Jerky Cruise Control?

[Kamauxx]

Someone (I haven't had time today to figure out who) said that Kia admitted to the problem and was working on the car to fix it. Anyone remember the outcome for that Stinger? So, while it has been 3 years, if Kia has recognized the problem, perhaps there is hope after all? I want a Stinger so bad but adaptive cruise control *must* work properly due to my disability. Please Kia, if you have anyone reading this forum, come out with a TSB for this. Please????

Take one (or more) for a test drive. The problem might not effect all Stingers. Or maybe you just won't even notice it. Couldn't hurt to try.

 

[JeffAsfbay]

Take one (or more) for a test drive. The problem might not effect all Stingers. Or maybe you just won't even notice it. Couldn't hurt to try.

That is, of course, a great idea. I do however want to buy a Stinger that hasn't been driven any further than off the boat/train/transport truck, and especially not any Kia dealer staff or customers taking the car for test drives. My concern is simple - because the Stinger is so fun to drive and is faster than any car most folks have ever driven, this can lead to test drivers beating the car and certainly not observing the break-in rules. This just means, I guess, that I need to create a relationship with someone at my closet dealer so that (s)he can call me when new deliveries arrive.

 

[P22Tyler]

Someone (I haven't had time today to figure out who) said that Kia admitted to the problem and was working on the car to fix it. Anyone remember the outcome for that Stinger? So, while it has been 3 years, if Kia has recognized the problem, perhaps there is hope after all? I want a Stinger so bad but adaptive cruise control *must* work properly due to my disability. Please Kia, if you have anyone reading this forum, come out with a TSB for this. Please????

I have an '18 GT2 and have zero problems with the adaptive cruise control, it works perfectly. And I believe that Kaumaxx's car didn't even have adaptive cruise if I read his posts correctly.

 

[vipeboy2000]

i also don't have the adaptive cruise and have noticed the slight "pulsing" of the cruise control.. if you pay attention to it it's a little annoying but now that we have almost 9k miles on it, i barely notice it.. I don't think it can't keep the speed, i think it tries to hard to not deviate so it's making noticeable micro adjustments rather than there being a small buffer for the speed to feel smooth..

 

[EClapp3]

Someone (I haven't had time today to figure out who) said that Kia admitted to the problem and was working on the car to fix it. Anyone remember the outcome for that Stinger? So, while it has been 3 years, if Kia has recognized the problem, perhaps there is hope after all? I want a Stinger so bad but adaptive cruise control *must* work properly due to my disability. Please Kia, if you have anyone reading this forum, come out with a TSB for this. Please????

It works fine, it just stays around the set speed and goes up and down a bit.

 

[mattbrac3]

I’ve noticed this as well. Not sure why but not a huge concern.

 

[stoopid]

Anyone else notice the car jerking/lurching when cruise is enabled?
...
It feels like the computer is having a hard time making fine adjustments to the throttle bottle.

Yup, it's just not a very sophisticated cruise system. Noticed it first time, and every time, since buying my '21 GT.

 

[Mikedfw]

Use mine all the time on the freeway and in school zones and works fine, haven't noticed any jerkiness. I've used adaptive cruise control in fords, mazdas and kias. I'd say it's better than fords and about the same as the mazda, maybe a little better.

 

[JeffAsfbay]

It works fine, it just stays around the set speed and goes up and down a bit.

How much is "a bit?" With the greatest respect, unless "a bit" is <1 mph or it only fluctuates on hilly roads, then I have to disagree with your assertion that it's working fine.

The post above mine is from someone who says it works fine, so I'm still trying to wrap my engineering mind around this potential problem. If it were a design flaw, such as using an A/D or D/A with inadequate resolution or one of multiple sensors are intermittent (or I don't know what else & I'm open to suggestions), it ought to be present in everyone's Stinger (and if the adaptive/standard cruise control is a standard design copied and implemented exactly the same way in every Kia and Hyundai vehicle, other vehicles should have similar symptoms - and we've had at least one person post that a different Kia shows the same problem.)

So since that doesn't seem to be the case, what are the possible differences in assembly such that many Stingers seem to *not* be afflicted with the much discussed symptoms (i.e., jerky cruise control)?

- The Stinger is drive-by-wire so there is no traditional throttle
linkage that might be binding, right?
- But there could be a cable and/or linkage closer to the throttle
body that could be binding?
- Or maybe a weak actuator/motor that changes throttle body
position?
- Or a misaligned sensor measuring current throttle body position?
- Or actually, since the engine is direct injected, is there a throttle
body? Some websites say there doesn't have to be
(Gasoline Direct Injection),
but in searching specifically for the 3.3L turbo V6 in the Stinger,
I find information about about a larger bore aftermarket TB
(2018+ Stinger 3.3 Turbo Big Bore Throttle Body.)
- And I suppose that throttle mapping and/or changes of air/fuel mixture could somehow enter into the equation?
- Too much hysteresis in the control loop?
- Any other ideas people want to share (besides that people are imagining the problem)?

