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2020 Ascent transmission shudder

34K views 60 replies 20 participants last post by  robn30 
#1 ·
Hey all,
I have a 2020 Ascent Premium with 15,000 miles on it purchased 1 year ago. It seems I've always noticed a slight shudder, like driving over the center dots or the road edge that is designed to wake a driver up when lightly using the throttle and a hill is approached. It's like I'm just too light on the throttle, the car tries to down shift and it's hunting between the downshift and the taller gear. I know these are CVT's but that's what I and my wife feel. It's slowly gotten worse, so when I took the car in to the dealer about pulsing brakes, (they said rotors warped and replacing), they looked into it. They could not replicate the sensation, so they escalated it to someone referred to as the area rep. The rep called me and I described the sensation and exactly what local road areas this is most prevalent. He told me he would check tomorrow and that if he couldn't get it to happen, I will meet him and demonstrate.
I know of the 2019 problems but I don't think I've heard of 2020's with this problem. If anyone can shed light that I can pass along to the rep, that would be great!
 
#2 ·
At what speeds and RPMs do you notice this shudder?
 
#3 ·
Two occasions;
Flat road at 55-60mph, as I start up a slight grade, keeping my foot steady on the throttle, not adding any, the transmission feels like it's trying to downshift, but then instantly upshifts again, repeat rapid-fire for a few seconds, then stops. RPM's slightly below 2K then downshift to around 22K, maybe 23K?
Second occasion is on a fairly steep uphill twisty narrow road at between 30 and 40 mph, steady throttle. Near the top of the hill, it gets real bad with hunting for the right gear.
I realize these don't have gears, but that's what it feels like. Not sure of the RPM's as I'm actively driving a narrow twisty road and don't check.
 
#12 ·
Two occasions;
Flat road at 55-60mph, as I start up a slight grade, keeping my foot steady on the throttle, not adding any, the transmission feels like it's trying to downshift, but then instantly upshifts again, repeat rapid-fire for a few seconds, then stops. RPM's slightly below 2K then downshift to around 22K, maybe 23K?
Second occasion is on a fairly steep uphill twisty narrow road at between 30 and 40 mph, steady throttle. Near the top of the hill, it gets real bad with hunting for the right gear.
I realize these don't have gears, but that's what it feels like. Not sure of the RPM's as I'm actively driving a narrow twisty road and don't check.
I have a 2019 that has done this since some time around 5-10k miles. It had a reprogram of the ECU and did it worse after, then better, now worse. It shudders in scenarios just as you describe. I described it to the service manager once riding with me for a different issue, and he didn't seem concerned. The 2019s do have a 100k CVT warranty if they have not been replaced already and underwent the ECU reprogram, so that makes me feel better.
 
#4 ·
Mine did that immediately following a reprogram. In two weeks, it never did it again (and that was about 30,000 miles ago). It should not be hunting that many times at your mileage. I'd have it checked out - as you know, key thing will be them being able to replicate it. :(
 
#5 ·
Fortunately the rep I spoke on the phone with and will be performing the test drive said he would call me if he couldn't replicate and wife and I could test it with him.
Also, as long as I got it on record, my hope is that it will cover me if it fails past my 3year/36,000 mile factory warranty. Is that a valid hope or should I just bite the bullet and get the warranty? I trade in every 4 to 5 years with about 20K miles a year/80,000 miles.
 
#6 ·
I can't answer to how Subaru will specifically handle it for you, but, in the past, I know they've sometimes made allowances within "reasonable" amounts of time/miles. For instance, if you come back at 142,302 miles, I doubt they're helping you. ;)
 
#8 ·
I've had this issue for a couple of months. currently have about 16000 miles. mine is usually when I'm speeding back up after slowing down. Service department couldn't replicate (because reasons) but it was reported. It is a real problem so more people need to report it
 
#9 · (Edited)
My 2020 Limited is starting to stutter as well - it happens most consistently on a stretch of road on the way home. When traveling around 40 mph with foot steady on the gas pedal - when it begins a gradual up hill & I give it some gas to maintain speed, it stutters.

I am also getting the clunk when shifting from reverse to drive (with car completely stopped, foot firmly on brake and I never remove my foot from the brake or give it gas in drive until the shift is complete).

Very disappointing - but that's what warranty is for.

Was planning a service visit in the near future for squealing brakes - I guess I will get them started with looking into the shuttering and clunking as well.

(edit) Should I wait until the squeally brakes and transmission issues are resolved before having them go at the right front clunk?

