How much improvement should I see in mpg after breakin period on new 5.4L?? I
 

I put 270 miles on my truck in 3 days and filled here then filled her up. After calculating numbers because tank wasn't completley empty when I filled I averaged 14.4 on first tank. Not bad but not good just wondering how many more miles if ANY my truck will get after its broken in?? Thanks

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2001 F-150 5.4L trition,
Regular cab with 8' bed
XLT with Black Clearcoat
4x4 3.55 limited slip
factory cab steps
class III tow package
Factory ordered: 12/5
recieved: 2/22

I'm getting 19 mpg now with my 5.4L. My guess is that you will gain about 2 mpg after break in. You can add a tonneau cover and get another 1 or 2 mpg.

I get less than that almost all the time with about 50% highway driving.

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2000 F150 XLT 4x4 Short Bed. Amazon Green, 5.4L, SuperCab, ORP, Tow Package, Sliding Rear Window, Electronic Shift, Keyless Entry, LT265-70-17 Tires, Clarion Pro Audio, Herculiner Bedliner, Air Silencer Removed.

1994 SVT Mustang Cobra. #1032 of 6009. Black coupe with black leather int., 3.73 rear, Bassani Exhaust, Aluminum D/S, Bridgestone RE-71 255-45-ZR17

My Home Page

Had mine for nearly two years now. I didn't notice a 'break-in' increase. I do notice a summer winter change though.
My driving is 75% highway:
Winter 16.8 mpg
Summer 18.4 mpg
Towing boat (summer,60mph,3400lbs) 14.00 mpg



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1999 Ford F150 Lariat RegCab shortbed 5.4L 3.55LS Towpkg Line-X
15.714@85.21

Increase after break-in? None. The looser the engine gets, the more you're gonna want to stomp on the gas pedal. https://www.f150online.com/f150board/wink.gif

19mpg lucie? holy cow! do you drive strictly downhill? we should swap engines lol

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1998 xlt off road 5.4lsupercab auto pacific green clearcoat power drivers seat, keyless remote with factory alarm, tow package

It is not going to be a night and day difference. Under the same conditions, slightly better.

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My Ride: 1998 F150 4x4 Lariat Supercab Flareside 5.4L in Oxford White/gold, ORP, Tow Package, 3.55 Gears.

Modifications:
Optima Red Top Battery
Split Fire Spark Plugs
K&N FIPK
Gibson Supertruck Exhaust System
Stepshield door sill protectors
Performance Accesories 3" Body Lift
Superlift 3" lift blocks
Performance Lift Lips
Gabriel Gas Ryder LT VST Shocks
Daystar Front Anti-sway Bar Polyurethane Bushings
Heckethorn Steering Stabilizer
35x12.5R16.5LT BFG All Terrain KO's
16.5x9.75 American Eagle 589's.
McGard Premium Wheel Locks

Photos at: http://www.communicomgroup.com/jmtruck

Almost all my driving (90%) is highway (not interstate) with speeds of about 50-60 miles per hour. That's probably why my mileage is so good. I don't hot-rod very much, either.

Yeah ill be doing alot of highway from work and back. I havent done much highway yet so maybe thats why Im getting 14.4. Im so glad I opted for the 5.4L. The salesman I had tried to sell me a used 4.6L with 30,000 miles and I almost got it because I didn't want to wait the time for factory ordered. IT was well worth the wait. Never felt so much power in my life. I love my truck https://www.f150online.com/f150board/smile.gif

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2001 F-150 5.4L trition,
Regular cab with 8' bed
XLT with Black Clearcoat
4x4 3.55 limited slip
factory cab steps
class III tow package
Factory ordered: 12/5
recieved: 2/22

Mine is pretty consistent at 14 city/17 highway. It was getting 10 combo when new.

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2000 F-150 XL, RC, LB, 5.4L, 4R70W, 3.55LS,
Class III tow, Payload #3, & Convenience pkgs.,
4-wheel disc/ABS, Chestnut/Parchment 40/60,
Ford bedliner w/Paintsaver & gas/wheel/spare locks,
K&N F.I.P.K. w/Outwears pre-filter, Superchip,
Dynomax ultra-flow welded 3" cat-back w/ 3" Y-pipe,
Hellwig front & rear anti-sway bars, Rancho RS 9000s,
Mobil 1, K&N oil filter.

there is no break in period
period ........

