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Discussion Starter #1
Hi All,

I read some threads for harsh downshift for older Sonata models and looks like I am experiencing the same. It became to the point where it pisses me off and also makes my wife sick when she drives with me. They issue I experience seems to happen only on fully warmed up engine. Lets say I am about to slow down and I let the car slow down itself without engaging break pedal. At the point when transmission downshifts from 3rd to 2nd gear, I hear clunk in the engine/transmission and car slows down like I downshifted it from 5th gear to the 1st. It is worst when I have my break pedal slightly engaged because it really feels like I slam breaks when the transmission downshifts from 3rd to 2nd gear. I was stuck in the traffic on the highway today and it would do it multiple times. My wife looked at me asking what am I doing and I keep telling her the car does that and I cannot control it. It also becomes a safety issue for me as the car behind was keeping not enough distance and this could end up in someone rear ending me when this happens. I would love to bring it up at the dealership but I have bad experience with Hyundai service departments. I used to have 2013 Azera with warm engine startup rattle and it took many visits/videos and documentations before they finally replaced my engine.

Any input/suggestions are much appreciated.

2018 Sonata Limited + Ultimate Pkg and 16k miles on the clock.

Thank you,
PK
 

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You can check on the following Website to see if there are any open campaigns for your VIN.

https://autoservice.hyundaiusa.com/campaignhome
have your VIN handy The search will let you know about recalls and campaigns. Campaigns include software updates, that could correct your issue. If that does not work, see your Dealer, schedule a time they can ride with your with the car warmed up..

Good luck
 

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2017 Sonata Sport 2.0T
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Your 2018 has the new 8 sp transmission, first year so it does not relate to any of the older Sonata 6 sp transmissions. IMO your only smart option is get to the dealer and make them ride with you to show the problem ans get it documented.

it may just be something as simple as a software update. But there is nowhere else you have as an option for your warranty work
 

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Discussion Starter #4
Thank you for your input. Mine is 6 speed. I think only the eco and 2.0T gets 8 speed. I guess I will schedule an appointment with someone that I will be able to take for a spin because I know if I have them go on their own they will not find anything. I know that there are not too many 2018 owners out here yet but I hope this thread will come in handy to someone experiencing the same. I will keep this post updated.
 

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What car were you driving before the Sonata?
Your Sonata transmission, like most of them out there today, does not have any one-way clutches above 2nd gear to smooth out upshift/downshift steps. Back in the old days, transmissions had these sprag or roller clutches that transmit power in one direction and freewheel in the other direction, like the hub of a bicycle that lets you pedal ahead and then stop pedaling and the wheel continues to spin freely.

What gives the downshift such a thump is that the computer is locking the engine to the transaxle by commanding full lockup of the torque converter, and then turning off the fuel injectors. With the engine locked to the drive axle, the car's momentum spins the engine but it doesn't burn any gas. If you press the accelerator very very lightly, you will feel a sort of skip/hiccup as the injectors switch back on. There is no way to disable this fuel-saving trick and most of not all modern cars use the same technique. In extreme cases, such as a passenger with spine or neck injuries that make this sort of surge very painful, you can move the shift lever to N until the speed is below 15mph and then move it back to D. Neutral breaks the connection between the engine and wheels, and forces the engine to burn gas and idle. You can move the lever back and forth between N and D at any speed as long as you're foot is off the accelerator when you do it.
 

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You can check on the following Website to see if there are any open campaigns for your VIN.

https://autoservice.hyundaiusa.com/campaignhome
have your VIN handy The search will let you know about recalls and campaigns. Campaigns include software updates, that could correct your issue. If that does not work, see your Dealer, schedule a time they can ride with your with the car warmed up..

Good luck
Use that website with a grain of salt though. Its wrong for both my 2015 Sonata and my 2017. Only the 2015 is showing 3 completed recalls and 0 open while there should be several more of both. My 2017 is showing 0 of either and I know the dealer has done a few already.
 

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Discussion Starter #7
Thank you dmlexpert for explanation. I would understand it if every downshift from 3rd to 2nd gear was harsh and noticable even by a passenger but it is harsh randomly. All other downshifts are smooth as butter. My previous cars in order from latest to oldest:
2013 Hyundai Azera Tech
2007 Audi A6 V8 4.2FSI
2007 Acura TL Nav
2001 Audi A8L
1996 Audi A6
1989 Nissan Maxima

Only car with harsh downshift was Acura but this could have been easily fixed by replacing gear switch(common Acura TL thing).
 

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I am curious if this harsh downshift 3==>2 is the same in all driving modes "Sport, Eco, Normal"? I will pay more attention to my 2017 SE to see if it exhibits any similar issue.

