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no fuel mileage with second suburban with 6.5 or cimmins.

H

hereismylife

formerly j k auto
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Location
pa
I came to the conclusion there is no fuel mileage with the 6.5 or cummins. All three engines get 10 around town n 20 on highway.

I have no ideas how you can average anywhere over 12 around town or 21 on the highway.

Did many things over the years and read and talked about this to many people.

I wish these would just be around 20 all the time.

Now with this new truck. All stock hoping my nog were going to be around 20. Well same problem with my other burban....no mpg.....


:mad2:
 
On the Cummins you need to keep the boost and egt down for best fuel economy. Stay below 2000 rpm, 1800 - 2000 rpm is the sweet spot. You are running a lot of injector and a lot of fuel. How much power do you need? Might consider cutting down the fuel some. Got an intercooler? Does it leak? You also want the 195 degree thermostat, they like to be hot. Electric fans can be worth 2-3 mpg on the Cummins. I ran a set of Flex a lites on a Dodge 2500 and it was money well spent. How much tire are you running? Big aggressive tires kill mpg. You might want to do some reading over on TDR, those guys are the best for knowledge on the 5.9.
 
That don't sound that good for the CUMMINS, they did better than that in the full sized DODGE trucks. I know I can get an honest 17-19 around town if I baby it with the DURAMAX, and get a consistent 21 running 70-72 on the interstate with a heavy foot. I've seen as high as 23 running 60-65 with about 30% stop and go driving mixed in. That CUMMINS should be able to mop the floor with my milage numbers though.
 
I know what all of you are saying. We tried many different things. Going from stock to where I am at now with 2 6.5 and my cummins. All 3 run about the same. Many $$$$ & time later mpg never got better so to speak. Now I got this stock 6.5 on different truck...thought it was my truck because everyone said it was the truck. Now new truck n same mpg all stock. So now I find out both trucks get same mpg....I would love to know what the window sticker says for mpg since I have a stock truck...probably say 10 city n 18 highway.
 
Whats your cruise speed at 2000 rpm on the cummins truck? What is the EGT and boost at that rpm steady speed? What tire are you running
 
After i bought my truck i looked up the fuel economy, when my truck as sold from the dealer it was estimated at 17 city 20 highway and it seems to be close to that.

Maybe if you changed out your fluids with synthetic you could help out your mgps
 
Jorge6.5 said:
After i bought my truck i looked up the fuel economy, when my truck as sold from the dealer it was estimated at 17 city 20 highway and it seems to be close to that.

Maybe if you changed out your fluids with synthetic you could help out your mgps
Click to expand...

Everything I own I run Amsoil....
 
Guster said:
Whats your cruise speed at 2000 rpm on the cummins truck? What is the EGT and boost at that rpm steady speed? What tire are you running
Click to expand...

Right now my 5.9 has no trans...It is hard to find a 48re core that I can rebuild the way I need.
 
Is your city driving a lot of stop and go? Heavy foot? Seems quite low for a Cummins.
 
My friend has a lifted P-Pumped 24V w/ NV4500 and 3.55 gears running 33's and gets 24 highway and 20 in town. He babies the truck everywhere but the dyno lol. ~550HP iirc
 
have you changed the timing on your cummins for the best mileage? i notice you dont run a fuel plate. Have you thought about tuning the afc for less fuel down low? Are you sure your speedometer is right?
 
Don't take this the wrong way, but your numbers are off somewhere. Either your odometer/speedometer is off or your gear ratio is out of whack. Something. I get 20 MPG in the truck in my signature on highway. I average 18 MPG city driving. That's been consistent since I put the Optimizer in. I agree with Thefermanator, the Cummins should be doing 5-6 MPG better than my truck is getting.
 
I think something's off there, as well (driving style?) with the 6.5. I don't get as good of MPG as some of the pickup truck guys, but even in winter I get a solid 14MPG around town. I rarely get a chance to do any type of distance on the highway unloaded, but last year I did a small trip (about 250 miles roundtrip) that had about 70% on the highway at 65MPH (the rest city and dirt/gravel road going to the cabin) and I got a bit over 19MPG.
 
When it comes to the cummins I gave up with mpg. I just drive it. I was hoping this stock 6.5 1500 would of got higher numbers. But up to date I am getting 9 to 10 mpg. So yea I am glad everyone gets good mpg but not me....I just don't get it...I guess if I drive only on the highway at 55 maybe I will see 15 mpg... Also I replaced the Injectors hoping my fuel mpg would be up to date...I guess that was a waste...
 
Hey - just saw "formely JK Auto"... Hi Joe!

I don't know - something's up. Theoretically, you should be getting even better mileage than me since you have a 21:1 (is the 1500 lighter than the 2500, too?).

I get that 14mpg consistently (and I fill up about 35-40 gallons at a time so it's a good measure). Just checked my mileage charts and it's been creeping up to a bit over 15 lately. It might be due to the new additive I am using... not sure, yet.
 
I kinda give up honestly with the mpg idea. all 3 engines and both trucks give me about the same mpg... I do hear ya with something is up but I think I drive to short of distance and it brings it way down. I do know my cummins does a little better but not like most guys. Maybe the scanner could tell me more once I get a laptop then I can run it.
 
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