Re: 2004 F150 5.4
Peck...as in a tick noise?
What's the mileage?
You may be experiencing engine knock, which can be disastrous over prolonged periods. I'd get a tune up done, with new plugs for sure. If the noise rises with engine speed then it could be a valve train problem. As a test for pre-detonation try running ten gallons of 91 octane once your desperate for fuel, this is providing you currently run regular (87octane or lower). The higher octane burns differently but a good tune up can also correct any timing issue you may have.
'11 Ram Quad Cab 4x4 SXT 5.7L HEMI (stock); 48,500m
'06 Pontiac G6 GT 3.5L 220hp; 64,000m
'12 Chrysler 200 Limited 3.6L 283hp; 28,000m
'99 Taurus 3.0L 2V Vulcan 145hp; 154,300m - Traded
Amsoil in all vehicles!