Frank 2017 Sonata SE
 

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Thank you dmlexpert for explanation. I would understand it if every downshift from 3rd to 2nd gear was harsh and noticable even by a passenger but it is harsh randomly. All other downshifts are smooth as butter. My previous cars in order from latest to oldest:
2013 Hyundai Azera Tech
2007 Audi A6 V8 4.2FSI
2007 Acura TL Nav
2001 Audi A8L
1996 Audi A6
1989 Nissan Maxima

Only car with harsh downshift was Acura but this could have been easily fixed by replacing gear switch(common Acura TL thing).
The '13 Azera uses the same basic transaxle while the earlier cars are entirely different. With the gearing of the Sonata, 4-5-6 are closely spaced while 1-2-3 are fairly far apart. The converter stays locked as long as possible on the downshift, and fuel cut is active until just under 20mph. The Azera drops out of fuel cut at higher speed, before the bumpy downshift.
The Audi/Acura/Nissan used different transmissions and different engine calibrations so you wouldn't have felt the same thing in those cars.

You're saying it's random, but is it happening consistently during certain coasting stretches in a daily commute, or is it more random than that?

Try changing the Eco/Sport setting from your current selection to the other one and see if the behavior changes. What I'd look for is some sort of consistency, meaning finding the combination of variables that make it more likely to happen.

It doesn't sound like it's "broken" - meaning the dealer would likely tell you "no problem found". But if you can find a set of conditions under which you can make it misbehave, you can demonstrate it to the dealer and then explain that if it were normal behavior, it would (or should) happen all the time and not when certain seemingly random tumblers click into place.

My wife's '17 Limited has the same transaxle and it doesn't have the 3-2 bumpshift, or even a 4-3 bump. It does occasionally exhibit the hard 1-2 bump on the first shift on a cold morning. That is a characteristic of these newer designs, combined with very cold fluid.
 

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Discussion Starter #10
Thank you! It happens every single time when I come back home, there is a very small incline and I usually let the car slow down on its own and it always does that. The thump/clunk sound and feel is strong and makes you feel like something just broke down every time it does that. I haven't tried other modes yet. I started to notice this behavior when car had approximately 8 - 9k miles on it. I will see if I can record it today and share video.
 

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I have a 2.4L 18" and I get the harsh downshifts randomly too. I thought It was my custom intake at first but I remembered that I've seen posts about this issue beforehand. Might take the intake off, pop on the OEM, and have it checked at the dealer.
 
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I have the same problem with my 2016 2.0t Ultimate. Happens around 55km per hour and the downshift is abrupt and a little jarring. I’ve also had passengers comment and had to explain its the car’s fault and not the drivers! Anyway through testing I can confirm the issue occurs in Normal and Eco modes, but is not present in Sport mode.

I don’t recall this problem when I first purchased the car and can’t figure out when it became so noticeable. I know that the car had a recall last summer and as a result had a computer update, might have been around then that this problem started. I plan to raise this issue at my next service appointment nonetheless.
 

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I have the same car and same issue, I drive about 100 miles a day for work and it happens maybe 25% if the time I’m driving , especially at the end of the day.


Sent from my iPhone using Tapatalk
 

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I have a 2018 Sonata Limited 2.0T and notice no harsh shifts with it! My only complaint is that the TREBLE control doesn't work on the INFINITY radio! The slider works, but there is no change in sound! The dealer tells me there is an update for the radio. I will my an appointment to have it done.
 

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I have a 2018 SEL and have experienced the harsh shifts as well. I have also had an issue where the car feels like its losing power when sitting a red light with brake pedal pushed. then when i take off there is a slight hesitation. I only have 2k miles currently too... :frown:
 

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Having the same problem...

Hi All,

I am having the same problem with my 2018 Sonata Sport and I am able to reproduce the problem consistently in Comfort and Eco modes. The problem is not apparent in Sport mode.

I am able to reproduce the problem by letting off the accelerator or braking at 15mph and as soon as the vehicle hits 14mph I feel like I got tapped by a car behind me. There is also a noise at the same time. This problem is not apparent in Sport mode.

I remember driving the car a lot in Sport mode when I first got it and did not notice this problem right away.

I am also having passengers notice this behavior. I am worried the transmission will fail early and that I will be rear ended as its like I am applying the brake:frown:. This is especially dangerous and annoying in tight traffic.

What should I do? Make an appointment with service?

Thank you.
 

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Hi All,

I am having the same problem with my 2018 Sonata Sport and I am able to reproduce the problem consistently in Comfort and Eco modes. The problem is not apparent in Sport mode.

I am able to reproduce the problem by letting off the accelerator or braking at 15mph and as soon as the vehicle hits 14mph I feel like I got tapped by a car behind me. There is also a noise at the same time. This problem is not apparent in Sport mode.

I remember driving the car a lot in Sport mode when I first got it and did not notice this problem right away.

I am also having passengers notice this behavior. I am worried the transmission will fail early and that I will be rear ended as its like I am applying the brake:frown:. This is especially dangerous and annoying in tight traffic.

What should I do? Make an appointment with service?

Thank you.
When I have scheduled appointment 2 months ago and complained about "feet dragging at low speeds before car stops" - like you approach a red light without pressing brakes - guy asked me whether emergency light went off. Once I did not have any lights and technician did not find any codes, they returned the car back with note: car is in specs, shows hesitation on low speeds which is normal.

If you do not expect any codes from computer, do not go to dealership.
 

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Same problem 2018 sonata slowing down a prompt downshift dealersaid they updated the computer but they're going to take it for a ride and see what's going on this is the second time I took it to the dealer and they supposedly updated the computer
 
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