Kia Optima 2.4 2018 - 6sp AT Shift flare when cold - first shift of day

I was getting this shift flare on the first 1-2 sometimes 2-3 with medium throttle and the first shift of day. Only happened when car sat for a while and temps were 50~F and doesn't happen all the time.

I changed the fluid with Valvoline Maxlife ATF. I thought if I changed the fluid, it would go away. The fluid was pretty dirty for only 30k so I'm glad i did. Around 4qt came out and I put in at least 4.5qt (spillage). Also, the car was already somewhat warm as I had to drive to my parents to use the jack (live in apt). I did the level set at proper temp, etc so I'm pretty sure its not a fluid level issue.

Car only has 30k, so I'm wondering if this is normal operation due to "warm up" or engine running rich. It doesn't happen on light throttle. Anyway, I plan to do another D&F this weekend with around 5 liters. When the car warms up it shifts like a dream, even better than before. Only thing I can think of is the car was underfilled from the factory, and I should've put in a little more. The shop manual calls for 5 liters on a refill then level set.

Looking for insights here. Thanks.
Try a 10oz bottle of lubegard red
After 500kms this will eliminate your shift flare.
We had a 12 santa fe and just bought a 19 santa fe.
Both had the issues you are experiencing.
Libegard and a drain and fill of maxlife aft. Issue fixed in both Hyundai's.
 
Drove 500 miles to Las Vegas, and a 7 hour bumper to bumper drive back. :mad:

No issues to report here. Car shifted great, no flare and pretty smooth given the traffic. Glad I got 2 d&f with full syn in before that traffic.

Definitely put in at least 5 qts with these kia 6sp AT.
 
The flare happened today being 59 degrees, but only from 2-3 under moderate acceleration. I read somewhere else this may be an emissions thing due to the computer wanting to warm up the cat or advancing timing; something along those lines. It definitely seems like a glitch. I idled for maybe 15 seconds but didnt just sit there for a minute. I literally drove to the end of my block the flare occured from 2-3, and never again. It almost seems the engine wants to rev more than upshift.

If generally speaking 2-3 quarts stays in the torque converter theres no way this can be underfilled because I put in just under 5.5 quarts. I don't want to take this to Kia because this will be impossible to reproduce and theyre not really helpful with anything. After that first shift everything is butter. I might try the lubegard Red next time I do a d&f but I am sick of getting under the car and dealing with the 3 part splash guard.
 
count me interested as girlfriends preowned 18 optima is said 6 spd. shorter warranty being preowned. a great car so far with only DIY oil changes, but was figuring a tranny F+S in the near future with 30 some thou on it. while looking on the kia optima forum i see the procedure that used to be available + thought there was a way to check the fluid level + seen several times trannies were underfilled a bit as even 4 oz times thousands of trannies = $$$$$
 
I have a funny feeling this trans was a half quart low. I just went through the hyundai level check again with another quart of ATF. This time I used an amazon purchased BAFX android BT OBD2 scanner with Car Scanner Pro. This app pulls ATF temps and as a bonus allows you to reset AT adaptive learning.

Prior to performing this procedure I monitored ATF temps in general. One thing I noticed is its almost impossible to get the temps to the adjustment range from HOT in a reasonable amount of time. I'm pretty sure this was the problem, since I was driving my car to my parents to do the ATF change. When fully warmed up, temps are around 195. I believe it was a mistake to do this after warming the car up. I found a nice spot on the street the night before where I did my work at 7am Sunday.

I put in 750ml into the stone cold ATF case, drove up ramps, removed all the underbody crap. Drove around the block and waited for the temps to hit 130. Did the P-R-N-D with 3-5 second pause at each gear twice. When I pulled the level check on steady ground, there was an inital burst indicating it was overfilled at the level - but after a 1-2 seconds it steadied to a normal stream. No more than about 5-10 ounces came out. I drove the car around and havent noticed any shift flare but we'll see. The car does seem to shift smoother from cold. 2017-2018 model year Sorrento's had ECU update to resolve 2-3 shift flare, so maybe they will eventually put one out for the kia's.
 
Fluid level check on my 6-speed Hyundai/Kia is 122F-140F

What I do is fill her up, get the ATF to ~115F, open the fill level check overflow plug, and then close it at 122F. Don't wait or check at 130F-135F.
Obviously, vehicle is parked on a level enough surface, kept running, and cycled thru all shifter locations.

