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  #13  
Old 11-08-2013, 01:17 PM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by marosenb View Post
Had mine in for repairs about 3 weeks ago, and they also did the most recent trans flash: Since then, mine also behaves similarly. When I leave my house, I immediately have about 1 mile at a decent decline: I'll be going about 30 MPH, and it jumps to 4K rpms. happens about 1/3 of the time. If I don't hit the brakes or gas, it will continue for the whole mile, and the engine sounds pretty damn loud. Dealer says it is the trans trying to engine break to avoid gaining too much speed going downhill. Not sure how much I buy that.
About as much as you'd buy
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  #14  
Old 11-08-2013, 05:28 PM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by lstowell View Post
It isn't at all desirable if that changes the loading on the drive wheels on a slippery surface, unless one is a liability lawyer looking for a new BMW budget.

There are those who argue that the worst set of brakes on any modern non-commercial truck/vehicle tend to be better than the rest of the drive train and a heck of a lot cheaper and easier to replace due to the inevitable wear and tear.

I have to disagree ...
On a slippery surface you would avoid at all costs to step on your brakes, therefore if you are going downhill on a slippery surface and need to reduce or maintain your speed I wouldn't step on brakes ,I definitely use engine braking.

Engine braking by no means would reduce your grip on the road ...Actually it is quite the opposite. If you see some racing on TV .. you'll see that drivers do this all the time on all situations where braking is required ...
I can understand that you don't like the feature ... and I'm not saying Jeep has the best algorithm to do this, may be too abrupt .. but on a descent, engine braking is the way to go! We are not talking about wear and tear of components .. we are talking about safety!
Many people just apply a slight pressure on their brakes to control the speed and rest their foot on the brakes for the entire descent... at the end of the hill they might need full power on the brakes for some reason when they realize they don't have any due to overheating them for miles.

Again this is for safety .. not to save components ...
We might know how to switch between engine braking and regular brakes and might not even need this feature .. but I can guarantee that most drivers won't do it...
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Old 11-08-2013, 05:57 PM
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Re: 2014 Overland 3.6 weird downshift

If you don't have cruise control set, how does the Jeep determine that you don't want to be going 90 mph down that steep hill.


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Old 11-08-2013, 08:01 PM
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Originally Posted by FAST_US View Post

I have to disagree ...
On a slippery surface you would avoid at all costs to step on your brakes, therefore if you are going downhill on a slippery surface and need to reduce or maintain your speed I wouldn't step on brakes ,I definitely use engine braking.

Engine braking by no means would reduce your grip on the road ...Actually it is quite the opposite. If you see some racing on TV .. you'll see that drivers do this all the time on all situations where braking is required ...
I can understand that you don't like the feature ... and I'm not saying Jeep has the best algorithm to do this, may be too abrupt .. but on a descent, engine braking is the way to go! We are not talking about wear and tear of components .. we are talking about safety!
Many people just apply a slight pressure on their brakes to control the speed and rest their foot on the brakes for the entire descent... at the end of the hill they might need full power on the brakes for some reason when they realize they don't have any due to overheating them for miles.

Again this is for safety .. not to save components ...
We might know how to switch between engine braking and regular brakes and might not even need this feature .. but I can guarantee that most drivers won't do it...
As you mention it's not engine braking that reduces grip, it's very sudden engine braking that creates a drastic change in wheel speed in low grip scenarios such as snow that would be a problem.

I'm not for or against it, Very far out scenario in my opinion... Having driven manuals my whole life I just know when I want engine brake and when I don't... Damn you jeep why you no read my mind.
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  #17  
Old 11-08-2013, 09:00 PM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by bill_de View Post
If you don't have cruise control set, how does the Jeep determine that you don't want to be going 90 mph down that steep hill.


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That was my first question to myself. Then I got to thinking that the Jeep has three data points necessary to trigger the Nanny downshift; how fast, is the car picking up speed and is the throttle being applied.

If the Jeep is accelerating with no throttle being applied then the Nanny determines that the Jeep is going downhill sans any speed retardant, hence the downshift.

