Transmission "Learning"

SHORT VERSION: Is the time for the transmission to "re-learn" longer than 2 weeks or 400 miles? And even if does take longer than 2 weeks, shouldn't the transmission jumping/jerking/stuttering gradually get better?

STORY VERSION: I have a 2015 Legacy with about 75K miles on it.

3 weeks ago, I noticed the vehicle was suddenly and frequently jerking/jumping/stuttering when upshifting and occasionally when downshifting. If I slowly and overly cautiously accelerate, it would be minimal, but still when the car would downshift, the problem was there. So, 2 days after I noticed the problem I brought it into the dealership, which was great because I had plans to do my 75K mile maintenance anyway; two birds one stone.

While in the shop, the mechanic re-installed the firmware for the transmission, under the idea that the transmission "forgot" how it was programmed.

I got the car back and immediately noticed the transmission was still jerking. The shop representative told me that it would take a few days for the software to fully grab hold, but soon the problem would be gone.

After a week and about 200miles , the problem was still there, so I returned it to the same dealership shop. After further inspection, they figured out that the transmission housing was cracked and replaced it. I got the car back, and just like before it was a little jumpy, but I recalled the conversation about the transmission needing time to learn how I drive.

Well 2 weeks and 400 miles after the previous shop visit, the problem is still there but worse. Subaru's master mechanic informs me that this is normal, especially with multiple drivers and that it will simply take time. Well only I drive me vehicle and it's been over 400 miles and I'm seeing no change.

Having disconnected the battery for a period of time, I know the engine going through something similar, but after a couple of days, I notice the engine picking up on my trends, and after a at most week the two of us are in tune.

Is the time for the transmission to "re-learn" longer than 2 weeks or 400 miles? And even if does take longer than 2 weeks, shouldn't the transmission jumping/jerking/stuttering gradually get better?

... Is the time for the transmission to "re-learn" longer than 2 weeks or 400 miles? ...

It wouldn’t surprise me if it was, but I thought it would get progressively better. My current 2019 Outback took a long time to learn both CVT & throttle learning when the car was new, & I just drive my new cars normally (I don’t believe in pussy footing new cars).

In the subaruoutback.org forums ‘2020 XT Throttle response’ topic, cardoc in post #71 states that normal throttle learning can take 500 miles. So I expect CVT learning could be similar.

Just in case what you are experiencing is also throttle learning I would suggest trying the throttle learning procedure as posted by SilverOnyx in post #57 of that same topic which was a translation of the Japanese link posted by yoyash.

I use a different throttle learning procedure to that, but that throttle learning procedure which is called PE-CO PE-CO in Japan could be worth trying to see if it helps the CVT learning.

If you do try it, would you let us know if it helps?

This puts me at ease a bit. I'm right under 500miles and the transmission still seems to be "learning", especially when driving shortly after a cold start. But seeing as this is mostly normal, I'll give it to about 700 miles.

I did hear back from the dealership's service department. They said it the problem remained for another week or normal driving they'd have to get a second opinion from another dealership, which does not make me feel warm and fuzzy.

I'll try to remedies based on the post you linked to see if those help. If they don't, I may try removing the battery to reset the system and give it a bit more time before bringing it to another dealership. Truth be told, this dealership has often erked me the wrong way, but it's also the closest dealership to me.

... I may try removing the battery to reset the system ...

If it was me, I wouldn’t do that because your throttle learning may be lost & you may need to do a re-learn procedure. However, I don’t know what a disconnect & re-connect of the battery does to CVT learning (does anyone know for certain?). If you do decide to do that, then carry out a throttle learning procedure after re-connecting the battery.

In addition to what I posted in my last post, below are three ECU reset procedures with throttle learning procedures that I have used over the years that have been recommended to me:

One version:

1. Before disconnecting the battery, turn OFF the engine, climate control a/c, SatNav/sound system & lights so there is minimum load on the battery.
   
2. Disconnect the battery.
   
3. Press the brake pedal a few times to remove any residual current from the system.
   
4. After at least 30 seconds reconnect the battery (this time can be extended just to make sure any capacitors still holding a charge have discharged).
   
