One problem related to manifold/header/muffler/tail pipe has been reported for the 2005 Ford Expedition. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Ford Expedition based on all problems reported for the 2005 Expedition.
Recurring engine noise which is more noticeable during cold weather. Under load the engine , particularly at 2000 rpm, sounds like there is a manifold leak or a valve ticking. I have been to my dealer twice(out of business) and two other dealers three times with no satisfactory results.