I have a 2000 F150 5.4 XLT that whistles in the cold mornings. It is loudest at idle. It sounds like it is somewhere on top around the air intake manifold. But it only happens when cold outside. Whe the engine is turned off the whistle sounds like letting the air out of a ballon. The whistle stops when the ambient temperature gets warmer, like over 45 degrees. ANY IDEAS?????

 

There is a TSB adressing that problem. Here ya go. This may be what you have.


TSB 02-10-8 DRIVEABILITY - 5.4L 2V - IDLE-AIR BYPASS FLOW INDUCED WHISTLE
ENGINE - 5.4L 2V - IDLE-AIR BYPASS FLOW INDUCED WHISTLE
NOISE - IDLE-AIR BYPASS FLOW INDUCED WHISTLE - VEHICLES EQUIPPED WITH 5.4L 2V ENGINE ONLY

Publication Date: MAY 20, 2002

FORD: 1999-2002 E SERIES, EXPEDITION, F-150, SUPER DUTY F SERIES

ISSUE:
Some vehicles equipped with the 5.4L 2V engine may exhibit a "whistling" noise from the formed nylon tube in the idle-air bypass flow circuit. This may be caused by air flow passing through the sharp bend radius of the original tube assembly.

ACTION:
Remove and replace formed nylon tube with the Nipple And Hose Assembly 2L1Z-9W548-AA. This action will correct the sharp bend in the tube. Refer to the following Service Procedure for details.

SERVICE PROCEDURE

Replace with Nipple And Hose Assembly with part 2L1Z-9W548-AA.
Connect nipple to the air-inlet zip tube and the free end connects to resonator.
Ensure that there are no kinks in the rubber hose which could restrict air flow.


PART NUMBER PART NAME
2L1Z-9W548-AA Nipple And Hose Assembly