I have a 2004 Expedition 5.4l and when the weather warms up outside, there is this rattling sound that sounds like its coming from under the car. It only makes that sound with accelerating and stops when I take my foot off the gas pedal. It only makes this sound when its warm out. I do not experience this when in the winter. Does anyone know what can be causing this?

 

Likely spark knock. Try some higher octane gas and see if it goes away.

 

Might wanna try asking the Ford forums too, since its a different make too. Maybe your type uses a different octane level than standard 87.

 

Hey MillBall & 75w90mantraN !! Thanks for taking the time to answer my question. I'll definitely give that a try and let you know!