acer

i have a 2006 f-150 fx4 crew cab with 5.4 auto. Produces strange noise at 2500 rpm in any gear under heavy load up hill or when towing? Any one else experience this? sound like it is coming from under my feet or in the exhaust?

ravn

Yes, I am experiencing something similar. 2007 f-150, 5.4 auto, I don't see it here at home in flatland Illinois, but in hilly areas such as PA and KY it comes out. Going uphill with speed control engaged, it sounds kinda tinny like a heat shield or the exhaust? As you said right under my feet. Muffler guy beat all around the pipes found nohing loose. We tried a glass pack thinking the resonate frequency may be causing something, no it didnt change. I have an edge programer, going back to stock tune lessened the vib. noticeably.

sfdude

Does the noise sound like a moan, groan, or honk? If so it is probably resonance in the exhaust. Ford has a vibration damper (basically a steel cylinder made onto a muffler clamp) that you bolt to your exhaust pipe. Mine did that at 2,000 rpm's no matter how you were driving. Had to experiment with different placements (moving it a couple of inches matters) until I found the right spot.

Once I did, problem solved.

Mark Matteson

Did you every figure out what the noise was? Mine is doing the same thing.