If the person who posted that Kia was actually working on their Stinger to fix the problem could post an update, that would be fantastic! (Or if they already did, please post a link.)

Thanks everyone.

 

[EClapp3]

How much is "a bit?" With the greatest respect, unless "a bit" is <1 mph or it only fluctuates on hilly roads, then I have to disagree with your assertion that it's working fine.

The post above mine is from someone who says it works fine, so I'm still trying to wrap my engineering mind around this potential problem. If it were a design flaw, such as using an A/D or D/A with inadequate resolution or one of multiple sensors are intermittent (or I don't know what else & I'm open to suggestions), it ought to be present in everyone's Stinger (and if the adaptive/standard cruise control is a standard design copied and implemented exactly the same way in every Kia and Hyundai vehicle, other vehicles should have similar symptoms - and we've had at least one person post that a different Kia shows the same problem.)

So since that doesn't seem to be the case, what are the possible differences in assembly such that many Stingers seem to *not* be afflicted with the much discussed symptoms (i.e., jerky cruise control)?

- The Stinger is drive-by-wire so there is no traditional throttle
linkage that might be binding, right?
- But there could be a cable and/or linkage closer to the throttle
body that could be binding?
- Or maybe a weak actuator/motor that changes throttle body
position?
- Or a misaligned sensor measuring current throttle body position?
- Or actually, since the engine is direct injected, is there a throttle
body? Some websites say there doesn't have to be
(Gasoline Direct Injection),
but in searching specifically for the 3.3L turbo V6 in the Stinger,
I find information about about a larger bore aftermarket TB
(2018+ Stinger 3.3 Turbo Big Bore Throttle Body.)
- And I suppose that throttle mapping and/or changes of air/fuel mixture could somehow enter into the equation?
- Too much hysteresis in the control loop?
- Any other ideas people want to share (besides that people are imagining the problem)?

If the person who posted that Kia was actually working on their Stinger to fix the problem could post an update, that would be fantastic! (Or if they already did, please post a link.)

Thanks everyone.

In my experience it fluctuates about +- 1 mph up and down hills on the highway. Which yes is annoying but its not detrimental, it still slows down and speeds back up on its own with traffic just fine.

There are no linkages, its all motors, gears, and sensors.

Yes there is a throttle body, there has to be a throttle body. There isn't TBI (throttle body injection) but there has to be a throttle body.

I have no clue what the problem is or could be. But I do know that stuff^

 

[JeffAsfbay]

In my experience it fluctuates about +- 1 mph up and down hills on the highway. Which yes is annoying but its not detrimental, it still slows down and speeds back up on its own with traffic just fine.

There are no linkages, its all motors, gears, and sensors.

Yes there is a throttle body, there has to be a throttle body. There isn't TBI (throttle body injection) but there has to be a throttle body.

I have no clue what the problem is or could be. But I do know that stuff^

Thanks for your input - fluctuating on hilly roads/freeways is expected and completely acceptable in my mind. It's the jerkiness on flat roads that bothers me.
And thanks for verifying that there is a throttle body (which I figured had to be true when I found the larger bore aftermarket TB.) I was thrown off by the link I provided saying there doesn't have to be - how does one control the amount of air without one?

 

[P22Tyler]

In my experience it fluctuates about +- 1 mph up and down hills on the highway. Which yes is annoying but its not detrimental, it still slows down and speeds back up on its own with traffic just fine.

There are no linkages, its all motors, gears, and sensors.

Yes there is a throttle body, there has to be a throttle body. There isn't TBI (throttle body injection) but there has to be a throttle body.

I have no clue what the problem is or could be. But I do know that stuff^

Every vehicle will fluctuate at least +-1 mph, the car would have to be able to predict even the slightest changes in the angle of the road and make proactive changes to prevent this from happening. In my experience this car doesn't go any further than that. My car has never had issues with keeping up with whatever speed I set. It's the best car I've ever owned for climbing hills with the cruise on, and living in Utah we've got some serious hills. I wouldn't even bother using the cruise on inclines with previous cars.

As far as I can tell from what everyone has posted on here, it seems like only the non-SCC (Smart Cruise Control) cars have the problem of jerking. If that is incorrect, someone please let us know. I'm not sure how much of the cruise control system is the same, but I'm not sure it matters if everyone else with SCC has had no problems. It sounds like you would be going for a SCC car @JeffAsfbay so you should not have to worry about the problem of the car jerking.

 

[EClapp3]

Thanks for your input - fluctuating on hilly roads/freeways is expected and completely acceptable in my mind. It's the jerkiness on flat roads that bothers me.
And thanks for verifying that there is a throttle body (which I figured had to be true when I found the larger bore aftermarket TB.) I was thrown off by the link I provided saying there doesn't have to be - how does one control the amount of air without one?

