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Discussion Starter · #1 ·
I've had this problem happen a few times in the last few weeks. When starting to accelerate from a complete stop, the car appears to be stuck in 1st or 2nd gear as I can hear it reving more than normal. At that point the car will make a loud slam or thunk sound and it shoots forward. It almost feels and sounds like I just got rear ended. The loud sound occurs when it finally shifts to the next gear.
Has anyone experienced this?
 

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I've had this problem happen a few times in the last few weeks. When starting to accelerate from a complete stop, the car appears to be stuck in 1st or 2nd gear as I can hear it reving more than normal. At that point the car will make a loud slam or thunk sound and it shoots forward. It almost feels and sounds like I just got rear ended. The loud sound occurs when it finally shifts to the next gear.
Has anyone experienced this?
Have you had any reprograms to the ECU yet? There's a multi ECU update that should help, or you have a real trans issue.
 

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i've had this problem happen a few times in the last few weeks. When starting to accelerate from a complete stop, the car appears to be stuck in 1st or 2nd gear as i can hear it reving more than normal. At that point the car will make a loud slam or thunk sound and it shoots forward. It almost feels and sounds like i just got rear ended. The loud sound occurs when it finally shifts to the next gear.
Has anyone experienced this?
 

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That isn't normal. Stop driving it and take it to the dealer. I know the auto transmission sucks but if it's not shifting as it normally would I wouldn't want to do anymore damage by driving it.

Does this happen at cold temperatures or while engine is cold? If so I know that the Multi ECU update fixes cold performance. I never experienced it since before and after the update (Miami, FL here). However it might fix your problem if it goes away after heat up.

Keep us posted.
 

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I have had this, search my older posts, there is also a link to a youtube video of mine having similar issues. It gets progressively worse. My transmission was replaced. I no longer have that issue but despite having the ECU upgraded several times, I've never been able to get the transmission to act as it did after the latest (version 2) ECU update before the transmission swap.
Please keep us updated on this, I hope it isn't going to start happening with more sonata hybrids... I seem to have picked up every issue possible on this car....
 

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Discussion Starter · #6 ·
Have you had any reprograms to the ECU yet? There's a multi ECU update that should help, or you have a real trans issue.
I performed the ECU upgrade in the summer to address the sluggish acceleration and it performed like a different car (improved performance). I'll have to take it to the dealer but not looking forward to it since it doesn't always happen and may take several drives for them to see the problem. I've never had a vehicle do this in my life.

Sent from AutoGuide.com Free App
 

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My transmission is incredibly smooth now since the update, even in the below zero temperatures we had in the past week. Drives like a whole new car. Sounds like your transmission may need work or replacement like Reglee's.
Best of luck.
 

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Sometimes that happens to me but not quite that pronounced. It seems to happen when it is changing from battery to gas power. I first noticed the clunk when I was sitting in the car waiting for my wife and it switched from battery power to gas.
The other day I was leaving the car wash there was a loud clunk when i accelerated pretty hard to get out on the highway. It had changed from battery to gas. In normal driving I never notice when it changes.
 

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Discussion Starter · #10 ·
Reviving my old thread as I've continued to intermittently experience this issue. I've brought the car to the dealership several times and they have not been able to reproduce the problem. I'm not surprised as I can't reproduce it either since it happens so infrequently. It does seem to occur more during colder weather months.
 

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Reviving my old thread as I've continued to intermittently experience this issue. I've brought the car to the dealership several times and they have not been able to reproduce the problem. I'm not surprised as I can't reproduce it either since it happens so infrequently. It does seem to occur more during colder weather months.
That's got to be incredibly frustrating.
 

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I would recommend doing a switch over to Amsoil Signature Series transmission fluid, as it flows better in cold weather.


AMSOIL Signature Series Fuel-Efficient Synthetic Automatic Transmission Fluid


Cold-Temperature Fluidity
Cold, thick automatic transmission fluid lengthens shift times and
reduces fuel economy. Signature Series Synthetic ATF is wax-free
and delivers extraordinary cold-flow properties (< -60°F pour point).
It helps improve shift response, energy efficiency and warm-up
times.
 

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No one has asked yet, so here goes. Your stick shift is never flipped onto the left side of the column, I suppose. Because if it was, you would have the same symptoms. Not shifting from 1st to 2nd.
In other words your leaving the tranny in manual mode.
 

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Discussion Starter · #14 ·
No one has asked yet, so here goes. Your stick shift is never flipped onto the left side of the column, I suppose. Because if it was, you would have the same symptoms. Not shifting from 1st to 2nd.
In other words your leaving the tranny in manual mode.
Definitely not the issue, just regular driving in the 'D' position.
 

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My first Winter, I found my 2014 shifted really hard during the first few sub zero transitions from EV to ICE.

I've learned to play with the throttle to "finesse" the transitions for first little while until everything warms up.

Your issue may be something completely different but cold affects this car like no other car I've owned.
 

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I think sometimes the car gets a little stupid. On my 2015 HSH LTD I find every once in a while the engine is running when just coasting on flat grade with the battery at 75%. I just slap it into neutral for a second and back into Drive and then all is well.
 

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Just as a reminder, take a look at this video, it led to a full transmission replacement. If it only happens when cold, I wouldn't worry about it so much. If it happens when car is warm and even at higher speeds, I think it's only a matter of time. One dealer wouldn't do anything about it even with the video because they couldn't replicate the problem in their short test drives. Find a different dealer...

https://www.youtube.com/watch?v=Of8fQdo-SAI

BTW, I've since traded in my 2011 and have a 2015. However, after replacement I drove for about another 50k before I traded it in and didn't have any issues.
 
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