 
#10 ·
I just scheduled a service appointment for these issues. Braking above 60mph vibrates and shutters aggressively. I notice a lag in power as I try to accelerate at about 2,000rpm. I've also had a knocking noise in my rear passenger wheel well that I've heard since the day I bought the car but the dealership has not been able to identify the issue yet. Not sure if anyone else has noticed that noise. Hoping warranty will cover these issues.
 
#13 ·
Our 2020 has started to shudder momentarily as well. It usually happens during transitions to higher RPM (such as when applying more throttle to climb a hill or speed up). It's only a brief shudder, like if you ran over only three or four raised paint bars on the road. But I will say that it's occuring with somewhat increased frequency. It's still not "common" for it to happen, and I'm pretty sure that I couldn't get the car to do it on demand, such as on a ride-along with a technician. I'd say it happens once every three or four trips or so.

We have about 7,500 miles on ours now.
 
#15 ·
Could be still learning? Are you two experiencing a true shudder, or it changing gear ratios up and down quickly?

Your power train warranty is 5 years, or 60,000 miles (whichever comes first), but it couldn't hurt to at least get it logged in writing with your service centers.

If I see anything similar, with a cause, I'll let you both know.
 
#17 ·
Hmmm... I have some thoughts...
Thought 01:
If you can replicate it, can you see if you can catch the RPM's jumping up and down about a thousand RPM or so?

I've seen it "hunt and peck" for a fake gear ratio. Mine did that after an ECU update about 23,000 miles ago, then resolved itself in the first thousand or two thousand miles (hard to remember, because I drive a lot... could have been 5,000 even), and never did it again. Others have needed an ECU update to resolve it. And, finally, IIRC, there was someone who had a bad valve body cause it.

Thought 02:
If it's not that, it is possible it's the AWD transfer clutch chattering/shuddering. Usually, it happens on sharp turns, but, I've heard of it happening on hills as the system tries to transfer power to the wheels that need it. If it is that, there's a very simple procedure to break it in properly/again. Go to an empty parking lot where you won't get arrested or ticketed for looking crazy, and do this procedure:

While holding the steering in the full lock (left or right) position, drive the vehicle in “D” range at about 3 MPH then turn the steering wheel to full lock in the opposite direction to complete a “Figure 8”. Vary the vehicle speed by accelerating and braking. After completing about 10 figure eights, road test to confirm if the condition has changed.
This procedure may have to be performed more than once to achieve the desired results.
If it's the AWD Transfer Clutch, that should resolve the issue. May take anywhere from 1-3 times to break it in.

Anyways, hope something there helps. I have a strong leaning towards the AWD transfer clutch, even though it's not listed for the specific symptoms you two are describing, especially since you're saying it's getting better (normal driving will usually eventually break it in).

Please keep us posted.

 
#20 ·
It's definitely not the first thing you mentioned, Robert, where the RPM would flare by even a few hundred RPM (at least in our case). The engine speed doesn't seem to change during this event, except for the increase in engine speed called for with the gas pedal. It feels like the shudder happens when the system initiates the ratio change for acceleration, but it definitely does not appear that the system is "slipping" or anything like that.

If it's not that, it is possible it's the AWD transfer clutch chattering/shuddering. Usually, it happens on sharp turns, but, I've heard of it happening on hills as the system tries to transfer power to the wheels that need it. If it is that, there's a very simple procedure to break it in properly/again. Go to an empty parking lot where you won't get arrested or ticketed for looking crazy, and do this procedure:...
Also rare, but I have felt this before when accelerating from a stop while also turning (like after stopped waiting to make a left turn). And I will say the brief shudder at speed does indeed feel a lot like the low-speed shudder sometimes felt when turning.

I have not yet done that manual break-in procedure, but maybe it's worth trying.
 
#19 ·
Excellent! Would love to hear what they figure out.
 
#25 ·
Every time I drive this Ascent I wonder if I should just deal with it and keep it or get rid of it.
I teeter on that exact same fence every time I drive my 2020 Limited (7500 miles) - every single drive.

It used to only shutter & stutter when at the transition from coasting to lightly rolling onto the throttle at the base of inclines in the road. Now it is starting to do it more and more consistently from coasting to rolling onto the throttle on flat roads.

I have taken into the dealer but also got the "the tech didn't notice anything abnormal for the vehicle" response. Going to try again when I can actually ride along with the tech and take him to some nearby locations where it shutter-stutters consistently.

I haven't bothered to write SOA - I gather that SOA are great when a vehicle is totally kaput but I don't have the patience (or time to waste) to write SOA just to get the inevitable standard "contact your dealer" boilerplate brush off.