Exactly it fluctuates a hair but it is slightly jerky while doing it, nothing like whiplash but just enough to be noticeable and add in the HUD makes it even more obvious.
Yes exactly, the throttle body is there to regulate airflow. There is one on everything, idk what you read saying there wasn't one.

Every vehicle will fluctuate at least +-1 mph, the car would have to be able to predict even the slightest changes in the angle of the road and make proactive changes to prevent this from happening. In my experience this car doesn't go any further than that. My car has never had issues with keeping up with whatever speed I set. It's the best car I've ever owned for climbing hills with the cruise on, and living in Utah we've got some serious hills. I wouldn't even bother using the cruise on inclines with previous cars.

As far as I can tell from what everyone has posted on here, it seems like only the non-SCC (Smart Cruise Control) cars have the problem of jerking. If that is incorrect, someone please let us know. I'm not sure how much of the cruise control system is the same, but I'm not sure it matters if everyone else with SCC has had no problems. It sounds like you would be going for a SCC car @JeffAsfbay so you should not have to worry about the problem of the car jerking.

That's what I'm saying is that it is perfectly acceptable IMO how much it fluctuates. I have no problems with it.

 

[P22Tyler]

Ultimately as someone else suggested @JeffAsfbay you're going to have to drive one. Find one you want to buy, tell them your concerns so that they'll let you drive the car in a situation where you can test the cruise control thoroughly, and see how it feels to you.

 

[stoopid]

I have non-"Smart" cruise (non-adaptive). It handles things fine, generally. But it has a bit of a lurching effect when it needs to adjust to the set speed.

It's not a flaw, it's similar to other cruise I've used in cheaper model cars. I assume they've part binned the cruise system from their other models, which are of course 'cheaper' cars. In contrast, my prior 2 Buicks were smooth at making the adjustments but would fall further out of the set range. This might indicate the issue is the low tolerance (maybe only allowing 1 mph difference) forcing the Stinger to be constantly busy trying to match the set speed, instead of making smaller incremental changes and eventually getting there.

 

[rpoffen]

And thanks for verifying that there is a throttle body (which I figured had to be true when I found the larger bore aftermarket TB.) I was thrown off by the link I provided saying there doesn't have to be - how does one control the amount of air without one?

Actually, Fiat's MultiAir system does just that. It is a hydraulic variable valve lift system that eliminates the throttle body by controlling how much the intake valve opens. You can look it up on Wikipedia.

 

[EClapp3]

Actually, Fiat's MultiAir system does just that. It is a hydraulic variable valve lift system that eliminates the throttle body by controlling how much the intake valve opens. You can look it up on Wikipedia.

Theres always one lol. Other than the crazy off the wall normal stuff there is always a TB

 

[rpoffen]

Not as off the wall as you might think, the Fiat 500's and most of the small jeeps use it.

 

[Mesmorino]

If I'm going at 60km/h, and set the cruise control to 65, it will accelerate up to 70, then ease off the throttle to 63ish, then boost again until 67, lurching and jerking until it gets to 65 unless I quit it first which I almost always do to avoid running into the back of the car ahead. I don't have adaptive CC, it's a MY2019 GT Limited (Canadian 2L).

It only ever happens when the CC is set to close to the speed I'm already going, leading me to believe it just struggles with fine adjustments. If I'm going at 64 and set CC to 65, it's fine. It'll hold at 64 or even 66. If I'm at 40 and set it to 65, it'll accelerate smoothly up to 64ish, and hold there.

But if I'm doing 60-63 and set CC to 65, it happens. Not all the time either, it's very unpredictable. Happens on flats, hills, uphill or downhill. I've just taken to using it to hold my speed (accelerating myself), rather than letting CC get up to my desired speed.

 

[vipeboy2000]

If I'm going at 60km/h, and set the cruise control to 65, it will accelerate up to 70, then ease off the throttle to 63ish, then boost again until 67, lurching and jerking until it gets to 65 unless I quit it first which I almost always do to avoid running into the back of the car ahead. I don't have adaptive CC, it's a MY2019 GT Limited (Canadian 2L).

It only ever happens when the CC is set to close to the speed I'm already going, leading me to believe it just struggles with fine adjustments. If I'm going at 64 and set CC to 65, it's fine. It'll hold at 64 or even 66. If I'm at 40 and set it to 65, it'll accelerate smoothly up to 64ish, and hold there.

But if I'm doing 60-63 and set CC to 65, it happens. Not all the time either, it's very unpredictable. Happens on flats, hills, uphill or downhill. I've just taken to using it to hold my speed (accelerating myself), rather than letting CC get up to my desired speed.

That is very interesting as we have never experienced that behavior. Regardless of speed and how close we are to the speed we set it is very good at maintaining that speed. The only thing I notice is the very very tiny little pulses of throttle on flat ground when it is maintaining the speed. If anything it feels like it is keeping the speed too locked down and if it let a little freedom on speed it wouldn't be as touchy feeling . Mind you this is so slight that no one riding with me says they can feel it .. really only the one driving can tell if they are paying attention.