zap

4.2's never had a COPs set up right?

Hollabakzach23

I don't believe the 4.2s have cops but then again I could be wrong??

zap

Mine doesn't but I was giving some leeway since I have an 02 and the Essex plant didn't close until 08, so there may have been a later model but I haven't heard of it.

thetruck

I Do thing something is wrong, I have a 4.2 supercab manual w/lift and 285/75/16 and getting on average of 17-18 during winter and during summer 18-19 (approx 80% highway). (not loaded) Have you tried the stealership for a diagnostics? sometimes its cheaper just to let them find the problem and then you can fix it.

Javi_F-150

Did the CEL throw out any codes?

yossarian

Thanks everyone for all of the ideas.

Yeah, I used to get 17-18 mpg so I'm sure something is wrong.

The CEL put out a few codes. The first two were for the O2 sensors. I replaced them and it didn't really do anything. The other code indicated there was some kind of an exhaust leak. Had the garage hook it up to a smoke machine and they couldn't find anything. Not sure what to do now.

blueovelboy

it has 102k it might need a tune up! i mean the motors are spoused go 100k be twine plugs and wires or fuel filters and i am guessing

Warspite

I have the 4.6, and ONCE got 18.5 MPG highway (averaging 70-80 MPH from Miami to Atlanta). My combined is only 12-13 MPG, at 135K miles. Cold Air intake was installed 100K ago, so there was no gain in MPG. Stock tires/sizes, no engine "snake oil," and the bed is usually empty. No codes or CEL. Time for new wheel bearings (fronts are shot), so anything that adds resistance will hurt MPGs (fan clutch, wheel bearings, underinflated tires, closed tailgate, etc). I have a tailgate toolbox (screwed on), or I would have considered taking off the tailgate and put the net on. Remember, when the '98 was produced, gas wasn't even $2 per gallon!

5.8 Lover

Yall think u have bad mph??😂
I drive my dad's 02 expedition with a 4.6 v8 sometimes and I'm 16 I can average 4.5 mpg if I drive like a dumbass😂

02_Black_On_White

Lol closed tailgate...