Cruise control surges/jerks downhill

Hey all,

 

I'm posting this on behalf of my grandparents. A while back they replaced their 98 legacy with an 05 legacy.

 

Immediately, they noticed a problem with the cruise control. Going down hills, the car surges/jerks while trying to maintain the correct speed. My grandpa thinks it's related to the new fly by wire system, and the systems are having trouble communicating.

 

They have taken the car to the dealer many times and have come to the conclusion that:

- Every similar car they drive has this problem

- No one else has complained about it, so it 'is not a problem'

 

They've gone to the factory with their problem and around March 20th got the following response.

 

Basically, what they are experiencing is a 'normal operating characteristic of the car.' The cruise control was only designed to work on FLAT, straight, level roads, not uphill or downhill. They also said they have duplicated this on other models, and since no one else has complained, it is not a problem in their eyes.

 

They also say to check the owners manual about the dangers of using cruise during inclement weather, lol.

 

If anyone else is having this problem, my grandparents advise going straight to the factory website to get all the problems reported in one place. Hopefully this way something will get done about it (if there turns out to be a true problem). If you want to email them about it, the address they used was SOAMail@sun.subaru1.com

 

 

So any comments? questions? Most of the cruise control problems I've found on this site relate to it shutting off after overheating.

 

Thanks a bunch.

well I noticed this happening to me as well, but I dont think its a problem.

I have an A/T. this happens when I set speed at about 100km/h, which is where the car shifts gear, so as a result it studders abit. thats my guess. I dont mind reporting a problem but probably they wont mind me since im in canada?!

lol, oh yea, I guess I should mention that they have the manual tranny, non-turbo, not sure about the specific model though.

 

edit: and every other car they've driven, including their previous subarus, have not had this problem.

funny you say that. i was going to ask about the same thing. my 05 l-gt 5spd surges/jerks when going downhill on cruise control (10k miles). a loaner non-gt 5eat had this "problem" also (6k miles). i was wondering if it was due to the electronic throttle, but, my 04 forester xt 5spd (25k miles) did not suffer from this condition. i have AP stg 1 now and it still does it. does anyone know why it feels so rough?

wait.. manual using CC ? I would imagine that the engine is bogging while going uphill (depends on the grade) because its expecting a downshift?

 

In an auto car.. the car would do a 4->3->4 shift if needed...

 

whereas the car is 'stuck' in a particular gear in a manual.

Since I live in "flatland" northern Indiana, I haven't seen this issue when the cruise is trying to maintain a steady speed.. However, I have noticed if the cruise is set and I want to "tap up" a few miles an hour that it will surge if I hit "accel" to rapidly... If I tap "accel" with a longer pause in between taps, it doesn't do it.

I use the cruize in my GT all the time on the highway. I set it at about 75 and go... uphill/downhill never noticed this symptom. At this speed the rpms are in the sweet spot for power and she flys up the hills no problem and coasts down the other side with no ill effects.

 

Does it happen as the car is exceeding the set speed due to steep grade? Or just trying to maintain the set speed?

 

As eamiller says, the power will surge on if you hold the accel stick or tap it rapidly.

I currently own both a 05 Outback XT and an 05 Legacy 2.5I, and strangely enough only the 2.5I has the problem with surging going downhill. It only happens on relatively steep hills where the car will accelerate with no throttle input. The Outback acts like nothing happens while the Legacy seems to take the "stab and release" approach. I might take the Legacy in to the dealer soon, but the Outback has to go in first, the brakes on that thing suck.

Yep, this happens my car ALOT... There are lots of hills and mountains here so I experience it quite a bit. 2.5i 5MT

 

Cheers

thanks for all the replies/confirmations of the problem. I'm also curious if you've had this problem personally in other cars.

 

anywho, I just got back an email from them with some more information.

 

They see it on gentle declines to much steeper declines. By gentle decline, they mentioned a local road that drops *maybe* 100 feet over a mile for a while - ie, not very steep.

 

They don't have any problem with it maintaining the correct speed going uphill, even on steeper roads.

Are you sure your not talking about the engine braking that occurs when you have the Cruise Control ON. It happens in most vehicles as its the system trying to maintain the speed which you have set.

Adam.

Moved to "Warranty Issues and Problems."

 

Thanks,

 

Kevin

I just bought a 2005 legacy 4 cylinder 4 speed automatic

and the cruise seems to be bucking when i go down hills.

