October 16, 2006
Does it quiet down when engine is fully warmed up? If so, it might be the oil, and I'd suggest changing to Mobil 1 synthetic.
It might be this tech service bulletion:
09-007-04 03/02/2004 Engine & Engine Cooling:Engine -
Irregular Engine Snapping Sound
OVERVIEW: This bulletin involves chamfering the bore
radius on cam bearing caps L2 through L5 and R2 through R5.
NOTE: This bulletin applies to vehicles equipped with a
2.0L, 2.4L DOHC, or 2.4L Turbo engine (sales code ECC,
EDZ, ED1, EDV, ED2, or EDT).
SYMPTOM/CONDITION: The sound may be noticed when the
engine is idling in park between idle rpm and 1400 rpm at
normal operating temperature. The sound is on the upper
end of the engine (cylinder head) towards the front of the
engine or passenger side (right side). The sound is
irregular, not periodic or harmonious. The frequency of
the sound will increase with RPM. The sound is more of a
higher pitch snapping noise, not a low metallic knock.