I'm getting about 15mpg on the highway at between 75-80mph with the truck in my sig. It turns right at 2000rpm at 75mph. I read somewhere that valve lash can have an effect on mileage so I have that on my list. Looking for some other ideas on how to improve it. How much vacuum is normal for the little air filter indicator? My air filter appears clean, but it is registering some resistance.

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Btw the truck is bone stock.

 

i get 13 at 1700rpm's ide love to trade ya. from bone stock to what it is now ,milage changes have been negligable at best, between 1 mpg.

an intake system and a full exhaust will increase air in and out. you could bump the timing up a bit.

 

I get 18-19 on the freeway at 70ish. But I am just over 2,000rpm at 70. Try bumping the timing a bit. That gave me another 2-3 mpg. Changing the fuel filter/fuel water separator on regular intervals will help keep mileage up too.

 

I get 24 unloaded and 21 with 17 ft deckover at 70mph with truck in sig

 

2wd guys make me sad or maybe a bit mad im undicided. 24 unloaded....dick.... LOL

 

I drove to DC from Ohio, got almost 26 right @ 70mph. 2wd is good On the way up I only got 19, but that was putting the hammer down

 

Dont hate on 2wd i get stuck to darn often from sinking on soft grass

 

The biggest thing would be to slow down..My mileage drops exponentially going from 75 to 65 mph. I can still pull 19-20mpg at 75 though.

Gearing is a big difference too...And tire size..3.55 gears will do you a lot better on the highway than the 4.10s will.

Do you have a FP gauge? Low fuel pressure could play a part too.

 

You need to adjust the nut behind the wheel. Or if you see them same mpg's loaded your are over geard.

 

Been there,done that,with my 2wd.

And the gauge on your air filter gauge is just a restriction gauge.It just tells you when the air filter needs changed when the gauge is in the red.Other than that with it,don't worry about the gauge.
I've gotten between 16/18 mpg city driving. And up to 26 mpg freeway. But with the price of diesel here, i try to keep my foot out of it.

And if you want to increase the milage,the motor likes to breathe in and out better.