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Jerky automatic transmission shifting

Discussion in 'Engine, Drivetrain, and Exhaust Discussion' started by stingertig, Feb 17, 2018.

  1. stingertig

    stingertig Canada Newish Member

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    Most of the time my automatic transmission shifts very smoothly when in D mode. However occasionally the shifts are unpleasantly jerky. I haven't been able to figure out what exactly triggers it, there is no consistency in the behavior, except that it mostly happens under light acceleration (on the contrary when accelerating hard the shift are smooth, quick and nice). It also seems to happen a bit more often with cold engine.

    Did anyone else notice anything similar? This happens quite rarely so I am hesitant yet to drive to my dealership since I (they) may not be able to reproduce it easily.

    (This is 3.3 GT AWD in ECO mode).
     
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  2. Jesse

    Jesse Canada Member

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    Yeah, I get the same thing in comfort mode. Same parameters - slow acceleration from a cold start. As soon as it warms up it goes away and shifts perfectly smooth.

    I knew from reviews that the transmission wasn't as high quality when it comes to shift speed and gear transition as compared to Audi or BMW, but those cars have dual clutch transmissions, whereas the Stinger has a torque converter, planetary gearbox.

    I believe the torque converter was intended for longevity and reliability, since they use the same transmission (I think?) in the Sedona and Sorrento - vehicles that have a substantial towing capacity.

    So they've taken the same tow-ready transmission and stuck it in a sports sedan. Tuned as it is for performance, those hard hitting shifts may just be a product of this interesting union.

    If I find the transmission starts slipping a gear, or the shifts become rough and noisy at operating temperature, that's when I'll take it in to have it looked at.
     
  3. Jesse

    Jesse Canada Member

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    I've also noticed a slight hard-hitting shift in comfort mode, even when the car is warmed up. When accelerating near to 50kmh (speed limit), letting pressure off the accelerator, and at the same time the transmission performs an up-shift, there's a bit of a "throw" into the higher gear, which causes a touch of jerk. I don't think it's anything to be concerned about, though, unless someone more mechanically inclined could explain otherwise?
     
  4. upsidedown

    upsidedown Australia Active Member

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    Yes I agree as well as with the previous posts about the jerkiness. One other thing I've noticed when driving around especially in an urban 50 kmh area is the way the transmission downshifts when slowing down for an intersection. I know they probably calibrated it that way to use the engine as a brake and also get the car in the correct gear for that speed but it is a bit annoying. Sometimes it even feels like the car speeds up slightly as you are trying to slow down while the transmission goes though the shift change between gears and loses the engine braking effect. You can't even use manual mode to lock it in a gear as it still starts to downshift on its own even within the 10 second manual window. WTF? I think a better approach would have been to have it shift after the accelerator was pressed to speed up again rather than when you are tring to slow down. I really hope they alter the factory ecu settings with a service reflash or someone comes up with some aftermarket solution.

    PS BMW may have some dual clutches but they also use the ZF gearbox with a torque converter which is smoother or at least calibrated better than the KIA one
     
    Last edited: Feb 18, 2018
  5. musawi

    musawi Bahrain Newish Member

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    I have experienced this same issue. My car has been at the dealer for a couple of days. Waiting to see whether or not they can get this fixed and what is causing the problem.
     
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  6. Kia Stinger

    Kia Stinger United States Administrator Staff Member

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    Thank you. Please keep us posted on what the dealer finds. Welcome to the community!
     
  7. musawi

    musawi Bahrain Newish Member

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    The dealer ended up reprogramming the transmission. Drove it to the office from the dealer and still the same issue.

    Best way I can explain it is that when I slow down and the car downshifts, it's not very smooth. I can feel it slow down and then almost speed up (RPM also goes up and down) which makes it feel like its jerking. It is subtle but noticeable.

    Will update once I drive it more.
     
  8. upsidedown

    upsidedown Australia Active Member

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    Thanks musawi I'm looking forward to any updates you can give us on this problem. Mine does the same thing and even though I've tried to change my driving style I still can't get it to shift smoothly especially on the downshifts like this:

    and sometimes on the upshift as well like this:

    Seems to be the most jerky upshift in most cases is going from 4th to 5th
     
  9. musawi

    musawi Bahrain Newish Member

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    Driven it in multiple modes. Most noticeable in sport mode, but issue still persists in all other modes.

    I'm not sure how but the dealer wasn't convinced that there was an issue with the car even after driving it. It definitely bothers me, so I'm not sure what else to do now.

    My car was fine when I bought it, but a month and a half in, I noticed this. Similar experience?

    I will keep an eye out for this.
     
  10. Chris

    Chris United States Stinger Enthusiast

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    You all should check your transmission fluid level. Rumor is there is a tsb out about some transmission leak. If your low on fluid, that could affect your shifts.
     
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  11. musawi

    musawi Bahrain Newish Member

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    Just called them - they said they knew about the TSB when they had my car and it was fine.
     