Strictly speaking, that's true, but it doesn't explain why most of us notice or trucks getting better mileage after 2 or 3k miles.

ok hotshot trying to be smart fordtech. I was told by dealer to drive at different rpms so engine is broken in at all different speeds rather than consistently driving at one speed.... period.

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2001 F-150 5.4L trition,
Regular cab with 8' bed
XLT with Black Clearcoat
4x4 3.55 limited slip
factory cab steps
class III tow package
Factory ordered: 12/5
recieved: 2/22

and if he said to drive off a cliff would ya

my milage has been pretty consistant.
13-14 in town, 14-17 hwy.
got 13 after spending a whole weekend in 4HI.
The most power in my life, my 5.0 w/ 2.73 gears would spin the rears effortlessly.
I've drove plenty of 7k lb PSD that have 500ftlbs stock. I've really never been impressed w/ this motor. It does fine, better than the 4.6, but 333 ci for 4630lbs really isn't enough motor IMHO. I have thought of going to 3.73's or even 4.10, to have some more low end.
To each his own.

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Dr.(wife says i'm spoiled) Jones.
2000 F-150 5.4L
AUTO,SC-sb 4x4-XLT, 3.55LS, 8.8 front- 9.75 rear, sidesteps, sprayed in liner, 17"wheels ORP, trailer-tow pkg, CD, Cpt chairs, 4whl ABS, Keyless Entry, Airbox silencer removed/K&N, Amsoil(transfercase, motor, rearend(with no friction modifer AND IT WORKS GREAT NOW ), 3" custom dynomax ultra flow catback, as an anniversary gift. With a best of 18.5 MPG.
kjones02@elp.rr.com, strengthbeyondstrength2000@yahoo.com waiting for the 275hp PSD
www.ford-diesel.com , www.fordvschevy.com/ , www.blueovalnews.com/, www.webattack.com, www.thedieselpage.com/cgi-bin/Ultimate.cgi

Dave i have a 2001 expedition with the 5.4 and 3.55 axle. I was getting 13 mpg.(with 500 miles) before i put a three inch exhaust from the y-pipe back and put in a K&N oem filter. I did these mods and my next tank of gas i was averaging 15.5 mpg and that was pretty constant till we got about 1500 miles. We now have about 2100 miles and we just made aroad trip to Dallas to see my inlaws and we got 408 miles on one tank of gas before the low fuel light came on. Filled it up an we averaged 18.6 running 74mph interstate and the last 60 miles on the tank my father-in-law and i wee seeing what kind of power it had, a little hot rodding.
In my opinion yes you will get better milege after the engine is broke in and all the rings are seated. And yes you are to vary engine rpm over the first 1'000 miles and i did exactly as the MANUAL said. Never hot rodded it till after the 1,000 miles.
We are averaging about 15 to 16 city if we drive easy and 19 or better on the hwy. rom the posts i have read i feel fortunate tobe getting that kind of mileage.
The best thing you can do for your mileage is to NOT gun it all over town and try to maintain constant speeds as much as possible. And when you get ready to have some fun just know that your mileage will suffer. Good luck!

Hey thanks 01x for the advice. Sounds like you are getting good gas milelage with your 5.4L. I absoultey love my truck. Never could be happier. Also I would like to add I think the Expeditions are the sharpiest suv out there and if I didn't get a truck I would of got Exp, very cool looking just like F-150 https://www.f150online.com/f150board/smile.gif

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2001 F-150 5.4L trition,
Regular cab with 8' bed
XLT with Black Clearcoat
4x4 3.55 limited slip
factory cab steps
class III tow package
Factory ordered: 12/5
recieved: 2/22

I've been getting around 13-15 mph my 1st winter with my 5.4. About 70% highway and 10% 4wd. I'm going to add a tonnaeu cover and see if the mph improves this summer. I really like the low end torque of this engine while towing!!

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00' F-150 XLT 4X4, SC, SB, AT, 5.4, 3.55, Tow pkg, DuraLiner,
Westin platnium bars, , Chestnut Brown/Beige