Engine makes an intermittent chirping noise that increases in frequency with engine RPM. It comes and goes during driving and is most prevalent in cold weather upon cold start, but is known to occur at other times. I isolated the noise, using a stethoscope, to the rear of the engine near the firewall. The Ford service center has not been able to reproduce the noise in shop but the tech suspected the cam shaft position sensor to be the culprit due to known problems with similar symptoms on Taurus vehicles. The noise in my stethoscope is most pronounced when touching the top of the cam position sensor, so I think this may be a viable diagnosis.
My questions are these: (1) What does this part do? (2) Anyone ever heard of such a problem? (3) Does this part have bearings or moving parts which could cause such a noise if worn? (4) How difficult is it to replace? (5) Anyone know where the removal/install routine is in the factory service manual? I can't find it in mine.
Any help would be appreciated.