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2018 2.5 premium. I love this car and think it is the best outback I have ever owned. One of my favorite features is th ACC which I think operates extremely well and smoothly. However, I am disappointed in how the cruise operates when encountering uphill grades. I have found that when cruising anywhere from 50-80mph and coming to a hill my engine races extremely high with rpms spiking up to 5k+. I am not in the comfortable with my engine cranking this hard, so I have developed the habit of switching off cruise at every uphill I encounter. When I disengage cruise control prior to hitting a hill and drive by foot, I am easily able to maintain speed at 70mph+ with rpms not exceeding 3800 or so.

Anyone else experiencing this? Possible solution ideas? Is it worth trying a cvt reset, or bringing to dealership for software update?
 

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2019 OB 3.6R Limited, and 4 VW TDI bugs.
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117 Posts
Mine does the same thing so on steeper hills, I take over from cruise control to maintain a more acceptable RPM range.
 

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2017 Outback 2.5i Limited
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This has happened on almost every car I've owned. Even a Dodge Ram 1500 with a 5.7L V8. I always just switch off cruise on hilly sections. I like to manually control my throttle on those sections.
 

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2016 Tungsten Outback 2.5l Premium w/ES, OP 14, PP #4
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500 Posts
Well there is a TSB for it for old vehicles. It happens on my 16 too and I'm thinking about telling the dealer to apply the fix next time I go in

https://subaru.oemdtc.com/347/tcm-reprogramming-for-rpm-flare-and-cruise-control-operation-2015-2016-subaru-legacy-outback
According to the info in the service bulletin my '16 should have the newer logic. (VIN >G2946684) I still experience a rpm flare as described. However the extent is dependent on several factors. I've gotten used to it's behavior and select when to disengage the cruise control to stay in my comfort zone. Cruise control's main goal is to maintain the speed you set. When I disengage CC I don't mind going a little slower to lower engine rpm.
Thx for the info BTW
 

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2017 2.5i Premium Lapis Blue
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Despite the thread title the Subaru ACC isn't in any way meant to be "smart". All it can do is recognize the presence of a vehicle in the same lane ahead and adjust speed to keep the set distance. It doesn't "see" things like hills or long uphill grades and accordingly doesn't adjust for them. All the cruise control knows is that if the car meets increased resistance it is supposed to apply throttle to keep the set speed, and it will do so aggressively. This is why it is possible to get better mileage without the cruise control than with it. Of course the key word there is "possible".


The day probably isn't far off when cruise controls will have a lot more input data that it will be able to use to regulate speed more smoothly in different situations, but it isn't here yet.
 

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'18 Outback Limited/Ex: 2000 Outback Limited
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Despite the thread title the Subaru ACC isn't in any way meant to be "smart". All it can do is recognize the presence of a vehicle in the same lane ahead and adjust speed to keep the set distance. It doesn't "see" things like hills or long uphill grades and accordingly doesn't adjust for them. All the cruise control knows is that if the car meets increased resistance it is supposed to apply throttle to keep the set speed, and it will do so aggressively. This is why it is possible to get better mileage without the cruise control than with it. Of course the key word there is "possible"...

Well stated!


Bill
 

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Well stated!


Bill
Yes, but it doesn't address the OPs concern of the engine racing on hills. I think he would still have the problem even if the smart feature is turned off.


Not a big deal for my Outback because I have a 3.6, but my wife felt some revving while test driving the turbo 2.4 Ascent. So, I'm watching this thread.


Beary
 

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2018 Legacy 36R
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Find another OB equipped with the same engine/transmission as yours and test drive it on one of the same hills. You could have a CVT problem. I don't think it is the CC, the CC is just trying to do its job which is to keep the set speed.
 

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2020 Hyundai Santa Fe Limited 2.0 T AWD
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Mine has worked flawlessly, and it's a God send in stop n' go traffic. At the same time I only use it on highways and interstates. Not during urban driving, not up two lane mountain passes, not on on and off ramps. Basically I use it with a little common sense. It's just another set of eyes. And where it takes the workload off me as a driver.
 

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'18 Outback Limited/Ex: 2000 Outback Limited
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Yes, but it doesn't address the OPs concern of the engine racing on hills. I think he would still have the problem even if the smart feature is turned off.


Not a big deal for my Outback because I have a 3.6, but my wife felt some revving while test driving the turbo 2.4 Ascent. So, I'm watching this thread.


Beary

Sorry for any misunderstand. I was only agreeing about his explanation of how 'cruise control'. As to the OP's problem/question, I'm following to see what that all about (like everyone else).


Bill
 

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Well there is a TSB for it for old vehicles. It happens on my 16 too and I'm thinking about telling the dealer to apply the fix next time I go in

https://subaru.oemdtc.com/347/tcm-reprogramming-for-rpm-flare-and-cruise-control-operation-2015-2016-subaru-legacy-outback
I had this flashed to my 2015 2.4 Outback at last dealer visit.

I'm certain this helped rpm flare.

My test track is I70 west of Denver. In moderate traffic you need to maintain 65 to 70 mph on steep upgrades, whether in adaptive cruise or foot on the pedal, traffic doesn't allow you any slack to set your own pace.

Previously I would see flare to 5.5k on heavy load, today it stayed in the 4.5k range consistently.

I'm convinced it changed engine behavior. Deceleration and engine braking in adaptive on downgrades was still excellent.

I didn't have opportunity to test manual downgrade braking. I've always found adaptive to be more effective at downhill engine braking compared to manual.

Fwiw ...
 
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