep engine RPMs up
2. It opens and closes the intake manifold differently than AUTO, resulting in better engine braking. Apparently in AUTO the throttle body is closed in a way that maximizes efficiency by allowing you to coast farther.
I hope I'm not making the second part up because I can swear I read it in the manual a couple of years ago, but I don't remember which section it was in.
I could have dreamed it, but I go over the Santa Cruz mountains on hwy 17 at least twice a month and there is a specific section right after you crest the mountain where there is a decently long down grade and I have tried coasting in both SPORT and AUTO, starting at the same speed, in the same gear by using ERS, and when in SPORT, I actually have to give it a little gas at the halfway point so that I don't lose speed, where as in AUTO, I have to brake a little before the turn at the bottom so that I don't exceed the safe speed for that turn.
Now that could be the parasitic loss due to the rear diff being activated, but I figure the grade activates it anyway.
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