I have a 2005 5.4L Lariat and when I bought it in June 2013 it had a little over 100k on it. Since then I've put 13k on it so I've gotten a good feeling for how my truck drives. Usually when I drive on the highway it gets up to 15 MPG and when I drive around school it'll usually drop and hover around the 14.4 MPG range. The past couple of weeks though its been shifting late and it's dropped to 13.7 in about a week. Since I've had it its never dropped this low before and I haven't changed my driving habits or commute. Is it time to change the spark plugs and if so what's a good brand and place to get them? Thanks for the advice

 

Hi.

Yep - change them now.

Motorcraft SP515, from www.rockauto.com

Check our How-to articles section for R&R procedures.

However, it's also possible that you have other issues / maintenance to perform. List here:

https://www.f150online.com/forums/5066174-post2.html

Good luck


MGD

 

Just did some research, another guy is having the same problem and is doing his spark plugs today. Probably have to do it as well.

 

If you bought it new, and it only had 5,000 miles on it, it is still strongly recommended to change them out and replace with the updated SP-515 version.

Your mpg stats are similar to mine with 33"s. Now that we are running winter blend fuel, and I have 34.5" tires, i'm down to around 12mpg. Shortly after I broke 100k miles my engine lost its 'feather light peddle power' also, sign of worn plugs.

 

Ok I'll probably end up doing it, just to be sure there wouldn't be any other problem that would cause this would it? Also what's a reasonable quote for the 5.4 change if I bring my own plugs?

 

I'd be interested in getting some input as well, need to change my plugs soon I think and I def don't have the know how nor am I handy enough to undertake it myself.

 

Shooter - what kind of engine do you have? The 5.4l is a very difficult one in terms of spark plug changes but here's a link on the How to for it: http://www.f150forum.com/f72/how-spa...-3v-v8-116291/
If you don't have the 5.4 this gives you at least an idea of how to do it or try the search bar for how to do it.

 

I have an '08 5.4L as well. Been doing a good amt of reading since I joined the board here and pretty soon will be calling around my local dealerships for some quotes.

 

If you have brown COP boots instead of black, you have the 2008 mid year redesigned heads. Good to know when getting quotes as its just a straight forward plug change, no breaking risk.

 

Hi.

Much easier to see the number on the top of the COP after wiping all of the crap off first, lol.

If it's COP number 8L3E, you have the revised heads and 1-piece 12mm spark plugs. ( With thanks to Ross-FX4 for providing this information )

Which will make the job relative cake with no breakage concerns. Plugs are cheaper too.

Good luck
MGD

 

Regarding them being black vs brown, we talking about the plug itself or the boot?

http://www.supermotors.net/getfile/6...lsize/cop1.jpg

 

That would be the boot.

MGD

 

Bummer, mine are definitely black, not brown =/

Ever see this method of removing the plugs? apparently a lot of ppl have had success with it even though it's kinda scary...

 

Several members on this site have used that method. Successfully for the most part.

 

Hi.

This is no longer a pucker-factor exercise if you do the research and have the proper tools and supplies at hand.

Yes - impact method has been discussed many times here - we have a few folks who have done same with good success.

I use hand tools - again, no issues to-date.

There are also reports of folks breaking plugs regardless of method used.

good luck.
MGD