I really love the Ascent in concept and form factor - a great big 3 row Subaru with tons of space - what's not to love about it? Well, for me, it's the sloppy drive train on my 45 thousand dollar vehicle - the absolute sloppyist (and most annoying) drive train performance of any car I have ever owned.

Now, mind you, I have gotten over the rediculous (and unpopular) shift simulations - I've even gotten myself to a point of peace regarding the inexplicable and annoying acceleration bog down by training myself to significantly increase throttle just before the drop out to smooth out the bog down to make it tolerable. But, I will only try once more with the dealer to get the shutter-stutter resolved - one more "nothing abnormal here - that's how the Ascent was engineered to drive" response and I'm out...

My wife won't drive it anymore and I can't really blame her - there are days when I grab the keys to her CrossTrek instead when I am just not in the mood to tolerate my quirky Ascent.

I just want my 45 thousand dollar vehicle to drive as if the drive train knows what to do (and does it) without stumbling over itself until it decides. I realize there is a ton of tech built into today's new cars but I don't think I am asking too much here... ☹

This is my 4th Subaru - my first one was a 1988 Loyale Wagon Turbo. Ironically, even though I loved its concept and form factor, it too had a major drive train quirk that resulted in a horribly annoying "fish-nibbling" hesitation throughout the throttle range. It was out of warranty and after being told by Subaru maintenance techs that it would probably drive better if they replaced the turbo and/or the torque converter, I ended the relationship.

View attachment 7175

As mentioned, I am teetering with this Ascent. My initial strategy was to ride it out and hope that if the transmission was going to fail, that it did so before the warranty ends. But, now, I am about at my fill with the repeated guessing each time I apply throttle - is it going to give me the shimmy-shake & stutter-shutter on this acceleration or is this going one to be a smooth one?... and lather, rinse, repeat, ad nauseum.

Maybe the next time I take it in for this, I will be able to make it happen with a service tech in the vehicle and they will hear and/or feel it and know how to resolve it. Who knows?

What I do know is that dealing with it is wearing on me.
 
#28 ·
I have a 2021 Limited Ascent with 3000 miles on it. It is experiencing the same issues described by numerous people. When constantly accelerating up a slight incline it will stutter. This seems to happen in the 25 to 35 MPH range. It seems to happen when accelerating after NOT stopping. If I accelerate after a complete stop, it doesn't seem to happen. If I drive the car more aggressively it doesn't happen. It happens when I am accelerating lightly. I brought it to the dealership a couple of days ago. They couldn't reproduce the issue which isn't surprising because it is fairly intermittent.

I am also experiencing an issue when braking. I have less detail about when this happens because it is less frequent. Right now I would say it happens when braking from around 60 MPH. It sounds like a flat tire - a whomp whomp whomp.... I would say a warped rotor but this doesn't make sense because it is very intermittent. Something not disengaging properly in the CVT when braking?? Super frustrating. Love this car otherwise.
 
#29 · (Edited)
I have been researching this more. Looks like Subaru posted a TSB for this exact issue. Please see the following: MC-10185089-0001.pdf (nhtsa.gov) . The issue people are describing seems to be "chain slip". Interested in if people agree this is the issue?

Looks like I am going to make my service guys drive around with me with his computer hooked up to my car. The fix seems to be to replace the transmission.
 
#30 ·
@MAX_S

If that chain slips, you'll have no doubts unless your radio is turned all the way up. It screeches quite "nicely" :(

Check the 2m30s mark, and listen from there.



It looks and sounds like that. Harsh shifting has nothing to do with chain slip. As for the TSB, my understanding is the clutch pack discussed is the applicable part for the 2021's, not the chain slipping - the 2021's don't have the original harness that caused chain slip.

And, no, the fix isn't as simple as to replace the transmission. In the event of chain slip, the harness, transmission control module and CVT get replaced. In the event of the clutch packs not having been broken in, they clear and start the relearn on the system and test again. In the event clutch slip is detected at a certain point, then, the CVT gets replaced.

That TSB is quite complex, and, the dealership has a bunch of tests to go through to determine which way down the diagnoses trees, they need to go - and what the solution will be.
 
#31 ·
My 2019 Ascent has 18,000 miles on the odometer. There is what feels like a transmission stumble or stutter at speeds between 25 and 35 mph under light to moderate throttle. I have an appointment for a dealer’s technician to investigate the problem. I’m not optimistic, though since the service writer said he’s never heard of this kind of problem before.
 
