Gas mileage!!!!

[19-Silverado-98]

Ok I'm can't find anything that's helping me. My truck is getting 11mpg. My question is why. It's a 98 chevy1500 4x4. 5.7 auto. I've done a tune up. Replaced fuel filter. I've put a throttle body spacer on it. I've capped the silencer on the air box. It has 3.42. 2 in lift. Or leveling kit. And 265/75r16 on it. I've hear people are getting 16. And some are not stock. But I can't figure out why mine doesn't. It's killing me. Anyone know anything?

 

[jmc1997ck]

How are you doing the calculation of your mileage? Obviously, check the staples... Tire pressure, alignment, drag on engine peripherals, how hard you accelerate on average. I'm not the most knowledgeable, but maybe check fuel pressure and fuel return line (if these trucks have them) to see if everything is to spec and there are no leaks. Do you live in an area where **** head kids are siphoning your gas? I get about 16+ in my '97 RCSB 2wd with a 5.7. All stock except for Airaid intake. Wish I had a few magical tricks to share with you to bump up those mpg's.

 

[Old Goat Ninja]

Yeah, sounds wrong. Something is up. Last trip to my dads cabin, it was almost all uphill, and I had to floor it most of the way just to barely maintain a steady legal speed, and I have 35's, and I still got 10mpg on trip up there. So 11mpg just driving around sounds bad. I don't check mine often though because I rarely fill it. It's not my Daily Driver. But on trip up to my dads I did because it's a long drive and then filled and checked when I got there. I have no clue what my around town mpg is.

EDIT: And I bet my calculations are off because of tire size vs stock, so I probably got better than the 10 I did the math on.

 

[Horns]

Driving style has the biggest effect on fuel economy.

I honestly wish I could get 11MPG in my truck.

 

[Enginebuilder]

For S&G's, have a leak-down test and compression test done on the motor. When's the last time you changed the oil? How often are you running in 4x4?

Right now I'm lucky to get 9 MPG, but that's with poor compression on #1 & #6.

 

[19-Silverado-98]

4wd rarely gets used. Hunting season. It takes me about a quarter mile to get to 60mph. So I'm not heavy footed. I calculate it through a app on my phone. I change my oil every 2500 to 3200 miles. I'm very particular about my truck. It's my daily driver and I treat it very very well. It's just getting worse tho. It use to be around 13 about 2 years ago.

 

[Vortec Lover]

4wd rarely gets used. Hunting season. It takes me about a quarter mile to get to 60mph. So I'm not heavy footed. I calculate it through a app on my phone. I change my oil every 2500 to 3200 miles. I'm very particular about my truck. It's my daily driver and I treat it very very well. It's just getting worse tho. It use to be around 13 about 2 years ago.

spark plugs (and check the spacing when you put them in), cap and rotor, wires?

and to add to the driving part of it: do you downshift on hills? wait too long to slow down?

and are 265s the stock tire? if 245 was the stock tire, you have about 3.5% more mileage than the odo says

 

[BrightScrapMetallic]

I get 11mpg on my 93 v6 reg cab. There must be something really wrong with mine then.

 

[Vortec Lover]

I get 11mpg on my 93 v6 reg cab. There must be something really wrong with mine then.

yes and no- you should expect worse mileage out of the v6- especially if your working it

 

[gojo83]

I only have headers and dumped 2.5 in exhaust and a TB spacer and bigger intake tubing and a slight tune and I get 14+ on the interstate with 30+ mph side/head winds and all of this at 6100+ altitude just something to check against. Is there a way you may have a slight vac leak that could explain the drop aka dry rotted vac lines