Hey everyone, I have a strange noise comming from my 07 Endeavor, which only happens under acceleration. This sound cannot be replicated in the driveway...Only while driving and only while accelerating. I've had a few friends ride with me and they say exhaust leak.

When your driving along, and if you step on the gas, and the RPMS jump above 3000, you hear a sound comming from under the car that sounds like "flapping" as the vehicle speed and RPM increase the noise gets louder. Once the car shifts and the RPMS drop, the sound magically goes away. I used the auto stick to down shift and make the RPMS increase as the vehicle slowed, but this did not produce the sound. Only while accelerating, and if I really mash the gas, the sound gets louder.

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Here is a link to a video I made while driving, you will hear the sound during 2 accelerations, one down shift does not. My son makes some noise too, but you can tell what that is. Engine light is on telling me I have catalyst issues with my O2 sensors. Not sure if they are related to this "exhaust leak" or not.

Its not a heat sheild, I know what a heat sheild sounds like. This is a Fluttering noise.