I know that the engine/trans combo is not the same as any of the Foresters, but thought I would post here for some advice since there are many more members here than on any of the XV forums.
What happens, is that on a cold start (car has been sitting overnight), I turn the key, it starts, then about half a second later this loud thunk and grinding sound happens (only lasts for a second or so), the RPMs drop significantly, then everything returns to normal. Usually.
I had this happen once a couple of months ago, but it caught me off guard and I didn't exactly realize what happened. This past couple of weeks, it has done it almost everyday. Once when the thunk/grinding happened it caused the engine to stall and I was unable to restart, until I tried 15 minutes later or so. There is no check engine light on. I changed my own oil last Friday, don't think this has anything to do with it, but thought I'd mention it. This problem started before the oil change and has continued after.
Also, sometimes when sitting at a stoplight a few minutes after start up (there is one by my apartment that I have sat at for up to 5 minutes) it feels as though the engine is stumbling or misfiring. I have not noticed any drop in RPM when it happens, but it can be felt throughout the car. It was occurring every 15 seconds or so (even tried shifting CVT into neutral to see if that was related, but did not change) then did not seem to do it for the rest of my journey.
Planning on taking it to Subaru when I can schedule the fiance to pick me up (probably going to have to leave it overnight so they can start it in the morning, otherwise it probably won't thunk/grind).
I have taken a couple of videos with my phone (didn't catch the one where it stalled the car), let me know if you have any ideas of what this could be. Make sure your volume is up.
Videos were taken on two separate days. First one was yesterday, second was today.
XV Problem - YouTube
XV Problem Vid 2 - YouTube