Since the car is drive by wire, transmission issues can be any part of the drivetrain. Toss in a bottle of quality PEA based FI cleaner, run an IVD/port cleaner, clean the throttle body, inspect the spark plugs, replace an old air filter, ...

With the warranty on Hyundai/Kia's, if issue occurs, I would leave vehicle overnight at dealer, and go for the test drive with the tech in the morning.
Just picked up a new 6-speed Kia and no cold start morning shift flare, nor did the 2011, 2014, or 2016.
 
Fluid level check on my 6-speed Hyundai/Kia is 122F-140F

What I do is fill her up, get the ATF to ~115F, open the fill level check overflow plug, and then close it at 122F. Don't wait or check at 130F-135F.
Obviously, vehicle is parked on a level enough surface, kept running, and cycled thru all shifter locations.

Since the car is drive by wire, transmission issues can be any part of the drivetrain. Toss in a bottle of quality PEA based FI cleaner, run an IVD/port cleaner, clean the throttle body, inspect the spark plugs, replace an old air filter, ...

With the warranty on Hyundai/Kia's, if issue occurs, I would leave vehicle overnight at dealer, and go for the test drive with the tech in the morning.
Just picked up a new 6-speed Kia and no cold start morning shift flare, nor did the 2011, 2014, or 2016.
Thanks for your reply. In the attached transmission fluid replacement guide for kia/hyundai, they do mention to check closer to 122. Now that I have a scan tool there is no question on the temps. I started the car today stone cold and drove around. Gear changes 1-2-3 are firm when cold, but no shift flare whatsoever. Actually it seems it shifts faster when cold. I can only surmise that the level was slightly below spec because I didn't get the flare consistently when cold, and it only occured from when the car had sat overnight and trans fluid temps were equivalent to ambient. The annoying thing is this flare occured on factory fluid as well, which means to me the car was similarly underfilled from the factory.
First d&f: Out 4.5qt, In 4.5qt (shouldve put in more, probably less than 4.5qt since I spilled alot)
Second d&f: out 4.5 qt In 5.5qt
Level check +750ml

If I knew what I know now I'd do a level check first before draining anything. The only good part is the fluid that came out was very fresh looking. I'm officially done with this transmission for the next 3-4 years, the underpanels are too much of a pain.
 

Attachments

  • SB-10076424-5448.pdf
    302.4 KB · Views: 33
@haggler
Have you ever tried to extract the ATF through the fill hole?

I tried it with my other car and I can get at least 2.5 qt. (or more?) out but that car has a dipstick for ATF. I stopped about 2.5 qt because that's how much fresh atf I had at home. Haven't tried again so not sure how much more over 2.5 qt I can extract.

Looking at your attachment pictures (post abive) seems like the atf container is not that big. Curious if it holds enough atf to use a vacuum extractor. I want to try it on our 2014 Tuscon this time. Last time I drained it.
 
@haggler
Have you ever tried to extract the ATF through the fill hole?

I tried it with my other car and I can get at least 2.5 qt. (or more?) out but that car has a dipstick for ATF. I stopped about 2.5 qt because that's how much fresh atf I had at home. Haven't tried again so not sure how much more over 2.5 qt I can extract.

Looking at your attachment pictures (post abive) seems like the atf container is not that big. Curious if it holds enough atf to use a vacuum extractor. I want to try it on our 2014 Tuscon this time. Last time I drained it.
Im not sure I thought I read somewhere it doesn't go straight down (can't put an aftermarket dipstick), so maybe vacuum would work but I don't know if there would be ramifications of doing that. Especially with high mileage. On the SUVs the under body panel is way easier to take off because it's one piece, at least thats what I've seen with the Sorento. I would not attempt this unless the vehicle is cold and you have an obd2 with trans temps. Drain and fill is really easy and easy to get the level correct if you have the right tools. I wish I did the first few time, I could have done a few d&f only taking off the covers once. The covers on the optima are a nightmare.
 
I took my car out for a long drive. The car never shifted this smooth warmed up, even before or after the first drain and fill. And keep in mind this car only has around 28k. This leads me to believe either the fluid was still substantially dirty or the atf was underfilled, probably the latter.
Our 2019 santa fe was underfilled .5 quarts from the factory......so I'm not surprised that yours was also.
 
