2004 F140 5.4 i have 83k on the OD. I dont recall seeing anything in the maint. guide about plugs. When is a good time to change them?

 

Ford originally said 100,000, then they came back and revised it to 65,000. If it is running good, not losing any mpg, I would go to about 95,000. I did mine at 65,000 and they were still fine. I pan on going to about 95,000 on this second set.

 

Hey Bluejay is that 65000 recomendation new. I'm almost at 65000 and not really looking forward at getting my plugs changed.

 

Well, I have an 04 XLT 5.4L and 82k on the odometer. Did my own plug change and broke 7 of eight. I would change them, but get you the lisle 65600 tool incase you break one, it works well. Good luck

 

Find someone else to do them!! I just did passenger side and it took 2 hours. There is too much stuff in the way.

 

I don't recall for sure when it was first out, but I think it was possibly part of the last TSB for removing the plugs.

 

My 1998 expedition has 166,000 miles and runs fine . With all the problems changing plugs I plan to change plugs soon but only if my fuel mileage falls off or it looses power.Some times preventitive maintenance does not pay especilly with this plug design.

 

166 miles on the original plugs? Wow.. The plugs in that engine are really not that hard to change and theres really no issues with them. Its the 04-08 engines. All you gotta do with your engine is torque to 28 lbs no anti seize..

 

Are the Ford Motorcraft plugs good or or should other brands be used for the replacements?
Thanks

 

Use the Motorcrafts.

 

My 2005 has 140k miles on the 5.4, and it's lost about 1-2 mpg total...I usually average over 20mpg highway and 16 in town, but it's now around 18/15. I'm not ecstatic about changing them myself, but don't really care to pay the stealership $300 to change them either.

I'm more of the convention that I'll drive it until one fouls and then change them, versus trying to change plugs that are still good and breaking one or more...I just feel that Ford should subsidize some of the expense to change them since it is their design flaw, whether it's a redesign Motorcraft plug or discounted service visit to change them, etc.

 

I did my '05 5.4 l this weekend @100k.

Plug gaps were about 50% more than spec. They were OK for fouling, etc.

In my Saab mechanic days, the Saab coil over plug assembly was famous for failing when the plug gaps got large**. So changing sooner rather than later may help save a coil or two IMHO.

I'll do the next set in 65K, and do my '07 4.6 liter this month (70 k)

**(takes much more voltage in the secondary to overcome the dielectric strength of a larger gap. big secondary voltage burns through the epoxy in the coil)