My 2002 (5.4 with 12,000 miles) makes a quiet (barely noticeable) clicking/knocking noise that I only hear when I'm stopped. I presume this is because it gets drowned out when I'm moving. It is a very fast (about 3 times/second) clicking that I thought was the fan. It wasn't. It seems to happen only when the engine is warm. It quiets down, but doesn't stop, when I put her in park. It sounds like it is coming from behind the radio, but I'm just not sure. I left it running and popped the hood, but couldn't find it. It seemingly has not affected performance in any way. Has anyone had an experience similar to mine? Thanks!

John

 

Probably the cooling fan that FORD installed on top of their cheap-as$ stereo. I traced it back to that on my 02 SCrew.

 

Pop your hood and take a listen. Sounds like you are hearing your fuel injectors....