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Discussion Starter · #1 ·
My transmission is having issues switching from 1st to 2nd gear and same issue from 5th to 6th. What happens, (when attempting to switch from 1st to 2nd) RPMs rev up high (as though it is in Neutral) then after 2-3 sec it shifts, car jumps crazy and in like 1 sec it shifts down (to 1st - RPMs jump) then shifts to 2nd gear and from there it is fine. 3rd to 4th, to 5th is great, but 5th to 6th same issue, not as extreme, but similar. If i let go of gas when it should shift to 2nd gear, and wait like 2 sec, it will be in 2nd gear without jerking - Normal. Sometimes in Park there is this noise as though something metal is hitting another metal part, and I can feel it in car - but it goes away and only happens from time to time. Also Neutral on rare occasion works as Reverse - super rare. I did Stall test (per Hyundai procedure Bulletin 13-AT-007) - no issues. Dealer ran diagnostic - no Codes in transmission. Flushed fluid - didn't help. I drained fluid again, put new fluid in and checked ATF level per 13-AT-006 - no difference. Tested Solenoids - no problem there. What could be an issue with my transmission?? 2012 Sonata GLS 2.4L with 7k miles.
 

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Did they reset the adaptive values? (clear its memory)
 

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My transmission is having issues switching from 1st to 2nd gear and same issue from 5th to 6th. What happens, (when attempting to switch from 1st to 2nd) RPMs rev up high (as though it is in Neutral) then after 2-3 sec it shifts, car jumps crazy and in like 1 sec it shifts down (to 1st - RPMs jump) then shifts to 2nd gear and from there it is fine. 3rd to 4th, to 5th is great, but 5th to 6th same issue, not as extreme, but similar. If i let go of gas when it should shift to 2nd gear, and wait like 2 sec, it will be in 2nd gear without jerking - Normal. Sometimes in Park there is this noise as though something metal is hitting another metal part, and I can feel it in car - but it goes away and only happens from time to time. Also Neutral on rare occasion works as Reverse - super rare. I did Stall test (per Hyundai procedure Bulletin 13-AT-007) - no issues. Dealer ran diagnostic - no Codes in transmission. Flushed fluid - didn't help. I drained fluid again, put new fluid in and checked ATF level per 13-AT-006 - no difference. Tested Solenoids - no problem there. What could be an issue with my transmission?? 2012 Sonata GLS 2.4L with 7k miles.
At 7k miles you shouldn't have to play with the fluid. Warranty issue - make them resolve it.
 

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Discussion Starter · #8 ·
Probably salvage title.
Yes, it is salvage title. It had water damage and drove fine for about 500 miles, but then all of a sudden it started acting up.
It used to be that I could not start moving, engine would rev but car would not move for like 5 sec - and then it will jump. Now it is alot better - as I have described above.
 

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Salvage due to water intrusion.. How deep of water ?

Water in trans ?? // strawberry milkshake ?? probably done toasted now..

Water intrusion to electrical connectors and rot ? Trans is just a box of rocks, it is a puppet of sorts,, wont do anything unless it receives electric signals from controller to do something
 

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Ouch - presumably you bought this on the cheap so perhaps now you have to invest some $ to get it right.
 

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Worth noting that 2nd and 6th use the same "clutch" to apply. Hyundai calls it the "2-6 brake". In second gear, it applies along with the underdrive brake. In sixth gear, it applies along with the overdrive clutch.

I think it's time for the dealer to plug in the GDS and drive the car and check the solenoid functionality and input/output speed sensor values. If they checked this at the dealer but the car didn't move, they just scanned for codes and checked some basic functions. They can "see" much more when the car is in motion.
Solenoids only do what the computer tells them to do, so any problems between the computer and the trans will cause trouble.
 

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I think what dmlexpert is trying to get at is the dealer should perform a driveability diagnostic. Take GDS with one guy driving and one guy monitoring live data in passenger seat. Flat rate at least an hours time if not more.
 

