A few months ago, my 2005 Lariat developed a noise that originated from an area to the left of the driver's side footwell. On acceleration from a stop, I would hear what sounded like a ribbed wiring harness grating over a metal or plastic edge. The noise would last anywhere from a 1/2 second to a full second, depending rate of acceleration and how cold it was. This noise would disappear when temps were over the 60's, but was very pronounced when it was in the 30's and 40's. This was aggravating because I could only diagnose it when it was cold.

Here's what I found after checking everything else: I removed the left front wheel, then the inner wheel well liner.

Between the driver's side footwell and the fender wall, there is a foam rubber piece that occupies the space.


I found that this piece had split in two, such that one piece was basically just flopping around inside. The noise I had been hearing was this piece rubbing against the metal body - and of course when it is colder, rubber gets stiffer, thus aggravating it....and when it is warmer, the rubber is softer and makes little or no noise.

I glued the pieces back together and fit it in nice and snug.

Don't know if anyone else is chasing a similar problem, but I hope I can save someone some trouble in finding the cause.

 

I have a similar sound coming from the same side and with the same conditions, Found that mine is most likely the gotts mod plastic rubbing the metal. I push it in tighter and it goes away. If it happens again may have to look into this. Thanks for the post.