I recently noticed some engine noise when accelerating pretty hard.

I've noticed it the past few weeks with the temp pretty low (30s-40s).

I tested if it were rpm or load/acceleration related...seems like its load/accel related because around 4.5-5.5k rpms under pretty hard acceleration the engine starts sounding noisier then usual and sounds like a really fast vibration.

Same rpms but not accelerating quickly no noise.

To get the basics out the way:
Yes 93 octane.
Yes has oil.
No, I dont thing it is pinging/detonation, doesnt sound like marbles in the engine.

With the colder more dense air the car is probably producing more hp than usually....so I suppose the timing could be causing detonation, but it really doesnt sound like any detonation I have ever heard.

Anyone have any similar experience?

 

i dont know it sounds like rattling, but my car is a beast when it is cold. Definatly sounds meanier when the temperature is below 50 degrees. Since it has been cold down here in Clearwater the last few days ive noticed myself. I would have to hear your car to let you know if it is something abnormal. Honestly though if it isn't affecting your driving then it's probably nothing.

 

The colder it is the more rattles and vibrations you'll hear in any car. If something is seriously wrong take it to the dealer, as it is really hard for anyone to diagnose a vibration over the internet.