GreenTitan05

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

techrep

iTrader: (1)

Depends when the plugs were changed prior to you owning it...if ever...any Maintenance history ?? they were due @ 100K for sure

GreenTitan05

Yea I know they were due then I was just trying to postpone when I can't work during school and I don't think they ever were though.

Fordfan2006

motorcraft plugs and if you aren't too good with DIY stuff don't do them they break off.

TSR6

This is my project today on my 2010. Mileage has dropped from 16 or so, down to 14.5-15 (and i make the same exact drive every day) - I'm at 110,000mi with zero plug changes yet (all my miles)

...planning on starting today's project within the next hour.

GreenTitan05

Let me know how it goes and thanks for the help guys

Adam013085

Id be happy to squeeze 14.5-15 out of my 4.6 in the winter time.... But yes, Id change the plugs if I were you. I plan on doing mine once the weather warms up and I am at about 62k miles.

aviationmech2004

just had mine done at 99,000 miles, two days and 6 broken plugs later it runs like a dream.

Adam013085

nice looking truck

azjay72

did mine also..no change in mpg..but no more studdering..runs great now..did mine at 81k..also my check engine light is off and it passed emissions!