Forester suffers studder / vibration under acceleration under one condition - highway traffic

[Sousuke]

I'm having an issue with my 2014 Forester where it vibrates at the Torque converter speeds (19 to 35 mph) but I'm not sure it is the Torque converter because it happens only under certain conditions.

I get it when on the highway or country road when i've been driving 60 - 70 miles and hr and hit traffic. It will drag in that 19-35 range like that all the way until I speed up or get off the highway on to city streets. I can be doing stop and go on the highway for a mile and its an issue and then when get to an off ramp and start driving on street grid it disappears despite similar driving pattern.

Mid to high acceleration will stop the vibration / studder and while it makes no noise from inside the car, I've had the windows down where I'm driving my a wall that can reflect noise and I hear a light rattle similar to a heat shield rattle (which might be the case)

 

[Ecmbuster]

And the model is? And the engine is? And the transmission is?

 

[Sousuke]

And the model is? And the engine is? And the transmission is?

View attachment 1653

I'm sorry! Totally blanked that.

Its a 2014 2.5 limited

So it has the naturally aspirated FB25B with the CVT TR690

 

[Ecmbuster]

Be aware that this type of technology needs extra care meaning the correct CVT oil and filter regular changes. A qualified Technician with the Subaru SSM (Subaru Select Monitor) application can test the correct transmission shift points if it is an issue. The engine (ECM) controller can also be monitored for faults. That also holds true with the CVT transmission controller. If any network controlled controller produces any faults, those faults need to be addressed. Network faults also include the ABS system. The ECM, TCM and ABS can create faults that are attributed to your concern. Have the system tested with your concerns about drivability and the noises heard while driving.

 

[Sousuke]

Be aware that this type of technology needs extra care meaning the correct CVT oil and filter regular changes. A qualified Technician with the Subaru SSM (Subaru Select Monitor) application can test the correct transmission shift points if it is an issue. The engine (ECM) controller can also be monitored for faults. That also holds true with the CVT transmission controller. If any network controlled controller produces any faults, those faults need to be addressed. Network faults also include the ABS system. The ECM, TCM and ABS can create faults that are attributed to your concern. Have the system tested with your concerns about drivability and the noises heard while driving.

The CVT was serviced about 5000 miles ago. I did take it to the dealer a month ago but they could not replicate and found no faults. I may go to the dealer near my work where I get more face time with the techs

 

[Sousuke]

I'll just add this here in case someone else happens to be looking for a similar issue.

I found on another forum a recommendation that worked (so far) for me. They were recommending this for a 2017 Forester with a CVT but its seemed to work for me too.

At startup, after letting the engine warm for a minute, shift in Neutral and let off brake for a sec. Then reengage brake and shift into gear (be it R or D). This doesn't need to be done thereafter. I've been doing this for the last two weeks and the issue hasn't resurfaced. Prior to this I was having an issue every time I hit traffic doing 20-30mph after the car is warm (+30 min). Since then I've run into traffic 5 or 6 times, including a 4 hour round trip drive with hills and no issues.

In the other forum, it was inferred that going into Neutral does something in terms of the software.