Just here to share my experience in hopes it will help somebody. I have a 2014 Trail edition with 60k. It started making an unusual whining noise that was very noticeable during acceleration a couple thousand miles ago. I removed the belt and briefly ran engine before taking to dealer in hopes it was an accessory or idler pulley making noise. Noise was internal. The dealer confirmed noise was not normal. The technician disconnected transmission from engine to isolate the noise and found that it was coming from the engine. After discussing with Toyota field tech that just happened to be on site that day they removed driver side valve cover and reset the timing chain tensioner on that side. Noise went away but returned after several minutes. At this point they removed the engine and replaced the timing chain, tensioner and guides under warranty. It has been about 500 miles since the repair and I’m very happy to say that the very annoying whining noise is gone.