brock mann

My buddy drives like grandpa. Sets the ruise at 60-65 and just drives. I've seen it with my own eyes. I want to know how the hell he does it when I can only get 12-13 out of my truck in city or highway.
I starting to get the idea that these number are pretty normal for these trucks.
I guess I'll learn to live with it or sell it and 5.3 another s10 Zr2.

kr1s

What MPG do you want out of your truck?

dmelvin

iTrader: (8)

Yeah... something definitely seems off. I'm getting 18MPG HWY @ 70-72mph with crappy winter gas. If I'm nice to it in the summer I can pull 20.

brock mann

I'm just looking to get better than 12-13. I like my truck but with gas going upto 5.00 a gal this summer. My sonoma zr2 gets 16 in town and 18-20 on the innerstate.

nonnieselman

iTrader: (10)

When i had a turbo on my 2000 EC 2wd with 3.42s and 275/60/16s 6.0 and 80E
i went to the south east texas track day and averaged 24mpg on 1100+ miles round trip
I had tuned it to lean out cruising and ran 93 Oct and babied it on the interstate at 70mph..

Now its back N/A with just a Isky 215 cam and im averaging 14.5-15 on my daily commute which is only 28 miles but the last 6 miles to work in the morning is idling on the freakin interstate goin 0-15mph and stopping.. it sucks badddd.


you never mentioned tire size or gear ratios... have you checked to see if your speedo is calibrated?

5.3 GMC

My 99 rc 2wd would get 22 on the interstate. 3.42s and just cruising at 70. Headers, Cai, efans, and a handheld got it there. I've seen 23.2 out of it. And that's no bull. I've got witnesses. But then I threw it all away, went 4.11s, truetrac, cam, procharger...yeah...it gets about 15 now on a good day. And a good day is when I'm deathly ill and just putin around...haha!

brock mann

Right now I'm running BFG 285/75R16 on factory rims. When the weather clears I'll put on the 277/55R20. I think I have 3.73. My Daily drive is around 3 miles on way.
I know this kills the milage because the truck never warms up, but even when I fill it up before and after along trip I still on get 12-13 mpg.
I am thinking of either getting the computer tuned or getting a bullydog programmer. A coworker has on for his Yukon and his milage when up from 12 to 14+ around town and close to 20 on the inerstate.
How and where do I get my speedo calibrated?
Where would I find a break down of the axle codes to verify my gear ratio. On an s10 I'm golden, but this is my first Silverado.

rel3rd

iTrader: (42)

Well, right off the bat, a 285/75/16 tire is 2 inches taller so any MPG calculations with stock speedo calibration is incorrect. Not to mention, it's probably kinda doggy with nothing else done to it, really. And...BFG's are some heavy *** tires, especially if you have the Load Range E's.

The 275/55/20's should be the same height as your stock size 265/75/16 tires, but they'll surely be heavier, and MPG naturally suffers with heavier rolling resistance no matter how great the tuning is or isn't.

I calibrate my speedo by using a nice flat road, setting the cruise at 55 mph and comparing it to my GPS. I have yet to find any chart or graph that's 100% correct as far as simply changing to some generic numbers in the tune and it being "right".

With the speedometer not being calibrated, you're also driving a truck that doesn't have any of the shift parameters, torque converter lockup speeds, etc. not being anywhere near optimum.

I'd get it tuned now, and simply re-tuned when mods are complete. The stock tune on my own truck was nowhere even close to being optimum, and I can't imagine yours being so either...especially with taller tires than stock.

I've had 285's on my truck and 275/55/20's and both made the truck noticeably slower and less responsive. Common sense says that if the trucks takes more gas to get it going, which taller and/or heavier wheels absolutely will do, then mileage will suffer, period.

Good Luck.

Cknox121

iTrader: (1)

I have a 01 4x4 z71 5.3 ecsb, full bolt on's and a BBP tune to 93, 33 1250 18 mud grapplers on rockstars. I average about 15.5-16 in interstate and about 12.5-13 in town.

The tune supposedly recallibrated the speedo but my gps and speedo read 2 different speeds when driving.

I have a few buddy's with the same truck at they all get around 12-16 in town. It's probably more how you drive then anything.

I actually get better if I make the truck shift about 2500rpm instead of babying it and shifting under 2k.

rel3rd

iTrader: (42)

If they don't match, then it isn't calibrated. That's what I meant above that most just put in a generic number in the tune from some chart or whatever, but if it isn't gps verified, then how can it really be calibrated correctly to YOUR vehicle?
Maybe if your speedo was accurate, it might shift a little closer to your 2500 without manually shifting?