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I think what dmlexpert is trying to get at is the dealer should perform a driveability diagnostic. Take GDS with one guy driving and one guy monitoring live data in passenger seat. Flat rate at least an hours time if not more.
Exactly. Modern electronic transmissions are not "user serviceable" other than basic maintenance. These transmissions are "clutch to clutch" designs that require very precise timing of releasing one clutch as the other applies. Too much overlap and you get the flare (engine races) and you burn up the clutch packs. To little overlap and the geartrain binds up and you can break internal parts.

Regarding the OP saying that "once, neutral acted as reverse" - that sounds like a bad or misadjusted range selector. That also is a dealer "repair". To confirm that the issue is the range selector, try to start the car in N. If it won't start, the selector needs adjustment or replacement.
 

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Discussion Starter · #14 · (Edited)
Exactly. Modern electronic transmissions are not "user serviceable" other than basic maintenance. These transmissions are "clutch to clutch" designs that require very precise timing of releasing one clutch as the other applies. Too much overlap and you get the flare (engine races) and you burn up the clutch packs. To little overlap and the geartrain binds up and you can break internal parts.

Regarding the OP saying that "once, neutral acted as reverse" - that sounds like a bad or misadjusted range selector. That also is a dealer "repair". To confirm that the issue is the range selector, try to start the car in N. If it won't start, the selector needs adjustment or replacement.
Got it. I am wondering - what would it take to fix an issue you mention? Is it something which would be really deep in transmission? Could it be computer? The reason I ask is that if it is really deep in trany, some clutch discs/brakes or who knows what - I have a feeling it would not be something I could pull off, and therefore would not worth bothering. What do you think?
I poured some TransTune by SeaFoam and it does not fix anything so far - used it as instructed but no help from it (and I read it has helped ppl with "average" transmission issues.
BTW: since I have re-adjusted gear-selector and tried starting in N - no problem. So it might have fixed an issue of N acting as R as you mentioned.
 

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Discussion Starter · #15 · (Edited)
Worth noting that 2nd and 6th use the same "clutch" to apply. Hyundai calls it the "2-6 brake". In second gear, it applies along with the underdrive brake. In sixth gear, it applies along with the overdrive clutch.

I think it's time for the dealer to plug in the GDS and drive the car and check the solenoid functionality and input/output speed sensor values. If they checked this at the dealer but the car didn't move, they just scanned for codes and checked some basic functions. They can "see" much more when the car is in motion.
Solenoids only do what the computer tells them to do, so any problems between the computer and the trans will cause trouble.
They did seem to have done basic diagnostic and without actually driving it as you and Smoke1991 recomended :(.
All these issues started shortly after I drove care in Sport mode, but not sure if it was only a coincidence. Some people suggest that maybe Trany Filter might be to be blamed, which sort of does not sound like probable cause since other gears work fine.
Here is another thing I noticed: When it shifts to 3rd, car slows down, almost brakes a little bit, then after 2-3sec it completes shift and car accelerates (fairly smoothly and without jumping).
 

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Got it. I am wondering - what would it take to fix an issue you mention? Is it something which would be really deep in transmission? Could it be computer? The reason I ask is that if it is really deep in trany, some clutch discs/brakes or who knows what - I have a feeling it would not be something I could pull off, and therefore would not worth bothering. What do you think?
The 2-6 brake is just behind the torque converter and front pump, but it is rare for the plates to be damaged or destroyed at low mileage. If it were anything in the clutch pack, I would suspect the seals, and they're not the type of part you can buy locally or even order online. With that being said, the computer calculates the right amount of fluid to use to apply a given clutch, and it uses the solenoid to meter out that amount of fluid. So a bad solenoid or bad fluid can cause problems without the geartrain and clutches having any apparent damage. The dealer has a fancy laptop they can plug in and drive the car, and see what the computer is requesting, what the solenoids are delivering and the performance of the clutches based on these parameters. There is little point in replacing parts until it works because the parts are not cheap.
I poured some TransTune by SeaFoam and it does not fix anything so far - used it as instructed but no help from it (and I read it has helped ppl with "average" transmission issues.
In these newer clutch to clutch transmissions, the TransTune can cause more problems than it solves by changing the friction characteristics of the fluid. Today's ATF is no longer "Type A vs Dexron vs Type F". The Sonata uses Hyundai SP-IV and additives are not supported - meaning dealers and techs won't tell you to toss in a bottle of any kind of additive to address odd trans behavior.
They did seem to have done basic diagnostic and without actually driving it as you and Smoke1991 recomended :(.
All these issues started shortly after I drove care in Sport mode, but not sure if it was only a coincidence. Some people suggest that maybe Trany Filter might be to be blamed, which sort of does not sound like probable cause since other gears work fine.
Here is another thing I noticed: When it shifts to 3rd, car slows down, almost brakes a little bit, then after 2-3sec it completes shift and car accelerates (fairly smoothly and without jumping).
Any funky 2-3 and 5-6 shifting, whether upshift or downshift, can be explained in this image:



