Flutter noise in RAV4

Hello,
I have a 2011 RAV4 with 122,000 miles. For the last few months I have heard a fluttering noise coming from the engine compartment, usually at in-town speeds when I step on the accelerator gently, for example to maintain speed on an incline.
What could this be?
Thank you very much.

Any of 1000 things.
Pop the hood, have a friend gently push the accelerator pedal, and see if you can hear anything. If you do, try to determine where it’s coming from.

Unfortunately, today’s cars contain countless plastic shrouds, splash panels, clips, and other parts that can cause a fluttering noise at resonant frequencies. I’ve fixed a fluttering noise by securing the plastic splash panels under a car. Wheel well liners are another common source. Sometimes you just have to search.

Also, if it’s been getting colder where you are, that contributes to the tendency of plastic panels to flutter as they contract and their fit changes.

NOTE: if you’re also having any operating problems, or have a fault code, please add that to your post.

By chance have you ever noticed a flickering oil light?

I have a 2009 Rav4, and it makes quite a few peculiar noises. One I figured out was a weird fluttering sound from the electric power steering. It’s been there since new, and the sound hasn’t changed. Another one I swear sounds like a bad or out-of-round tire. Every test I’ve thrown at it says they are fine, but the sound persists even after a tire rotation and alignment. This sound has also not changed since I got it. So, I live with it.