5. Wait at least 15 seconds then turn the ignition to ON (two presses of the start/stop push button) but don’t start the engine (keep foot off the brake pedal when pressing the start/stop button so that the engine doesn’t start). (make sure the climate control a/c, SatNav/sound system & lights are still turned OFF).
   
6. Wait at least another 15 seconds (during this period you may hear various clicks & other sounds).
   
7. Start the engine & let it idle for at least 60 seconds without touching the accelerator or brake (keep the climate control a/c, SatNav/sound system & lights turned OFF during this period).
   
8. Take the car for a good drive. The throttle will be unresponsive for a while & fuel economy will be poor for the first approximately 3/4 tank of fuel.

Another version:

1. Turn off all lights and accessories (no A/C, lights, blower, radio, etc.).
   
2. Disconnect battery for 30 min.
   
3. Re-connect battery.
   
4. Turn key to ON position for 15 seconds (throttle body has a chance to go through a check sweep during this period; do not let engine turn over).
   
5. Start car and let it idle without any load (no A/C, lights, blower, radio, etc.).
   
6. Leave engine running for 10 minutes, never loading, never touching accelerator.
   
7. Turn off engine and leave key in off position for at least 20 seconds.
   
8. Turn key back to the ON position for 15 seconds without starting engine.
   
9. Start engine and leave idling for 5 minutes without loading or touching accelerator.
   
10. Turn off engine and wait 20 seconds before restarting.
    
11. Go for a drive.

And another version: (Posted by 'tigger73' on: http://legacygt.com/forums/showthread.php/reset-cvt-fuzzy-logic-procedure-253390.html?t=253390 who got the info from Matt (throttlehappy) who tunes cars.

1. Disconnect battery.
   
2. Put foot on brake for 10 seconds (drain electrical system).
   
3. Reconnect battery.
   
4. Turn ignition to "ON" position.
   
5. Turn ignition "OFF".
   
6. Turn ignition to "ON" position.
   
7. Turn ignition "OFF".
   
8. Wait 15 seconds.
   
9. Start car.
   
10. Idle for 60 seconds.
    
11. Drive for 30 minutes on light/moderate throttle.

After any of the above three you will need to re-initialise the auto up/down for the driver’s side window (& front passenger window if your car has auto up/down for that as well).

There was another topic either on this forum or on subaruoutback.org forums that had similar issues to what you have with your CVT. If I find it I’ll post the link.

I forgot to mention this. According to Subaru, overfilling engine oil can cause CVT surging, jerking & not shifting properly.

I would check your engine oil level cold when on a level surface (both important) before trying anything else just in case this is the cause.

See the below copy in part of the June 2014 Subaru TechTIPS.

2014.06JunTechTIPS.pdf

It's been a busy week at work due to the COVID-19. But I wanted quickly update you.

I check the oi frequently because the vehicle tends to burn a bit of oil from time to time. But beyond that, I didn't check anything else mostly because the vehicle had just gotten its 75K service and I got a list of fluids that were checked and topped up.

I recently surpassed 600miles from the point of the work was done. The jerking has decreased a noticable amount. Originally it felt like an old hydraulics car jumping down the street, now it just more occasionally and it's just one or two skips rather than a string of them.

I've cancelled my appointment at the dealership to give the issue more time to continue resolving itself. Ultimately I have a lot more time on my extended warranty, so I'm not too concerned. I'm hoping by the 800th mile, the problem is near nonexistent.

I did NOT try any of the techniques you mentioned for fear of resetting/restarting the learning period, but I did send them to my phone in the event that I got fed up.

All that, to say thanks for hopping into this thread and giving me a few ideas as well as some peace of mind.

Now I just have to deal with the dealership who's still yet to contact my third-party warranty company regarding the repairs.

Thanks for the update. That is good news.

In regards to your engine oil level; it has been my experience that dealers tend to slightly overfill engine oil. From what I’ve read on the various US forums this appears to also be the case in the US.