2006 f150 5.4l.
 

Sounds like a diesel while idleing. When I bring it up to about 800 rpm it makes a ticking noise. Got it 4 days ago from a dealership, under warranty only covers what is required for state inspection.other than that it runs perfectly fine.

Just in case it is an exhaust leak at one of the exhaust manifolds, it should fail any state inspection. If you can determine where the sound is loudest then pinpoint the area , that might help isolate the problem.

Sounded like it was coming from the engine