with a k&n fipk, tb spacer, e-fan, and flowmaster 40 on my 4.6 (15,000 miles) i only get 9.5mpg. WHATS WRONG WITH MY TRUCK??? before i freed up the intake i was only getting 11mpg. would a programmer help my engine recognize the changes to increase the mpg (no CEL has illum)?

 

Find someone with a true scanner [not a code reader]that knows what they are looking at and pay for a diagnostics. Could be that your computer needs a new flash.

 

Clean your MAF sensor. Those oiled filters have a habbit of taking a dump on them. If your mileage doesn't improve, take the intake off, and see if it fixes it.

 

after just ordering my XCAL2 i asked the techs at troyer why i lost fuel mileage...i have been running E85 (89 octane) since i got the truck in november. ill switch back to petroleum fuel (87 octane) immediately!

 

seems a little low for those mods. The TB spacer will actually hurt you a little, but expect some mileage loss during the winter months, when you use winter formulated gas,

I usually average 12.5-13 in the city, and usually see 17+ on the highway
-Patrick

 

You can't run E85 in a 2003! And E85 is 105+ octane! There's no way you've been running that, and not noticed it!

 

the pumps say E85 for midgrade. i dont think the rating system would be different here in nebraska...

 

okay...its E10 here in nebraska. sorry for the misinfo. either way i guess im fully back on the tit of opec

 

I get about the same on highway less in city but thats my own fault.I have 5.4 w/ 3.55 gears on stock tires

 

Did you try my suggestions?

 

Yeah, I'm sorta in the same boat. '99 SCAB, 5.4, 4x4, 3.73's, and stock size tires. I have removed the silencer from my stock intake, have a K&N drop-in filter, and removed part of the airbox (where it connects to the inner fender). I have a Flowmaster catback SIDO system as well.
I don't really drive that hard most of the time and I only get around 11 MPG driving around here. I guess you'd call it city driving. I live in a pretty rural area and drive a lot of country roads, mixed with light city driving. I don't use my truck much on the highway, but seriously, I'd think I would get better than 11 MPG. Am I expecting too much?
At any rate, if there's something I can do (besides the obligatory lesson on driving really really reaaaalllllly easy) to get a few more MPG's I'm willing to try. I was thin king about eliminating the EGR and the PCV valve. Also considered seafoaming the thing, but it has less than 60,000 miles on it, so I wouldn't think it's too fouled up. Any ideas?--DIY

 

What is the reasoning behind better mileage in the summer?

 

I believe it is the "winter blend" fuel. No solid answers on why, but I get from 2-5 mpg worse in the winter, even though I drive ALOT more conservatively in the winter (Alaska roads=ice)

Summer=15-16mpg hwy
Winter=9-12 mpg hwy

Also, on my last trip from the lower 48, I got the worst mileage in the plains states. I just got what I thought was the regular gas, and everyone says I couldn't have gotten E85 or high ethanol gas without knowing it, but nevertheless, the worst mileage I got was in the midwest/plains.

 

I also believe that the winter blend has something to do with gas mileage as mine also drops to about 14.4 after the blend goes into the tank. I usually get 15 .4 with my 2004 5.4 3V with 3.73 4X4 and I actually hope to increase that with a tuner and low restrictive exhaust. My truck is mostly stock now but I have been calculating the cost for the mods versus the saving at the pump and how long it will take for the mods to pay for themselves with gas expected to hit the $3 range this summer…

Do clean the MAF sensor but be very careful while cleaning. I read a how to on one of the web sites I surf and they are a sensitive item.

Do let us know when you find a cure...

 

Been tracking my MPG for about 9 stops at the gas station. I average
11.73. Which stinks...