On the left is the layout of the three planetary gearsets, and the red box I added shows where the "drum" is positioned, and on the right is a drawing of what it looks like, along with the clutch plates that fit inside, making up the 3-5-R clutch. The "26/B" in the schematic is the 2-6 brake, with the plates meshing with the outer edge of that drum and splines in the transmission case. In 2nd and 6th, that brake locks this drum to the case so it can't turn. In 3rd and 5th (and Reverse too), the "35R/C" applies and connects this drum to the input shaft (engine power).

So when shifting 2 to 3, the brake needs to release so the drum can spin before the clutch applies to connect the drum to engine power. The hesitation you feel is the computer making sure the brake is released before the clutch applies. A few years ago, a software and solenoid issue led to early Sonata transaxles making a loud thump or bang before locking into limp-home fourth gear. The cause of the thump? In your minds eye, connect that drum to the engine ("35R/C") without releasing the brake ("26/B") and you realize that doing so locks the engine to the transmission case, trying to stop it dead (from 2000rpm) in its tracks. And that's not going to happen smoothly! In the early bug, it wasn't a total lockup but rather one applying a little too soon and the other releasing a little too late, so there was a thump for that millisecond binding of the gearset.

If your transmission has software, electrical, or hardware problems, or contaminated fluid or incorrect fluid or other outta-spec conditions, the computer will make the 2-3 shift progressively lazier because it doesn't allow full engine power until the speed sensors (input and output shafts) indicate there is no slippage in the clutch packs. That's the hesitation and dead-engine feeling- the computer is choking off engine power until the transaxle reports that the desired gear is locked in and ready to handle full engine torque.

Aren't you glad you asked?! :D
 

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My transmission is having issues switching from 1st to 2nd gear and same issue from 5th to 6th. What happens, (when attempting to switch from 1st to 2nd) RPMs rev up high (as though it is in Neutral) then after 2-3 sec it shifts, car jumps crazy and in like 1 sec it shifts down (to 1st - RPMs jump) then shifts to 2nd gear and from there it is fine. 3rd to 4th, to 5th is great, but 5th to 6th same issue, not as extreme, but similar. If i let go of gas when it should shift to 2nd gear, and wait like 2 sec, it will be in 2nd gear without jerking - Normal. Sometimes in Park there is this noise as though something metal is hitting another metal part, and I can feel it in car - but it goes away and only happens from time to time. Also Neutral on rare occasion works as Reverse - super rare. I did Stall test (per Hyundai procedure Bulletin 13-AT-007) - no issues. Dealer ran diagnostic - no Codes in transmission. Flushed fluid - didn't help. I drained fluid again, put new fluid in and checked ATF level per 13-AT-006 - no difference. Tested Solenoids - no problem there. What could be an issue with my transmission?? 2012 Sonata GLS 2.4L with 7k miles.
Have them run the codes. Chances are that may clear it. The factory solution is to remove and replace the transmission if required. The dealers do not rebuild them. I believe everything is internal.

I'm betting on the codes. I had a similar problem with a Kia and once the codes were cleared it never happened again.
 

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I've noticed on my 2011 GLS that sometimes this 2-3 gear race happens if I hit an incline when the shift occurs. For me this is a regular occurrence at one intersection where I'm cresting a small ridge as I accelerate through. On flat surfaces I've never noticed it.