#32 ·
If it feels like very brief changes in gears (like it briefly upshifts then immediately downshifts again), I think several of us notice that. I'm almost certain this is not a mechanical thing. Ours does it most often when accelerating from a slower speed (such as after turning a corner) and applying about 25-30% throttle (as displayed by the throttle % widget on the dash-top screen). If I give it more throttle than that, then it usually doesn't do it. I think it's part of the programming. I don't know whether it gets "confused" and doesn't know quite what to do or if that sensation of shifting is intentional (which would be out of character -- the CVT is otherwise smooth except for the simulated step shifts at much higher throttle openings).
 
#35 · (Edited)
2019 owner with 26k beautiful miles chiming in to validate and also not cause alarm.

But first, let me say this is a minor quirk to me (like the constant dinging if you open the driver door before turning off the ignition ;)). I'm a huge fan of this car (it's our 1st Subaru) and it has proven to be perfect for our family and I would not hesitate to recommend it.

Now to the topic at hand. I too have noticed what's described as this stumble, stutter, etc occasionally occurring. For our driving habits, the moments seem to be when coming out of a round-about where I've coasted/braked down to a speed <25mph, RPMs are low as expected and I start to add "a touch of throttle" coming out of the round-about to get back to 30mph. As well as an instance or two when coasting/slowing to <25mph like approaching a 'red light' (as someone said above), then adding a small amount of throttle, it sorta 'stumbles'. If I slow way down below say <12mph, this will not occur. I also have never experienced it >35mph. The conditions have to be perfect, it doesn't happen every trip through these round-abouts.

From my (just enough, garage mechanic, but no expert) perspective, it seems like the drivetrain is responding to my gentle ask for thrust by suddenly diving into a lower gear ratio (like 6 or 7th gear) while the torque converter is still in lock-up (because of the vehicle speed). Then it quickly realizes what it has done will not work, so it un-locks the torque converter, raises the gear ratio to 're-compose itself' and things carry on like normal. I'm not convinced it's a 'slip' of anything.

I suspect it's also difficult to reliably reproduce because the powertrain learns and adjusts for the smoothest experience possible. Sometimes within a short period. If I drive throttle-conservative and then 'have a bit of fun' accelerating on an on-ramp. I notice that it will be a bit more aggressive with it's 'shifting' during the rest of my drive, particularly starting from stops because it's anticipating I will be 'throttle heavy' as a pattern. I also notice this after I unhook my boat. The car is simply used to needing to be more aggressive from a stop. Without this dynamic learning, we might be complaining about the poor performance when trying to tow things.

IMHO, it's not bad, or a problem, just different. For me it's well worth it to have the power, torque, traction available when I need it, but still a very smooth driving experience and decent MPG for it's size/weight and capabilities.

If I can find some time, I'd like to reproduce and capture the speed, throttle, CVT ratio and lockup with the ActiveOBD app on my phone.

fwiw
 
#36 ·
For our driving habits, the moments seem to be when coming out of a round-about where I've coasted/braked down to a speed <25mph, RPMs are low as expected and I start to add "a touch of throttle" coming out of the round-about to get back to 30mph. As well as an instance or two when coasting/slowing to <25mph like approaching a 'red light' (as someone said above), then adding a small amount of throttle, it sorta 'stumbles'. If I slow way down below say <12mph, this will not occur. I also have never experienced it >35mph. The conditions have to be perfect, it doesn't happen every trip through these round-abouts.
These are the exact types of scenarios where it happens for us, too. It does seem like the transmission is allowed to do something that "won't work", and it then tries to correct for that.

If I can find some time, I'd like to reproduce and capture the speed, throttle, CVT ratio and lockup with the ActiveOBD app on my phone.
I've done this quite a lot myself, though not with any images to share. I was quite surprised how often the torque converter is engaged when driving. It's almost always engaged for me, even during these types of mistaken shifting. It's the ratios changing, not the converter doing anything. And that's probably why it's pretty apparent in the car -- there's no slip to be had anywhere -- so you feel it in the cabin as a pretty apparent "shift". After about 10-15 mph, the torque converter is nearly always engaged in our car, even at high throttle. It does make sense -- about the only time a modern stepped automatic unlocks the converter is to execute a shift. CVTs can do that seemlessly, so Subaru keeps the converter locked up in these (at least as far as I've found).

I really like the operation of the CVT, and its driving modes. I wish some more refinement could be added to the programming to prevent things like this from happening.
 
#40 ·
If you get a chance, can you share the update information? It is usually somewhere on your service order.
 
