Got a question...
On my 2000 F150 5.4L, ive had the familiar broken stud/leaking exhasut manifold situation for about a year now, pure lazyness is the only reason I havent fixed it yet (got parts, plan on doing it tomorrow)

My question is this:
I talked with a guy at the dealer where I got the parts at and he said a common comlaint along with the leaking exhaust is poor fuel economy. He said air gets sucked into the exhaust and the O2 sensor sees this as a lean condition so it richens the fuel mixture up. Is he full of BS or is he telling the truth. Any techs at Ford dealers came across this issue?

Thanks
Jason

 

Its possible but not probable.Usally when leaving a exhaust leak at the manifold can ruin a aluminum head.Hot exhaust gases can cut their way through aluminum in no time at all.Never wait to fix this kind of thing.Also can warp the manifold itself.
Rich

 

They generally only suck in air when decellerating not accelerating which can also burn exhaust valves over time.