Some 2005-2012 Lincoln Navigator vehicles equipped with a 5.4L 3V engine may exhibit an intermittent rattle noise and rough idle when the engine is at operating temperature. The cause is oscillating cam timing. DTC P0022, P0021, P0340 and/or P0341 may be stored in the PCM.
1. Using the Integrated Diagnostic System (IDS) scan tool or equivalent, monitor cam solenoid duty cycle and cylinder head temperature (CHT) parameter identification (PIDs). Start IDS, select Data Logger, and select PIDs VCTDC, VCTDC2 and CHT.
2. With the engine idling at normal operating temperature (CHT above 200 degrees Fahrenheit), apply the parking brake and hold the service brake pedal firmly with the transmission selector lever in D. Raise engine rpm from idle to about 1500 RPM and release the throttle. Does the vehicle exhibit a rattle type noise with a rough idle and are the cam solenoid duty cycle PID values oscillating after RPMs return to idle speed? If yes, proceed to Step 3. If not, continue with normal diagnostics.
3. Replace both the left and right variable camshaft timing (VCT) oil control solenoids (P/N 8L3Z-6M280-B). Also plan to replace the cam cover gaskets. For 2005-2006 models, also replace the VCT solenoid to cam cover gasket P/N 3L3Z-6C535-AA.