#44 ·
After dealing with this shudder now for almost another 2 years, Subaru finally admits there is a recall and 3 weeks ago did a software upgrade. They said their code reader did not indicate a transmission chain slippage, or else they would shotgun replace the tranny. For two weeks the Ascent shifted harshly. I thought CVT meant constant velocity transmission and that I would not feel these shifts. It's like my wife is learning to drive a stick shift! It's C R A P ! Also, my mileage dropped by 30%, from 24mpg to 17mpg. Fast forward to this week. I make another appointment to have them look at this again. But wouldn't you know it, over the weekend, I have not noticed the shudder, the harsh shifting and my milage is up to 22.5mph. I presume the mileage was a learning curve for the car's computer, but the shifting lurch and the shudder, I don't know... I told the service tech the milage is improving but for a CVT, I didn't think I should feel my body get tossed between the shoulder harness and the seat back every time it shifts. Also, for some reason, I got a new oil leak. It's the filter. It's overflowing that cup thing it sits in. I think the filter is just loose, but since the car is due for an oil change, I told them about that as well. This afternoon, they called said they wanted to keep it overnight and let some roving tech guy look at it tomorrow. I presume some regional tech or something? I don't know. My guess is that since I reported this issue at least 3 times now, with 2 of the times contacting SOA, that the regional guy is tatamount to kicking this upstairs. Again, I do not know.
They gave me a crosstrek as a loaner. Nice car, peppy but I fell into the seat, being used to the Ascent's higher seat. And no motors on the seat, so not sure how to adjust. PLUS it says it's getting 47mpg! Can that be right? I reset one of the odometers and drove it around for 10 miles and that odo reading shows 45mpg, so maybe... I don't think it's a hybred as there's no tag on the rear hatch that says it is. Looking under the hood, I see the standard boxer 4 engine.
 
#45 ·
I suggest having another dealership look at it.
 
#46 ·
The problem is less shudder, but still there. The dealer called ME. I didn't have to call him. Well, for the full story, the dealership emailed me to ask if I was happy with the service I just had. I replied back that the problem was still there, and that it was disappointing to have a problem on a car that I make over $760 a month payments on. I also mentioned that if they could make me an offer I couldn't refuse as a trade-in on another Ascent, I'd be up for that. They said someone would contact me this week. They did and I dropped off the car yesterday morning at 9am. I then set the Driver Alert Settings:
1. Boundry Alert to .1 mile
2. Speed Alert to 70mph
3. Curfew Alert to 5pm to 5am

It's been two days now and the car has not moved. Using the Locate Vehicle feature, it's been parked on their back lot, a dirt lot used for long term storage I presume. It's at least .1 mile to move it to the shop area. I wonder if they are just going to sit on it, then call me to tell me they didn't have any symptoms. We'll see....

One more thing; full disclosure:
My wife and I have some friends that it turns out the husband is the uncle of this dealership's owner. The owner's mother and my friend are brother and sister. It was owned by mother and father, then they retired and sonny boy has taken things over. I casually mentioned that my wife was talking to a friend, cars came up and friend said her husband's nephew owns the Subaru dealership to the guy emailing me. Turns out the guy emailing me IS the owner and that my friend is 'Uncle Bill'. Ha! I have no idea if that will escalate or not. Since I mentioned perhaps a trade-in for a replacement vehicle was an option I'd entertain, who knows. Maybe they will do that. I'd swap for the loaner for example.

And one last thing:
this time when I dropped off, they had me stay with my car and took out an ipad of some sort to enter the information and to take photos of the car. Then I was allowed into the service writer. I asked him what that was about. It's something new at Subaru dealerships and they were being trained on this new procedure to write up the cars coming in for service or repairs. They did the same with the loaner car they gave me: used an ipad and took photos.
 
#47 ·
Update:
Service department could not repeat the problem after keeping it a week and invited me to take a test ride with a tech who had a tether tied into the OBDII port with a laptop. We went for a drive, and it did the shudder thing 4 or 5 times within a few miles. The tech was blown away that it did since he couldn't get it to perform. They kept the car and I the loaner. 2 days later, I get a call from service department, they expect the Subaru will authorize a replacement transmission and ordered one in anticipation. The other option is that they pull the tranny and repair it. However, they said that they have never repaired one, they always are replaced and returned to factory for study.
So I expect I'm getting a new tranny.
 
#48 ·
The other option is that they pull the tranny and repair it. However, they said that they have never repaired one, they always are replaced and returned to factory for study.
It's not dealer repairable by any dealer, other than the transfer clutch. Replacement only.
 
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