Engine noise upon acceleration

[Peaches57]

I just noticed sort of a "flapping" noise (maybe it's engine knocking?) when I really accelerate hard in my 2008 EX. Only happens when I really gun it, like to go up a long, straight highway entrance ramp. Once I am already zooming along, there's no unusual sound.

Has this happened to anyone? Could it be bad gasoline? The first time I noticed it, I had just filled up the tank in an out-of-state gas station. I don't really get the chance to hit the accelerator quite like that very often (live in CT where the roads are congested, short and bumpy!)

Any ideas? Thanks!

[EXceptional]

Is this still happening ?

[Peaches57]

I'm not sure if it's still happening (the car has been garaged during this rainy week). I don't often get the chance to really floor it ... that is when it seems to make the sound.

Just wasn't sure if that's what engine knocking means, and if it's due to the gasoline, does it get better once you've used up that tank?

Thanks!