Improving the MPG on A Suburban

[SaabLover]

I am sure that this has been asked many times although when I search I found everything but.

I'm sure most of you know that I just bought my new to me 1999 suburban 2500 with a 7.4 L engine. Well I must say it's been a real awakening I knew the gas mileage would be bad but I wasn't ready for the 11 miles per gallon. And that is without my airstream in-tow. What will I get then 8 miles a gallon? Now I know for the most part this vehicle is in decent shape: tires are new, shocks are fairly new, brakes are new, oils just been changed, also the air cleaner is brand-new. So I put it to you experts out there I just want to make sure I have done everything I can possibly do to squeeze even a mile or two per gallon more would be nice. I was thinking of changing the plug wires, plugs and oxygen sensors. I think there are two right? I can't tell about the fuel filter would that help? Any other ideas would be welcome. Now I know most of you guys out there know a lot more about this than I do so if he wouldn't mind lending me your expertise to this never-ending search for better MPG.

[Boondocker]

Tune ups, air pressure, driving habits. Slow starts and stops, keep it under 60.

[uwe]

Originally Posted by SaabLover

I am sure that this has been asked many times although when I search I found everything but.

I'm sure most of you know that I just bought my new to me 1999 suburban 2500 with a 7.4 L engine. Well I must say it's been a real awakening I knew the gas mileage would be bad but I wasn't ready for the 11 miles per gallon. And that is without my airstream in-tow. What will I get then 8 miles a gallon? Now I know for the most part this vehicle is in decent shape: tires are new, shocks are fairly new, brakes are new, oils just been changed, also the air cleaner is brand-new. So I put it to you experts out there I just want to make sure I have done everything I can possibly do to squeeze even a mile or two per gallon more would be nice. I was thinking of changing the plug wires, plugs and oxygen sensors. I think there are two right? I can't tell about the fuel filter would that help? Any other ideas would be welcome. Now I know most of you guys out there know a lot more about this than I do so if he wouldn't mind lending me your expertise to this never-ending search for better MPG.

Driving habits is where it's at. No snake oil will make this beast into an economy car. Take it easy on the gas pedal. Drive lazy, but not annoyingly so. Calculate stops - hard braking wastes gas that was needed to get you to speed in the first place. I was able to get my 97 to about 16mpg in town, and close to 20 on the highway. 12 towing.
I would just ease away from the lights, and build speed slowly, but again, not to hinder the flow of traffic.
Your actual highway mileage will be much better if you keep it below 70. Expect about 16mpg on long trips solo with the 454.
If the vehicle is well maintained, then that's really all you can do. There's a reason they gave it a 42 gal tank....

[ROBERTSUNRUS]

Hi, in most cases you can't do much of anything to improve mileage beyond driveing slower and makeing things lighter. Changeing the parts you mentioned will only make it better if they are bad and the check engine light is on because of it. We need to know more about the truck; Is it jacked up [raised] or does it have larger tires and wheels? This will effect the mileage. And if larger tires and wheels were put on it without recalibrateing the speedometer, you will get a false speed and mileage. The speed will be faster than the reading on the speedometer and the mileage will be less than actual.

[doorgunner]

11 is pretty good! Mine gets that empty or pullin the Excella on flat land.I seldom go over 65 , seems to settle in around 62. Going up to Tahoe you can almost watch the fuel gauge move. 8 mpg uphill.
get the pics?
Also the 454 does eat more fuel going 35-40 mph.

[Kevbo10]

Originally Posted by SaabLover

I am sure that this has been asked many times although when I search I found everything but.

I'm sure most of you know that I just bought my new to me 1999 suburban 2500 with a 7.4 L engine. Well I must say it's been a real awakening I knew the gas mileage would be bad but I wasn't ready for the 11 miles per gallon. And that is without my airstream in-tow. What will I get then 8 miles a gallon? Now I know for the most part this vehicle is in decent shape: tires are new, shocks are fairly new, brakes are new, oils just been changed, also the air cleaner is brand-new. So I put it to you experts out there I just want to make sure I have done everything I can possibly do to squeeze even a mile or two per gallon more would be nice. I was thinking of changing the plug wires, plugs and oxygen sensors. I think there are two right? I can't tell about the fuel filter would that help? Any other ideas would be welcome. Now I know most of you guys out there know a lot more about this than I do so if he wouldn't mind lending me your expertise to this never-ending search for better MPG.

buy a dodge w/ a hemi...

it's soooo easy.

i get 13.5 doing 85 str8 up hill... fully loaded... on regular gas. could do 95, but hay even i have limits...

kevbo

[SaabLover]

Originally Posted by ROBERTSUNRUS

Hi, in most cases you can't do much of anything to improve mileage beyond driveing slower and makeing things lighter. Changeing the parts you mentioned will only make it better if they are bad and the check engine light is on because of it. We need to know more about the truck; Is it jacked up [raised] or does it have larger tires and wheels? This will effect the mileage. And if larger tires and wheels were put on it without recalibrateing the speedometer, you will get a false speed and mileage. The speed will be faster than the reading on the speedometer and the mileage will be less than actual.

I know I know I do need slow down a bit. Changing over from my town and country and the Saab. It is a bit of struggle keep my foot out of the gas tank. The tires that I am running are what came on it. Their new Firestone 275 X 75 X 16. I do think it is jacked up a little bit. It seems to be higher than most I believe. When I saw the tires I was wishing I were 245s. I'm still getting used to having to use the step to get into the damn thing. What foot to start with and all that. In my Saab I have to climb down into IT.

[lsinclair]

Aside from what already has been mentioned, avoid jack rabbit starts/stops and check tire pressure -cold. I noticed your running 265/75R16's, when needing replacement might suggest 235/85R16 (little higher and narrow). But the aspect ratio is nealy identical thus no speedo error. As far as tune ups (a generic phrase in todays product), your check engine/service engine light will come on when the air/fuel parameters are exceeded on either end (rich or lean). Hence your computer via the light will alert you to most driveability issues (i.e. misfires). Your gear ratios 411's, 373's also have a small impact on yor MPG's. Before spending $, consider the trade-offs.
Good luck, Larry

[richinny]

how were the readings from the state inspection? if they were well withing range i don't think changing what you mentioned will help any.