Since this thread is revived, what is shift flare? What does it feel like?
Its when there's a delay in engagement between gear but the engine revs. Almost as if it stops in neutral, revs, and then the gear hits a second or two later.

No issues with max life 3k later. Engagement is firm when cold but quick. Shifts very smoothly when warm. Glad I didnt blow my money on the OEM fluid.
 
I wanted to update this thread from a recent fix that corrected the flare, as well as some bucking when shifting from 2-1 coming to a light

This bulletin provides the procedure to improve the gear shift logic of the Transmission Control Unit (TCU) on some 2018MY Optima (JF, JFa) vehicles produced from April 18, 2017 through July 11, 2018, equipped with 2.0L T-GDI and 2.4L GDI engines, which may harsh downshifts (including 2-1 gear change).

I had the dealer do the TCU update and I no longer get the flare when cold. There is a similar TSB for earlier year Optima's as well as some other SUV's. It was well worth the half day I wasted at the dealership 😫
 
You know whats funny, is i use Maxlife in the Elantra, (3X3 method) and i also get a super slight 2-3 flare, and a firm downshift, 3-2 when cold and first shift of the day. Only once, and never again for the whole day.. I dismissed it, because it never got worse, if anything is getting better with time lol. It does not feel mechanical, its more like the computer is not adjusting correctly or pulling the timing during a 2-3 shift when cold..

On the Sonata with the 6 speed automatic, i used OEM fluid type SP4-M i believe, did a drain and fill, plus cleaned the magnet on the drain plug. It never had any issues, but after about 45K miles it was shifting i thought slightly "sloppy", non direct, no flare during shifting, but just slow-ish. I drained the old fluid via the bottom drain bolt, and refilled via the top fluid add port - it took like 1/2 hour to add the fluid via this method. Looking back i would i added the fluid via the inspection port. Checked when warm-ish, and the results were amazing!.. It literally shifted like brand new. It also engages the gears faster and so smooth you can not feel it shift, such as D to R or R to D. I will change fluid every 30K for here on out.. Its good to hear a software update fixed your flare! Our Sonata already had all dealer software updates, (knock sensor update also) when i picked it up with 2K miles on it in 2018, i recently called the dealer again, still current software as of late 2021.

IMG_1978.jpeg
IMG_1979.jpeg
 

Attachments

  • IMG_1980.jpeg
    IMG_1980.jpeg
    52.4 KB · Views: 6
Last edited:
Yeah, I think programming is the biggest difference in these transmissions. The 6 speed autos are all the same between Hyundai and Kia. I don't have any flare issues, but it's certainly not a smooth trans when cold. I've had two D&Fs done on mine, the first with OEM fluid and the second with Amsoil. I'll do a third here in about 10k or so miles, again with Amsoil. Overall, these are solid units and shouldn't have many issues throughout the life of the vehicle. Even neglected, these transmissions last quite some time.
 
Ya it overall smoothed out the tranny. Like for example on low throttle where it wants to shift at low RPM, it will rev it out another 100-150 rpm before the shift so it engages smoother. The car wanted to buck when slowing gently to a stop sign shifting to 1 (like a car with old fluid). That was resolved too. I knew it was a computer thing because this didn't happen in manual mode even when stone cold, just slower shift.
 
Last edited:
With the car having just 30k and 4 years you should have just recorded that with no noise so the engine can be heard and the rev needle being harsh and ask for a warranty claim while also letting them replicate the issue themselves instead of jumping the gun. if they see the fluid was clearly replaced very recently once they go to inspect it they'll just blame that.

If you'd have gone to get it warrantied without touching it and they tried to get you to pay for a fluid change just say it hasn't met its interval or there isnt any so you shouldn't be forced to pay any to fix an issue since there is no mention of it in the manual. You never give the dealer leeway on making you pay when you don't have to. But neither do you give them leeway in a claim denial since you did something yourself before going to them.

But now since you changed the fluid and didn't use the exact dealer one they will blame your oil choice and the way you did it and will probably not budge even if it was before the fluid change. I hope you resolve that without trouble.
 
The problem I had with the car was resolved with a TCU reflash per that TSB issued in 2/2020. Trying to get the dealer to replicate would be near impossiblen since the flare only occurered on the first few shifts of the day. And the kia dealerships are horrible. While the TSB doesn't mention shift flared, it fixed the issue. This is the reason for my posting and resurrecting the thread.
 
Back
Top