I bought the 2005 Expedition new. The day I bought it, I said to the dealer the engine seems noisy, they said...."They are all like that". Which I found to be true. The 2005 5.4 engines were very noisy, sounded like a mild diesel. Expeditions, Navigators, F150 with the 5.4 all sounded the same. I had it to the dealer through an extended warranty period and complained about the engine noise, they claimed it was normal. I changed the VCT solenoids, no change in sound. Finally at 156,00 miles the engine was running rough with misfires and engine light indicating VCT problems. I decided to have the engine rebuilt after much consternation. The engine re-builder told me that the whole top front of the engine had scoring due to lack of oil/lubrication. I changed oil in this engine every 4000 miles and the oil pressure indicator gauge always showed normal engine oil pressure. I contacted a Ford engineer that worked in Dearborn, he checked his sources and confirmed that there was an issue with the VCT timing on the 5.4 with regard to noise, but Ford was not going to recognize it publicly.

The engine re-builder stated he had seen many 5.4's with the same problem. When he rebuilt the engine he used a hi pressure oil pump and upgraded the cam phasers to the Cloyes brand. This engine runs perfect now and sounds normal. Ford would not recognize that there was an issue with this 5.4 engine, I suspect they were betting an engine failure would not occur until after the warranty period.