 

 

 

It is amazing that after driving other vechicles on the dealers lot that has the same problem that more people have not complained to Subaru or if they did Subaru is not responding.

 

We current own a 1997 & 2002 that do not have this problem.

 

Where do you go to get someone, other than customer service, at Subaru to fix this?

 

I can't image that customer service is telling us that cruise is only for flat groudn; what a bunch of bull............every other vechile we have (ford) cruise works both on flat land and hills.

 

They really need to respond to this issue.

 

We have stopped driving our vechile until they resolve this issue.

call SOA, thats my best guess

and I did complain here but Im not sure if Subaru Canada reports things to SOA.

Seems to work fine for me. I tried it going through the Sepulveda Pass for the SoCal folks. Set it as I merged onto the 405 south from the 101 north/west and canceled it about when I got to Wilshire.

Having the same problem, 2.5iMT on a 2k trip from Arizona to Wyoming and back this was quite annoying. Going down any slope not even just major hills it jerks, so we have to put on the gas or kill the CC then resume... pain in the ass.. (one of my only complaints about the car)

 

It should just cruise down the hill or gradually slow the car down not jerk after jerk after jerk that can’t be a good thing on the car.

For anyone who is experiencing the cruise control nightmare in the 2005 4cyl, 4 spd automation as i am, please write to:

 

jmergen@subaru.com

 

please reference my case # 743944

 

Here is Deloria Marshall's response to my complaint:

Thank you for visiting the Subaru Web site and for taking the time to contact us. We apologize for the difficulties you have encountered regarding your 2005 Legacy I Limited Sedan.

 

Subaru of America, Inc. has determined that the cruise control operation that you have experienced is a normal operating condition. We are aware of this condition and we are confident the operation is not indicative of damage or defect within the cruise control system. We are working very closely with our service technical support regarding this matter.

 

She certainly has not driven one of these models with these comments.

The more people who write the better.

 

You can also reach her at 856-488-3206

 

Thank you,

Gary Morgan

i've felt it... however it's barely noticeable, and i would definitely not consider it 'a problem'.

 

Many other cars i've driven have similar characteristics when going downhill on cruise.

 

We have stopped driving our vechile until they resolve this issue.

 

man, i'm sorry -- but that is just excessive. If the cruise control really bothers you that much -- don't use it.

 

jeeze.

The problem doesn't exist in the '05 GT's 6cyl, so those owners don't know what we are talking about. Let them go drive 2005 Legacy I Limited Sedan 4spd auto, 4cyl, until then we are not comparing apples to apples.

 

While riding with a Subaru Tech yesterday, diagnosing a completely unrelated cruise control problem, I asked him about this. We were driving on the highway and it began to happen. He told me that it was completely normal and that it happens in all 5 speed cars with cruise and just happens to be more pronounced in the 05 legacy than most others.

 

Cheers

more pronounced in the 05 legacy than most others.

 

Cheers

 

that's why we're complaining... I mean its physics if you go up or down the car will try to maintain the same speed which causes such reaction. But y is it that obvious on the Legacy? That's the question I guess.

I'm not a mechanical engineer but I recall the Subaru tech having mentioned something about having more displacement/torque than most other cars so thats why it was so pronounced.

I have the same problem on my '05 Legacy Ltd 2.5i wagon with automatic transmission. It seems that instead of feathering in and out of the throttle the '05's cruise control just lifts completely and then stabs at the gas to try and maintain speed down hill. If the cruise control has as much trouble applying gas smoothly as the drivers sometimes do with the "drive by wire" throttle it's no wonder it lurches. The system is probably working as designed BUT if Subaru wants to even remotely hope that they are competing with upscale cars such as BMW or Audi such annoyances certainly won't help them achieve that goal. I really like the new Legacy's but they are full of little quirky thinks like this that can be a constant reminder that you are not driving a BMW !

Hey all, I have the same issue with my 2.5i automatic. The cruise control results in jerks if the road is not perfectly flat. I can't believe SOA used the excuse that cruise control is only for flat roads. This is my first Subaru and I'm VERY disappointed. All my previous cars have been Hondas/Acuras. I have NEVER experienced any of these problems with those cars.

However, the quirky thing is that the jerkiness was more pronounced when I first began to use the cruise control...the jerkiness subsided when I accumulated more mileage. It was almost as if the car was learning how to drive in cruise control...

 

Could this jerking be due to the fact that throttle is done without the use of a wire...therefore there isn't progression in throttle control?