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gas mileage = sad face :(

5393 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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I agree with everyone here - the 4.3 is a bit of a pig because it just doesnt have the power to move a vehicle that heavy. Even in 2011, it still only has 195 horsepower and 260 ft.lbs of torque. I also agree that its possible that a change in the gas where you fuel up could cause your recent MPG drop. Also, like enkei said, you might be able to get 1-2 back just by adjusting your programmer a bit, depending on how it is set now.

One more suggestion I have is to clean your Mass Airflow sensor, especially since you have a K&N intake. Over time, the mass airflow sensor can get dirty and cause poor performance and fuel economy. The oil on K&N filters also has a tendency to coat the mass airflow sensor and cause problems with it - particularly if you might have over-oiled it at some point. To clean the sensor, you just need to pick up some mass airflow cleaner (safest to get this because other cleaners could damage the sensor) and give it a good spray. let it dry and then reinstall it.
Not to be a smart ass but 4:10 rear, lift and 33"tires (32.99") and your gas mileage is the same? I would be happy. I don't have any experience with the 4.3 but 15mpg in a full size pick up isn't that bad, but I understand your frustration, I usually average 15-16 in my crew cab (5.3) but that's with a slightly heavy foot, if I work at it I can get 18. But I don't work at it that hard, I drive a truck because I like it!
I have to say I agree on this. I think that with the combination of the 4.3 and the lift and big tires, that's probably about as good as it will get. As to why there was no drop when you lifted it, I have no idea. On my avalanche I seem to be averaging between 15-16 MPG - that with the 5.3 engine, but the 4:10 gears too. On my '01 Silverado I was able to get about 24 MPG on the highway, but that was with a regular cab truck, a performance tune to dial in efficiency, and the 3.42 gears.
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