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post #11 of 22 (permalink) Old 10-21-2016, 11:48 AM
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Originally Posted by aaridici View Post
I had an opposite experience just recently where the car was aware that I was going downhill and engaged a lower gear to maintain the cars speed without requiring breaking from me. A very steady 40mph without driver breaking in a not-that steep but kinda situation. As soon as the road flattened, it shifted up. It was an interesting experience. In 2 years, this is the only time I noticed it. An anomaly perhaps but a good one.
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Originally Posted by aaridici View Post
Cruise control was off. I had the car in cruise control downhill before. It accelerates quite a bit before engine breaking starts. It wasn't anything like it. It was almost like it thought I was going down a very steep hill and engaged something like hill descent assist (what it would be in other high end SUVs).
That's interesting. The 9-speed will be more busy than transmissions with fewer gears. We know it downshifts as the vehicle decelerates, but usually it's not perceivable. Who knows what gets in the 9-speed's computer head. I'm in ACC most of the time which is probably why I haven't noticed what you did.

I looked up references to 'downhill' in the owner's manual and found these:

When descending mountains or hills, repeated braking
can cause brake fade with loss of braking control. Avoid
repeated heavy braking by downshifting the transmission
whenever possible.

Using Electronic Speed Control On Hills
The transmission may downshift on hills to maintain the
vehicle set speed. The Electronic Speed Control system maintains
speed up and down hills. A slight speed change on
moderate hills is normal.

The ACC system maintains set speed when driving up
hill and down hill. However, a slight speed change on
moderate hills is normal. In addition, downshifting
may occur while climbing uphill or descending downhill.
This is normal operation and necessary to maintain
set speed. When driving up hill and down hill, the
ACC system will cancel if the braking temperature
exceeds normal range (overheated).
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post #12 of 22 (permalink) Old 10-21-2016, 02:11 PM
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Since I don't have Active cruise control, it has to be Electronic Speed Control On Hills. But it is surprising that it happened last week for the first time on a road that I traveled many many times at the exact same speed. I haven't had updates in at least 6 months.
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post #13 of 22 (permalink) Old 10-21-2016, 02:45 PM
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I vaguely remember reading somewhere in the manual that in auto, the way either the valves, or the intake manifold opens and closes is set for efficiency, but has the effect of reducing engine braking.
The manual recommended switching to SPORT mode for more effective engine braking.
I have found this to be true. For a given gear,engine RPM, and downhill grade, there is better engine braking in SPORT mode than in auto.

I use SPORT in combination with the ERS for optimal engine braking.
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post #14 of 22 (permalink) Old 10-21-2016, 03:41 PM Thread Starter
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I appreciate the replies. Mine is a v6, this occurs while cruise control is off and I don't have ACC. I will respond to Jeep Cares and see if they have any ideas. My vehicle has not been serviced yet and this is pretty much my only complaint except for slightly loose interior rearview mirror. Not exactly a laundry list of complaints, very satisfied so far.
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post #15 of 22 (permalink) Old 10-21-2016, 05:41 PM
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.... I will respond to Jeep Cares and see if they have any ideas. My vehicle has not been serviced yet and this is pretty much my only complaint except for slightly loose interior rearview mirror. Not exactly a laundry list of complaints, very satisfied so far.
Hope you get good technical feedback from an engineer and can share it with us. It's entertaining to get good info on how this amazing machine works.

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post #16 of 22 (permalink) Old 10-21-2016, 06:00 PM
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As long as Skynet is not hacking your jeep I you should be ok. I pull a 21' 3,500 lb travel trailer allot. With regular cruise control there is limited engine breaking. I have had it sport mode going down a long grade and had some high tran temps and had to go back to auto setting to let it cool. with a smaller displacement engines with fuel saving valve settings engine braking will be an issue. more of a beware of the conditions and take it easy down those grades. A mix of breaks and down shifting and slower speeds will be the best way to handle steep highway down grades with a load.

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post #17 of 22 (permalink) Old 10-21-2016, 06:08 PM
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Originally Posted by Pondhopper View Post
As long as Skynet is not hacking your jeep I you should be ok. I pull a 21' 3,500 lb travel trailer allot. With regular cruise control there is limited engine breaking. I have had it sport mode going down a long grade and had some high tran temps and had to go back to auto setting to let it cool. with a smaller displacement engines with fuel saving valve settings engine braking will be an issue. more of a beware of the conditions and take it easy down those grades. A mix of breaks and down shifting and slower speeds will be the best way to handle steep highway down grades with a load.
Do you remember what temperatures you were experiencing? I don't think the transmission cooler even turns on under 200 degrees.
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post #18 of 22 (permalink) Old 10-21-2016, 06:11 PM
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The system was reading 212° to 230° I think it was almost a year ago. It did not get to the red line but was going up at a fast rate.

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post #19 of 22 (permalink) Old 10-21-2016, 07:09 PM
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Originally Posted by prg View Post
I pm'd JeepCares quite some time ago and I guess they really don't so I will try here, as I never got a response. I have a 2016 TH, about 3k miles. When I try downshifting for downhill deceleration I find that the rpm's oscillate up and down from about 1000 to 2500 and the vehicle accelerates and decelerates accordingly, kind of unnerving and not very effective for engine braking. I am used to using engine braking in mountain driving and particularly concerned about relative lack of this, especially if pulling a trailer. Anyone note similar behavior or have any suggestions?
Just use your brakes. As my brother in law once pointed out to me....brakes are relatively cheap compared to replacing a worn clutch or automatic transmission.
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post #20 of 22 (permalink) Old 10-21-2016, 07:14 PM
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My Cherokee offers up practically no engine braking so I stopped asking for it. It does however, sometimes stick in a lower gear when I am descending a long hill and it helps to maintain a maximum speed. I have yet to figure out what combination of inputs from myself, actually trigger this speed control. I just know it hapens sometimes on certain hills and it stays that way until I hit the gas, at which point it shifts gear and takes off like a bat out of ****......in spite of the inline 4 I have, which 've been led to believe by this forum, is anemic and a waste of engine bay space.
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