Hard downshift transmission

[Ohnosteveo]

So I noticed my 2018 GT1 was downshifting pretty hard, cruised the forums and saw the general consensus was to have the dealer Reset/replace the transmission control module. After a week of them diagnosing it they decided to put in a brand new transmission Anything have anything like this happen? Dealer even said they’ve never had to replace a stingers transmission but thats what they decided was the solve all.

 

[t2flair]

So I noticed my 2018 GT1 was downshifting pretty hard, cruised the forums and saw the general consensus was to have the dealer Reset/replace the transmission control module. After a week of them diagnosing it they decided to put in a brand new transmission Anything have anything like this happen? Dealer even said they’ve never had to replace a stingers transmission but thats what they decided was the solve all.

Just curious if you had any updates on this?

 

[MerlintheMad]

Do the transmission reflash TSB first! That is the "consensus", not replacing the whole trans. Good grief.

 

[ShannonC]

So I noticed my 2018 GT1 was downshifting pretty hard, cruised the forums and saw the general consensus was to have the dealer Reset/replace the transmission control module. After a week of them diagnosing it they decided to put in a brand new transmission Anything have anything like this happen? Dealer even said they’ve never had to replace a stingers transmission but thats what they decided was the solve all.

KIA has replaced at least two transmissions in AUS due to hard downshifts.

 

[Ohnosteveo]

Nevertheless they ended up replacing the transmission. but on the drive home it had a coolant leak which was steaming under the hood so i had to take it back. also noticed the dealer was nice enough to dent the rocker panels form the car being on the lift so they opted to replace those as well....its been a journey

 

[General_Vodka]

Nevertheless they ended up replacing the transmission. but on the drive home it had a coolant leak which was steaming under the hood so i had to take it back. also noticed the dealer was nice enough to dent the rocker panels form the car being on the lift so they opted to replace those as well....its been a journey

at least they admitted to the rocker damage.

 

[5tinger]

Just to be clear by hard shift do we mean clunky upshifts and downshift? Or something in the sense of excessive engine braking causing a jerking sensation?

 

[DoctorStiches]

I use manual mode and paddle shift alot so when my stinger is in auto (the tranny has learned how i drive) it does downshift early and upshift late annnnnd if you are not giving enough throttle at whatever rpm your at the car itself lurches or jolts you because the car was sure you would be going faster. Its a 'fast shift thing. And a 'learning softwear' thing. Tho i do not know how severely this affected you.

 

[SafetyPilotCal]

So here's yet another transmission being replaced for harsh downshifts. I already had the adaptive shifts reset once, and now the harsh downshifts have returned, except even worse than they were the first time.

 

[87and66]

Nevertheless they ended up replacing the transmission. but on the drive home it had a coolant leak which was steaming under the hood so i had to take it back. also noticed the dealer was nice enough to dent the rocker panels form the car being on the lift so they opted to replace those as well....its been a journey

sounds a lot like what happened to me. Had my trans replaced because of a leak. Then had a coolant leak after they replaced the trans and had to be towed back. Only to have it "fixed" and still leaking. Car still smells like coolant 2 months later.

 

[t2flair]

Just to be clear by hard shift do we mean clunky upshifts and downshift? Or something in the sense of excessive engine braking causing a jerking sensation?

I'm not OP but have been noticing similar issues. Sport mode is the worst, eco is the least noticeable. If I've been going along at let's say 50 mph, approaching a red light. I let off the gas, there will be a noticeable jerk / hard pump of the brake sensation when it downshifts (always around 25 mph) even without braking at all. The same will happen when it shifts down to first. If I maintain speed up to the red light and then brake harder later, the jerkiness is less noticeable. It happens every single time without fail. It does seem to slightly improve if the car is warmed up.

 

[5tinger]

I'm not OP but have been noticing similar issues. Sport mode is the worst, eco is the least noticeable. If I've been going along at let's say 50 mph, approaching a red light. I let off the gas, there will be a noticeable jerk / hard pump of the brake sensation when it downshifts (always around 25 mph) even without braking at all. The same will happen when it shifts down to first. If I maintain speed up to the red light and then brake harder later, the jerkiness is less noticeable. It happens every single time without fail. It does seem to slightly improve if the car is warmed up.

This is normal. It's basically downshifting to assist with braking and when you want to accelerate the transmission will be on the right gear so response is better.

I guess it would take some getting used to if your coming from old coasting autos.

