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gas mileage = sad face :(

5378 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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Like Avalanche says- if your station suddenly went from pure gasoline to Gasohol- up to 15% alcohol- your mpg could drop 1-2 mpg easily.
Check the pump at the station -see what it says.
Like TB implies- the 5.3 is hard to beat-the 4.3 and 4.8 usually can do no better than match it- and usually fall a bit short of the 5.3 in respect to mpg.
PS But the sudden drop makes me think ethanol in gas- or you switched stations to one that has ethanol.
I hypermile my 1998 Suburban-when just I drive it- I get about 15 mpg city 21 mpg hy.
Wife however gets maybe 10 mpg city.
Many folks do hypermiling "lite" with 1/2 ton and even 3/4 ton trucks.
Mild hypermiling can improve your city mpg by 15-20%- it is basically just accelerating up to 35 mph-lifting off the gas and cruising down to 28mph- repeat repeat.
The GM truck transmissions GLIDE (ONCE YOU LIFT OFF THE GAS) in D just like they were in N.
1/2 Trucks and SUVs respond great to hypermiling- you save a lot more gas -and $$- hypermiling a 1/2 ton than you do hypermiling a Prius.
35 hy- nah, I set my CC to65-68mph in 70 75 mph zones- but 58 mph in 60-65mph zones. I get 21 mpg on long trips, but that is because of all the 45mph road work zones and towns where you have to drop to 35mph or so.I would get about 19.5-20 mpg at a steady 65mph.
Our V-8s probably get best mpg at about 50 mph or so- just above where the converter locks up.
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