Thanks greatly to both of you for the suggestions/insight. My confusion is that if it ran decently (smooth), albeit with reduced power, mileage, and a lot of noise from the belt, why would it now be running rough? Is it probable that running for so long on a loose timing belt damaged some valves? All the timing marks seem to line up properly. I counted the spacing of the teeth multiple times (54.5, 51.

I feel it should be noted that when I gave it a little gas, it bogged down before revving slightly.Īfter tearing it all back apart, the timing looks fine. (I'm terrible at conveying car sounds-someone with experience might say it sounds nothing like a misfire.) Regardless, my impression was that the belt was off a tooth somewhere. Everything seemed like it going great until I get to starting it up. I was careful and meticulous and lining up the timing marks. I've replaced the tensioner, and reinstalled the belt. Long story short, the puffing sound was my timing belt flapping around due to a failed tensioner. I drove it like this up until about five days ago (~1.5 months). I really had no idea what might be causing it. Onward, to about a month and a half ago, that 'puffing' sound became much louder and always noticeable between 1k and 2k RPM.

I also began to notice what, at the time, seemed to be some sort of puffing sound.

After the trip, my mileage slowly began to drop. Over the summer (~6 months after purchase), I took it on a long trip, mostly highway. I bought this car about a year ago from a shop that had taken it in having had the timing belt break.

Subaru timing belt tensioner