MyOtherCarIsAPlane

I have a 2005 F150 screw with the 5.4 V8. I have an interesting exhaust rattle, that only occurs when the engine is slowing down. The easiest way for me to reproduce the rattle is:
1. Start the truck.
2. Transmission -> Neutral
3. Floor it, wait for engine to redline.
4. I take my foot completely off the gas, the engine slows down, and I get a tinkling rattle from underneath the truck.
The rattle sounds like someone put some loose change in a soda can, and shook it around. I haven't yet had a chance to have someone else sit in the truck while I stick my head underneath.

Does anyone know what's causing this sound/how I can fix it? It gets quite annoying, and is audible even at lower RPMs.
Thanks in advance for any help!

04whitefx4

Look to see if any of the hangers are broke

techrep

iTrader: (1)

Heat shield on your Cat could be loose.

Masi1926

I've had a rattle at just above idle for years. Definitely one the cats, I've checked everything. Has to be inside one of them.

rammer24

I've heard a loose manifold can cause this. I could be wrong but I'm sure I've heard that from someone. Worth checking out.

techrep

iTrader: (1)

If the Manifold was loose, don't you think he would hear an exhaust leak instead of a rattle ??

Masi1926

Let me know if you do figure it out tho. I'm going to have my cats replaced with new ones soon, so if that fixes it I'll get back to you.

MyOtherCarIsAPlane

I don't think it's an exhaust leak, I haven't smelled anything. I'll look under there later today and see if I find anything.

I'm also close to my 30000 mile service, so I'll have them look at it then if I can't find anything.

Masi1926

Also I'm on my 2nd set of duals, so its definitely cat forward. It sounds like a heat shield rattling but its not. Most aggravating.