I should emphasize that, in my case, the downshift did not result in any abrupt event in the drive train. In fact, the only evidence I had that something had happened was the sound of the engine rpm increasing. Nothing like what would happen if you geared down too low and dumped the clutch.
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  #18  
Old 11-08-2013, 09:05 PM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by TurboRush View Post
As you mention it's not engine braking that reduces grip, it's very sudden engine braking that creates a drastic change in wheel speed in low grip scenarios such as snow that would be a problem.

I'm not for or against it, Very far out scenario in my opinion... Having driven manuals my whole life I just know when I want engine brake and when I don't... Damn you jeep why you no read my mind.

A couple of things come to mind here. One is that the downshift I experienced was no where near abrupt with respect to traction. It seemed to know what gear was necessary to retard further acceleration.

The other is that we don't know whether Nanny downshifting is in the Snow program. Then again, motoring down the descent I was on at 70 in snow just might be more than anyone has a right to expect out of any vehicle.
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Old 11-09-2013, 04:48 PM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by bill_de View Post
If you don't have cruise control set, how does the Jeep determine that you don't want to be going 90 mph down that steep hill.
If throttle is not being applied .. there is only one force that can move your truck ... gravity (except if you are being towed )
So the algorithm checks that you are gaining speed with no throttle and just downshift it...
But if you are going downhill applying throttle ... don't rely on the system to brake ... your truck will go all the way down


Quote:
Originally Posted by TurboRush View Post
As you mention it's not engine braking that reduces grip, it's very sudden engine braking that creates a drastic change in wheel speed in low grip scenarios such as snow that would be a problem.

I'm not for or against it, Very far out scenario in my opinion... Having driven manuals my whole life I just know when I want engine brake and when I don't... Damn you jeep why you no read my mind.
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Unless you are experiencing a huge straight downshift from 7th gear to 3th gear .. I don't think it will be so abrupt to put you in danger.. This would be a completely erratic behavior. Like if the truck wants to brake your car by itself which would lead to a drastic reduction in speed ... .. I don't think this is the purpose ...


The system is not designed to reduce speed .. it is designed to control speed. In other words .. it is just to avoid the use of brakes to maintain speed in a scenario where no throttle is being applied and still the truck is gaining speed. If someone experiences an abrupt speed reduction .. I would say ... yes! the system is completely flawed but I don't think this is the case. I guess people just find it weird and don't like that the truck is taking some action without asking us if we agree !!! These cars and trucks nowadays think they are smart than us!!

I was reading the Autoblog 2014 GC review and it says that this tranny has 90 algorithms to try to predict what we want from them. But you know there are so many factors, so many different situations, different driving styles .. It has improved a lot .. but it will take sometime to get to the point that trannies will read our minds ...
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Old 11-09-2013, 05:17 PM
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Re: 2014 Overland 3.6 weird downshift

When I was young and foolish, instead of old and foolish, we used to see how fast we could get our cars to go, down hill, without touching the gas. And, also see who could go the furthest without touching the brakes.

We didn't do this all the time. Just coming down off Bear Mountain, on the east side of the Hudson River. The hill is not only steep, but winds around with many sharp curves. The guard rail back then were a series of boulders.

Jeep, it seems, is trying to take the fun out of life ... And death.
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Old 11-09-2013, 05:23 PM
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Re: 2014 Overland 3.6 weird downshift

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Jeep, it seems, is trying to take the fun out of life ... And death.
Hey Bill...Just thank God we had the opportunity to live during a time when "Big Mother" wasn't trying to control everything, and we could experiment with the world, and natural selection still worked!
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  #22  
Old 11-11-2013, 06:31 AM
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Re: 2014 Overland 3.6 weird downshift

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Originally Posted by bill_de View Post
When I was young and foolish, instead of old and foolish, we used to see how fast we could get our cars to go, down hill, without touching the gas. And, also see who could go the furthest without touching the brakes.

We didn't do this all the time. Just coming down off Bear Mountain, on the east side of the Hudson River. The hill is not only steep, but winds around with many sharp curves. The guard rail back then were a series of boulders.

Jeep, it seems, is trying to take the fun out of life ... And death.
We all still can, lets get together and try it out.... Just put it in Neutral first!

btw, read through all of this and it all makes perfect sense to me, my Mercedes and most of the European cars have been doing this for years.
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