 

[G70 Owner]

I'm not OP but have been noticing similar issues. Sport mode is the worst, eco is the least noticeable. If I've been going along at let's say 50 mph, approaching a red light. I let off the gas, there will be a noticeable jerk / hard pump of the brake sensation when it downshifts (always around 25 mph) even without braking at all. The same will happen when it shifts down to first. If I maintain speed up to the red light and then brake harder later, the jerkiness is less noticeable. It happens every single time without fail. It does seem to slightly improve if the car is warmed up.

this is not normal, a trans adaptives reflash will fix it for you

 

[SafetyPilotCal]

It is not normal. At this point I've driven probably dozens of modern 8, 9, and 10 speed automatics, including other non-Stinger/G70 Kia/Hyundai products with the A8TR1 I have never experienced anything as jerky as this. It feels like someone can't drive a manual and is just dumping the clutch into the next lower gear. The fact that this problem didn't start until 7-8K miles into the ownership AND that the adaptive shift reset fixes it proves it's not normal. It's either a defect in the transmission itself or something very wrong with how the TCU logic in the Stinger and G70 learns shift quality.

 

[MerlintheMad]

In all likelihood it is normal; the actual sensation does not translate in text. Sport, as described, is more noticeable: and that is even a description in the manual: everything about acceleration and deceleration in Sport is more abrupt, even (some might say) "harsh". But, if it bothers you, take it in and take a tech for a ride, even let them drive it to see for themselves: maybe the dealership will let you compare with a test drive of another Stinger, if you're not convinced.

 

[SafetyPilotCal]

Slamming into the next lower gear in Comfort mode is not "normal". It isn't sporty, it isn't like more performance oriented cars I've driven, it's garbage.

 

[MerlintheMad]

Slamming into the next lower gear in Comfort mode is not "normal". It isn't sporty, it isn't like more performance oriented cars I've driven, it's garbage.

"Slamming lower" in Comfort is definitely not normal: so, take them for a drive, and then go together in another Stinger: should be obvious if "slamming lower" is in your car and not another Stinger: at which point you have agreement and can move forward: starting with the transmission logic "reflash".

 

[SafetyPilotCal]

This now the second time the dealer has "investigated" the issue, I will report back on what they find when I take the car there week after next (earliest they could get me in and give me a loaner).

There is no TSB reflash for any shift-by-wire Stinger, and nothing past the 2018 model year. There is no reflash or recalibration available for 2019+ cars. You're referring to TSB SA341, which is only for shift-by-cable 2018 Stingers. That reflash corrects a very specific condition with first gear engagement during abrupt shifts from Park to Drive.

I had to run some errands earlier and I drove the car in Sport mode the entire time, where the downshifts are actually better than in Comfort mode. I guess it's possible there are separate shift adapt tables for the various drive modes and the car hasn't figured out how to make the Sport downshifts terrible yet (I rarely ever drive in Sport).

 

[MerlintheMad]

There is no TSB reflash for any shift-by-wire Stinger, and nothing past the 2018 model year. There is no reflash or recalibration available for 2019+ cars. You're referring to TSB SA341, which is only for shift-by-cable 2018 Stingers. That reflash corrects a very specific condition with first gear engagement during abrupt shifts from Park to Drive.

Aha, you've actually researched this, by the sound of it: I've been repeating what I read on here, which is problematic. Interesting theory: you're of the belief that the system "learns" a driving style: and in each of the driving modes: I'm unconvinced. At best, Smart mode would memorize some consistency and adjust shifting points accordingly: the manual (at least for the 2018 model) only talks about that adaptive adjustment when describing Smart mode.

So, your eliminating of the TSB "reflash" would leave, what, as possible issues going on to produce harsh shifting points?

 

[SafetyPilotCal]

Adaptive shift tables don't really learn your driving style, they learn the line pressures and shift times required to make the transmission shift the way the logic thinks is most "correct". This is how it works in GM PCMs and I assume Kia's implementation of it is likely very similar. You can think of them as similar to LTFTs and STFTs, where the car learns how much fuel to add or remove for a given RPM+MAP+whatever.

I don't know the secret sauce behind Kia's transmission control logic, and if anyone does they're generally vendors being quiet about it. I do know that transmissions must be "paired" with the car when replaced. Per KGIS, this is specifically called "Oil Pressure Characteristics input" and requires either scanning a 2D barcode or manually inputting numbers off the side of the case. So it sounds like the TCU could be expecting a wide variety of ranges and tolerances related to the line pressure of the transmission. Why this is the case, I have no idea. I've never seen it on another car. If the TCM truly is determining line pressure based off those random values printed on the side of the trans case, and those numbers are wrong (edit: in some cases), that could certainly cause the problem people like myself are reporting.

That's just a hypothesis, though.