I asked for help on this one as well. Not a lot of responses. It seems that most of the replies are either engineers rambling on about formulas and scientific theories or people who are not real comfortable working on their own vehicles. Maybe buy a service manual or ask a mechanic.

 

I have a 97 Expedition with 70,000 miles on it. I want to change the plugs but it looks like it might be a nightmare. Anyone changed the plugs on a 5.4 yet? Any tips or tricks to changing them? Thanks.