I just noticed a "new" noise coming from my 04 5.4. It seems to only happen when I lift completely off the throttle. It doesn't matter if it is a hard acceleration or a light one.

When I lift my foot off the accelerator pedal I hear a slight ping noise. The only thing I can compare it to is a spring noise. Like the noise a hood spring makes when you thump it, or like the ping you hear when they page someone at the hospital.(Very hard to describe this noise)

I figure it must be some type of solenoid or something. If the truck is above 40 mph I can't hear it due to the road noise. I doubt that it is anything to be worried about, but I am curious to know what it is.

Thanks for any help in advance.
David