  12. Chris

    Chris United States Stinger Enthusiast

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    But did they check the fluid level, or just look to see if it was leaking from that one spot the tsb mentioned. If it was me I would check it myself. Takes 2 minutes..
     
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  13. upsidedown

    upsidedown Australia Active Member

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    I can't really remember what mine was like straight after I bought it but I think it was similar to now. Now that I'm more used to the car over what I had previously (manual) I believe that I am noticing these type of issues more often
    I suspect that the dealers are going to say there is no problem because it is probably just how the car is programmed so not really a fault as such. I guess that if enough people bring this to Kia's attention there may be some sort of reprogamming fix available if that is where the problem lies. If it's the transmission then that will be an entirely different proposition.

    Anyway keep us updated
     
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  14. CrisX

    CrisX Canada Member

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    I also experience the jerky transmission shifting occasionally, mostly during the first half hour or so in cold weather. However, a more serious transmission problem surfaced recently. l will start a new thread. Potentially, it's a safety issue.
     
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  15. Marc Collins

    Marc Collins Canada Stinger Enthusiast

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    This issue came up years ago on a car I used to have--The Infiniti G37 with 7-speed transmission. Lots of identical discussions in forums back then.

    Question 1: do you have any evidence that the car actually speeds up when you are coasting and it is downshifting? Most of the inexperienced Infiniti folks mistook the rpms going up during each downshift as the car speeding up when clearly the higher rpms cause the car to slow more than it otherwise would if there was less aggressive downshifting.

    The whining and wailing about this eventually caused Infiniti to get rid of the sporty downshifting and reprogram the car to act more like a 1970's Buick. The original programming was aggressive in normal mode and really aggressive in sport mode. The reprogrammed car was barely any different from an economy car or luxury car in normal mode and the sport mode was so subtlety more aggressive many people couldn't even notice the difference.

    For the sake of those of us who prefer the transmission to be in the right gear at all times and prefer more aggressive downshifting, if you petition to have it made less aggressive, please ask for this in ECO and Comfort, but leave Sport alone :)
     
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  16. upsidedown

    upsidedown Australia Active Member

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    Well I'm pretty sure that when you have to press harder on the brake pedal, to have the car slow at the same rate it was before the downshift, then that is a sign that you have lost the same level of retardation that you previously had. Now I guess technically the car can't speed up if you are slowing down so I think that because the rate of slowing down is changing during the downshifts then it feels like it is speeding up.
    Hope that makes sense?
    Anyway however you want to describe it in my opinion if you constantly have to change the brake pedal pressure to adjust for the shifts then that is not right

    And yes agree that sport should always be sporty even if they change ECO and Comfort which in my opinion won't be a bad thing
     
    Last edited: Feb 26, 2018
  17. Jesse

    Jesse Canada Member

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    The downshifts are different feeling in this car. I've found that the gears do grab firmly if you just feather the brakes. In fact, I've found the car slows quite well without even using the brakes, and it has amazing stopping power when I want it.

    The issue for most of us was a very hard upshift with a cold engine.
     
  18. Marc Collins

    Marc Collins Canada Stinger Enthusiast

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    Well, I would say test without using brakes...the rate of deceleration will change as each new gear is engaged, but then at some point you might feel the torque converter unlock and it will go limp and feel more like an old-fashioned auto slushbox. Try in Sport versus Comfort because the behaviour will be different.

    If you have to modulate the brakes, then that would be caused by the auto-blipping of the throttle on downshifts that is designed to rev-match for smoother downshifting (less clunking). However, I have felt other cars where in an attempt to do this, there is actually a surge ahead of the downshift. It is mis-timed, so instead of happening in between the gears/during the shift, it pushes you forward just ahead of the shift. Highly annoying!! If this is happening, the transmission shift logic is at fault and needs to be reprogrammed, or you have a mechanical fault in your car's transmission if no one else gets this.
     
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  19. musawi

    musawi Bahrain Newish Member

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    Downshifting shouldn't be this aggressive in Smart, ECO or Comfort. It's definitely not comfortable. Definitely complaining when I take my car in. Hopefully they can re-program this again.

    Weird that I didn't notice this when I first got my car. Have a feeling they must have done something when I replaced my exhaust.
     
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  20. Marc Collins

    Marc Collins Canada Stinger Enthusiast

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    Disagree. I prefer the aggressive downshifting. Even the CVT in our new Impreza mimics this behaviour (in plain and definitely not sport D, not manual shift mode). It may be even more aggressive than the Stinger! Electric and hybrid cars work this way. Get used to it--if you don't want to slow down that much, don't take your foot off the accelerator completely. Removing your foot means maximum slow down, just as it would with a manual transmission.

    You can't simulate a manual transmission (what we all want in a sporty car) with 1970's Buick slushbox coasting/gliding.

    Question, though: do you experience the same level of downshift aggression in ECO, Comfort and Sport, or can you detect differences?
     
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