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gas mileage = sad face :(

5375 Views 29 Replies 13 Participants Last post by  reggiecab2000
If you look in my signature you could see many potential reasons for my poor gas mileage but I swear its the truth that doing every single one of those things has not changed anything in my mileage it has remained the same...
i used to have just the throttle body spacer and cold air intake and flowmaster exhaust with stock tires no lift and still could never hit more than 15 mpg...
even with gears, lift, tires i still have the exact same mileage which usually varies from 13 to 15 mpg, this is a V6 btw...
my last 2 tanks however have been shockingly awful... ive been about 11.5-12 mpg and i dont know why!
i just replaced my fuel filter, i have recently replaced plugs, wires, cap, rotor, oil, oil filter (fully synthetic for years now), sprayed my throttle body, cleaned my k&n filter....
and i still cannot understand why my gas mileage is so poor i also recently seafoamed my gas tank and, a few times a year i am normally throwing in 44K (dads pick)
But i have noticed over the last few months a minimal (noticeable to me) loss in power overtime and i havent seemed to gain it back yet...
I really am going crazy with a 26 gallon tank that i have to refill after 320 miles.... do the math
does anyone have suggestion/help/comments for me?
I am wayyy past my high school gunnin the gas years and hardly ever beat the pedal unless necessary...
but i am fed up with this mileage.
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not upsetting at all i have heard from multiple people and assuming basic physics i agree that smaller engine = more work especially for a full size truck.
i can see how a v8 would not have to work as hard to get the momentum going etc.
but why would this truck be rated 16 city 20 highway if it could never reach it especially if it was stock and had intake exhaust and tb spacer??? (all mpg/power boosters)
and i have heard alot about checking compression? where can i do that though i would not want to do it myself is it cheap to get done? and where at?
as far as tuning my hypertech programmer there isnt much to do its only actual "tune" function is to choose regular or premium fuel, then theres other little things like shifting and top speed limiter etc...
theres not many hills in corpus christi, and as far as rolling resistance im not sure, but my tires have a T speed rating so i would assume there wouldnt be too much resistance for an AT tire to have that high of a speed capability and i have had these tires since december 2008

ill need to look over that ethanol deal yall are talking about and definitely should check out my mass airflow sensor
i cleaned my mass air flow sensor and still not too much difference
also i did find out valero down here is up to 10% ethanol and thats pretty much always where ive always filled up for a while now, time to switch rudys bbq sells ethanol free gas!
also if i started using premium or super gas whatever the higher one is (89 octane to 93 octane) and i also tune my programmer to it, would the extra price of gas be worth any mpg/performance increase?
alright i definitely wont be filling up with valero anymore ill see how that goes hopefully i can pick some mpgs up
do these hypermilers go 35 on the highway too?
so yall think that me goin from 10% ethanol to no ethanol that i should notice a difference in a few tanks?
i am not denying that the lift kit and 4.10 gears isnt affecting my gas mileage i believe you are right all i was saying was that i still have the same gas mileage and even before the lift kit and bigger tires and gears. with CAI, TB spacer, and exhaust with no lift and no aftermarket gears and stock tires i still couldnt get better than 15 mpg usually...
i just didnt see a drop in MPG after the lift and stuff either

also how bad is the 10% ethanol for my truck???
well the only time i get 15 mpg is on the highway when i go home for the weekend to san antonio and ill cruise at 65 all the way from corpus, a good 150 miles. other than that im usually around 13 mpg :(

so is ethanol even good for my engine?
I dont do any of those eco plugs i stick with AC delco like my father taught me too...
and i know my tires are bigger than stock which was (255/75R16) i believe, but then i see 275/60R20 coming stock on most dodge 1500's,and 275/55R20 stock on most new chevy 1500's
so it hardly looks like my tires are bigger than most... but im sure those trucks are designed to work with those tires as well
I dont know my exhaust diameter i went from dual exhaust out the rear to dual turn downs about 6 inches after the muffler about a year ago, and no mileage difference.
How would bigger exhaust be worse? from what i know the faster the exhaust gets out the better your engine breathes. i didnt know there could be a too big?
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