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gas mileage = sad face :(

5391 Views 29 Replies 13 Participants Last post by  reggiecab2000, 
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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Big tires and lift kit are hurting your economy.

tbplus10 said:
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The short explanation of the task is remove the first spark plug, put in the compression testor adaptor, neutralize all the other spark plugs so the engine wont actually start, have someone turn the engine over while you record the readings on the compression testor gauge, then proceed to the next cylinder, repeat the proceedure until you've got a reading for every cylinder, compare the readings you have with the manual and see if you have any exceptionally low cylinders.
Click to expand...
When doing a compression test -

Remove all spark plugs. Hold the butterfly wide open. Pull the ECM fuse. Then do the test as described above. You need the butterfly open to get plenty of air in the cylinders. You also reduce load on the starter/battery because you're not pulling any vacuum. That's also why you pull all the plugs first.
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If the truck is driven regularly it won't be affected. As long as the fuel is turned over every month or so you shouldn't have any trouble. If you only drive occasionally, I would use an ethanol stabilizer and/or Seafoam.
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