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LESSON 3: POWERTRAIN
VCT Operation
VCT
The theory of operation for the 5.4L VCT is similar to the 3.9L VCT used on the Lincoln LS and 2004 Ford
F-150 w/5.4L.
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The major differences are:
– The 5.4L VCT system controls both intake and exhaust valve timing because the 3-valve setup uses one
camshaft for both intake and exhaust valves.
– On the 3.9L, the VCT only controls the intake camshafts.
– Parts look different and are serviced differently (5.4L vs. 3.9L).
– Part names are different than those used on the 3.9L.
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The VCT can vary cam timing within a range of 60 degrees of crankshaft rotation.
– Defaults to full advance.
– Requires engine oil at preset temperature before VCT will function.
2005 Expedition/Navigator New Model Technician Training02-SEP-043-12