I know there are lots of mpg post on this board but this is a BIG difference.

I just bought a 2005 F150 5.4L Lariat 2wd with 35000 miles on it and it is all stock as far as I know. Before this i was leasing an 07 f150 xlt 4wd. On the 07 I was getting 15-16 mpg with mixed driving on my 2005 lariat I am getting 10-11 mpg with mixed driving.

I don't expect miracle mpg from my truck but I also know this is not normal. my brother has almost the same truck except it is a 4wd with 60000 miles and he gets 15 mpg consistently. Logically I should get better mpg with a 2wd.

I have had it 3 weeks and I am about to take it to a ford dealer for a check up what should I ask them to look at or do? What are the variables that can affect mpg this much?

Any suggestions?

Thanks, Justin.

 

Good morning!

Well, if you can rule out any obvious sort of driveline drag ( underinflation, dragging e-brakes, bad wheel bearing, skewed/dragging disc brake pads, etc), then it's possible that you have faulty front O2 sensors. These have been known to go bad in as little as 20k. And if the previous owner used any sort of additive like octane boost, seafoam, etc, it's possible the O2's are now contaminated.

Front O2's control Air/fuels via the PCM - and have a huge impact on mileage if peckered.

Other stuff: air filter, engine cooling fan clutch lockup, winter fuel blends, wrong oil viscosity, tranny slippage, or another bona-fide engine control issue causing overly rich running ...

This is just IMHO, thinking out loud - for starters - there are some good techs here that I'm sure can help. Best wait for their valued input.

Good luck!

Regards
MGD v2.1e

 

Thanks for the reply MGDfan.

Wouldn't the check engine light be on if the o2 sensors are bad? I guess the seller could have cleared warning though.

Will a ford dealer be able to tell if the computer was reprogrammed with a superchip or something and reflash it to factory if it is?

To all:
What are others seeing for MPG on 2wd f150s?

Are the aftermarket addons that I can buy to increase MPG?

Thanks.

 

I have one question. 2005, didnt they have an injector recall for this year? could he have one sticking part open? just a curiousity since the year caught my eye most.

 

Yep, '05 was the problem year for the fuel injectors. I would have them checked straight away as there have been too many locked up motors from those faulty injectors. Plus, if it's injector related they're covered until 100k miles IIRC.

Besides that, O2 sensors are probably the best bet if the truck is running well. They can sometimes go bad and not entirely fail to the point of throwing a check engine.

If its misfiring at all then you might be getting close to the dreaded spark plug change time.

- Erik

 

Just to expand on Scruffy's post regarding the "Dreaded Spark Plug Change"

I've changed my sparkplugs twice with no problems either time. The reason for the-rework is that I changed them before I became a member of the forums and didn't realize the problems that can occur if you do not use Motorcraft Plugs.

I believe I used the Autolite ones and I had one of them burn out on me within maybe 15k miles. So I replaced with Motorcrafts and my truck is running great.

If you decide to change the plugs make sure you use the motorcrafts. Also do not forget to use dielectric grease on the COP Boots to seal from moisture. Further, I would suggest swapping out the COP's at the same time, Global Automotive on ebay sells an 8 pack for right around $115, and they are OEM spec.

Do a little searching on here if you decide to change the plugs, the procedures are here as well as in a TSB if I remember correctly. I followed the suggestions and have had 2 successful plug changes.

If you need any help or have any further questions PM me and I'd be happy to give you some advice!

Good luck on improving the MPG! Let us know how it goes!!!

-M

 

I've always gotten 15-16 with my '05 XLT SCab 5.4 Auto with 3.55 gears.

 

I got 17 running around town and the freeways till I changed wheels and tires and ethanol came to be. I am at about 14.5 now. Screw, 4x2, 3.55 gears.

 

How are you guy's checking your mileage ??

I hope it's the old school way, fill tank and divide miles driven by gallons.

 

another thing that might help you out INSTANTLY is resetting the computer. take the terminals off the battery for at least 10 minutes. i think it just has to be the positive terminal but not sure. the computer adjusts how much fuel it gives you by the monitoring the way you drive. in simple terms, it customizes to the way you drive. it supposedly monitors the last 500miles driven and adjusts. so the guy before you might have lived in a very hilly area and towed a heavy boat so it customized to him working the engine hard and it gave more fuel. if you drive it very easy, it still is customized to his driving and has to customize to yours. it will slowly go up if you go easy on it. but it should be quicker if you reset the computer(not re-flash) with the battery terminal. your mileage should instantly go up from 10 or 11 and then it should customize to your driving instead of still averaging it out from yours + the previous owners. a friend of my dad's, who is very knowledgable about engines, bought a 01 V6 f150 and was getting in the 12mpg range. a friend of his who worked for ford told him to reset the computer with the battery terminals. so he did it and got about 15 or 16 right away. then his driving easy got it up to about 20. hope you get it figured out. definitely something wrong. hopefully it is what i just said.

 

Hello Timothy!

Regretfully,Adaptive is constantly adjusting - there is no set time frame - so a KAM reset will speed up the relearn because it's just tossed out the old data. But over time, it will go back to the same old thing... just the way it works. As well, Adaptive is designed to promote economy and adjust for reasonable sensor aging/drift over time - so it's a good thing, really. But it's not magic.

Escpecially if the front O2's are lazy and/or contaminated. A proper diagnostic tool will confirm if the switchrates & accuracy of these is within spec. Worth a shot.

Good luck!


MGD v4.1

 

asmussen---welcome to the world of Ford gas mileage. I've had my 03 SCREW FX4 Lariat 4x4 for about 6 months now and the BEST tank I've gotten was like 14.9...and that was ALL HIGHWAY!!!! I've been averaging 13.x for the past 4 tankfulls until the last tank....11.7!!! Granted I did have a little bit of 4 wheeling on the beach...so I hope that is why it dropped so bad.
When I did get that 14.9 MPG HIGHWAY mileage I had just cleaned the Throttle body as well as the MAF sensor. Might want to try that. I'm looking at replacing my front O2 soon as well to see if that helps. I have 139K on her and am pretty sure its factory. Hope this helps and please share ANYTHING that you find that help with better MPGs---DirtySCREW

 

i have a 2004 2wd, and lately i was also getting 13.x mpg's and like dirty it dropped to 11.7 and i dunno why. i havent been on the gas or anything like that. i try to keep it at 60 or less. just recently got injectors replaced, spark plug change, i have a K&N drop in, oil and transmission change just done, so lets see what happens. and i also just cleaned the MAF so ill update the new mpg soon.

 

I would ditch that K&N air filter and put a nice clean pleated paper media filter in there. The K&N offers no additional performance and they are known to filter poorly and/or foul the MAF sensor downwind.

 

If you are using winter blend gas with 10% ethanol, there's not much you can do to get good mileage.