I have a 2016 Hyundai Sonata 2.4L with 125,000Kms on it. Car shifts very smoothly when moving forward but usually while slowing down it jerks (sometimes quite a hard jerk) when it downshifts. Most of the time it does so from 3rd to 2nd gear.
I bought it used a month ago when it had around 121,000KMs on it. Didn't notice the jerk when test driving it. Immediately after buying it, I took it to a mechanic to have the transmission fluid checked and he recommended to change it so I agreed. Only 4 liters in the pan was changed, we didn't flush it.
Now I am not sure if the fluid change is what caused it because I didn't notice it before but then again, I had only driven it for around 50-60KMs before changing the fluid. Note that the jerk doesn't happen all the time. It happens occasionally. Sometimes it's not too hard, sometimes it's so hard it feels like the car applied brake on its own.
What could be the problem? Any help is appreciated it. Thanks.
Have you ever serviced the tranny?
Hyundai-Kia 6 speed transmissions are pretty bulletproof - usually all failures occur due to lack of maintenance.
Take out the transmission dipstick (it’s a 2016 so it has one) and inspect the condition of the fluid - is it fully dark? Does it have chunks in it?
What you can do is perform the TCM reset procedure and adaptive leaning - it usually clears out those issues.
It’s simple:
- reach ATF op temp
- park
- put parking brake on
- go from N to D and back 5 times, each time pause for ~5 seconds in each position.
- disengage the park brake and go for a drive
(you know when you done it right by the tranny shifting like crap after the reset)
- accelerate with very low throttle (~15%, so almost not touching it) through all gears
- decelerate with no throttle through all gears
- repeat the acceleration and deceleration a few times, you can stop in between. Do it until it’s 100% smooth.
- drive normally for a bit
- drive with more accelerator pressure than usual
- park and turn off the car
- Process complete.
Do at your own risk, if the tranny has been neglected - this may not help but instead make things worse.
generally you can slightly feel Hyundai-Kia transmissions downshift, and that’s normal for any brand - but it definitely shouldn’t be excessive.
“another junky transmission”
it’s worth adding that Hyundai-Kia 6 speed conventional automatic transmissions are some of the best in the business.
They have by far the best amount of diagnostic pressure ports, part availability, and mainly fail due to neglect.
Scotty himself said that he has never seen one outright fail.
I bought it last month when it had 120k Km on it. There is no servicing history so my guess is it hadn't been serviced before.
The only service I did to it was that I got the fluid changed right after I purchased it. The fluid was kinda dark but I didn't notice any chunks in it.
I will do the TCM reset and see if that fixes anything. Thanks.
What could be the problem?
The problem, unfortuantely, is that you bought a Hyundai. They just make really junky engines and transmissions.
:((
Yeah I suppose you're right but what's done is done. I really like everything else about the car apart from this one issue. I hope it's an easy and not too costly fix.
hate to burst your bubble, but most of a transmission's moving parts are under an inch of aluminum, and bolted up deep in the core of your car. the "fix" is usually to pull it out and then put a different one back in. A huge expensive job.
And in this case, you would be replacing with ... another junky transmission.
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