I've wondered if I should mention it to my dealer but I've kind of passed it off as normal behavior. Thoughts from the learned members of this thread?
 

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Discussion Starter · #19 · (Edited)
The 2-6 brake is just behind the torque converter and front pump, but it is rare for the plates to be damaged or destroyed at low mileage. If it were anything in the clutch pack, I would suspect the seals, and they're not the type of part you can buy locally or even order online. With that being said, the computer calculates the right amount of fluid to use to apply a given clutch, and it uses the solenoid to meter out that amount of fluid. So a bad solenoid or bad fluid can cause problems without the geartrain and clutches having any apparent damage. The dealer has a fancy laptop they can plug in and drive the car, and see what the computer is requesting, what the solenoids are delivering and the performance of the clutches based on these parameters. There is little point in replacing parts until it works because the parts are not cheap.

In these newer clutch to clutch transmissions, the TransTune can cause more problems than it solves by changing the friction characteristics of the fluid. Today's ATF is no longer "Type A vs Dexron vs Type F". The Sonata uses Hyundai SP-IV and additives are not supported - meaning dealers and techs won't tell you to toss in a bottle of any kind of additive to address odd trans behavior.

Any funky 2-3 and 5-6 shifting, whether upshift or downshift, can be explained in this image:

On the left is the layout of the three planetary gearsets, and the red box I added shows where the "drum" is positioned, and on the right is a drawing of what it looks like, along with the clutch plates that fit inside, making up the 3-5-R clutch. The "26/B" in the schematic is the 2-6 brake, with the plates meshing with the outer edge of that drum and splines in the transmission case. In 2nd and 6th, that brake locks this drum to the case so it can't turn. In 3rd and 5th (and Reverse too), the "35R/C" applies and connects this drum to the input shaft (engine power).

So when shifting 2 to 3, the brake needs to release so the drum can spin before the clutch applies to connect the drum to engine power. The hesitation you feel is the computer making sure the brake is released before the clutch applies. A few years ago, a software and solenoid issue led to early Sonata transaxles making a loud thump or bang before locking into limp-home fourth gear. The cause of the thump? In your minds eye, connect that drum to the engine ("35R/C") without releasing the brake ("26/B") and you realize that doing so locks the engine to the transmission case, trying to stop it dead (from 2000rpm) in its tracks. And that's not going to happen smoothly! In the early bug, it wasn't a total lockup but rather one applying a little too soon and the other releasing a little too late, so there was a thump for that millisecond binding of the gearset.

If your transmission has software, electrical, or hardware problems, or contaminated fluid or incorrect fluid or other outta-spec conditions, the computer will make the 2-3 shift progressively lazier because it doesn't allow full engine power until the speed sensors (input and output shafts) indicate there is no slippage in the clutch packs. That's the hesitation and dead-engine feeling- the computer is choking off engine power until the transaxle reports that the desired gear is locked in and ready to handle full engine torque.

Aren't you glad you asked?! :D
Info like this is hard to find! It's like crash course in modern-time Transmissions (and man are they not sophisticated?!). Thank You!
If I understand it correctly - 2-6 Brake is the reason car revs up when attempting to switch to 2nd and 6th gears (let me know if i got it right/wrong). Seeing that it is unlikely that 2-6 brake is damaged by water, something is either wrong with Solenoids or Computer controlling them?
As far as clutch - I did clutch test and they are not slipping in the modes I could test - D, R, 1 & 2 gears (and believe 4th as well).
There are 8 solenoids and looking at tables I am wondering if they are doing double-duty. Looking at tables and one lists 26 N-L in Solenoid section, while other table lists 26 B in Brake section.
BTW: how do you know so much about transmissions and in such detail? It is truly impressive!:)
 

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Discussion Starter · #20 ·
Have them run the codes. Chances are that may clear it. The factory solution is to remove and replace the transmission if required. The dealers do not rebuild them. I believe everything is internal.

I'm betting on the codes. I had a similar problem with a Kia and once the codes were cleared it never happened again.
They scanned but no codes were in trany nor anything trany-related in computer; they reset everything anyways, but it did absolutely nothing.
 
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