Useless Information

[swathdiver]

One of the interesting things about my truck is that the previous owner never reset the fuel used counter and now it is about to surpass 8,000 gallons. The mileage just rolled past 120,000.

When purchased in May, the lifetime fuel economy average by doing the math was 15.4 mph and now it is 15.04; getting worse with me! Now I reckon those West Virginia hills helped the mileage as well as the cooler weather, I've never seen 18 mpg (an average lasting a tank full of gas) at any time since bringing it home from North Carolina.

Just completed a 1,200 mile trip and it's average fuel economy, fully loaded mind you, sits at 15.6 mpg.

In every other automobile owned, surpassing the mileage on the window sticker was easy, but not so with this truck! Maybe that's because the mileage on the window sticker was blank? LOL Published literature puts it between 14 and 15 city and 19 to 21 highway.

Do they get better mileage above 78 mph? I have a Montana that gets its best mileage at highway speeds that would make the driver well deserving of a ticket!

 

[adventurenali92]

Can’t answer your question about mileage. But I jsut thought about mine and it’s previous owner never reset the fuel used setting either. I’m gonna check it out in the morning and see what it says haha.

 

[randeez]

Trying to match mpg with e85?

 

[swathdiver]

Trying to match mpg with e85?

Have done that too but learned that the alcohol content of E85 varies widely so one tank of E85 gave 15.4 mpg and another under 11 mpg.

How many hours do your motors have on them? I'll have to check again to make sure but think mine is over 1300 hours. Saw another with nearly the same mileage that said 300 hours! Guess mine idled a lot!

My driving profile includes lots of idling, picking up the children from school, waiting while my wife runs into the grocer to pick up a few things, etc.

 

[moosehead]

The best mileage will be 60-65 mph.

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[moosehead]

Have done that too but learned that the alcohol content of E85 varies widely so one tank of E85 gave 15.4 mpg and another under 11 mpg.

How many hours do your motors have on them? I'll have to check again to make sure but think mine is over 1300 hours. Saw another with nearly the same mileage that said 300 hours! Guess mine idled a lot!

My driving profile includes lots of idling, picking up the children from school, waiting while my wife runs into the grocer to pick up a few things, etc.

Engine hours can be reset easily.

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[randeez]

Geez, I want to say mine has around 2700 hours lol... checked when I got back from lunch 2100.9 hours
Engine was replaced in like April though under powertrain warranty (ends this month)

 

[swathdiver]

Wonder what highway speed GM used to arrive at their highway mileage for these trucks?

 

[HiHoeSilver]

The best mileage will be 60-65 mph.

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Mine does best pinned right about 70. 3.42 rear.

 

[swathdiver]

3.42s here as well. So what do you get at 70? Just spent about 2 hours running errands and the average is just over 12 mpg. It's economy mimics a 2500 with the LY6!

 

[adventurenali92]

As of a little bit ago when I parked after working today, 103,450 on the odometer, 397.5 engine hours, and 9,053 gallons of fuel used! I think the engine hours may have been reset. I’m sure I’ve driven more time on the engine in the 2 and a half years I’ve owned my Denali than that. But over 9,000 gallons of fuel used blows my mind! Lol

 

[HiHoeSilver]

3.42s here as well. So what do you get at 70? Just spent about 2 hours running errands and the average is just over 12 mpg. It's economy mimics a 2500 with the LY6!

18ish.

 

[PG01]

3.42’s in my 13 tahoe and on a 2-2.5hr trip (4-4.5hr round trip) at 70-75 i got 17 with range device plugged in and 17.8 without it....

 

[HiHoeSilver]

My normal driving is about 50/50 local /highway. I usually average about 16 according to the computer. I run 89. It seems to give me the best results.

 

[swathdiver]

As of a little bit ago when I parked after working today, 103,450 on the odometer, 397.5 engine hours, and 9,053 gallons of fuel used! I think the engine hours may have been reset. I’m sure I’ve driven more time on the engine in the 2 and a half years I’ve owned my Denali than that. But over 9,000 gallons of fuel used blows my mind! Lol

That would make your truck's lifetime average fuel economy 11.4 mpg! I thought mine was thirsty! In truth it is better than my old '96 F-150 with the 302 which averaged 12 mpg and then just over 11 mpg after the flotation tires were put on to eliminate flats and ruined tires.

Now that the weather is getting cooler, the new plugs and wires will go in and maybe that will help the mileage. When Black Bear tuned the truck, he said it was running just fine both in feel and by watching the sensors. He figured the tune would be worth 1-2 mpg at least.

 

[adventurenali92]

That would make your truck's lifetime average fuel economy 11.4 mpg! I thought mine was thirsty! In truth it is better than my old '96 F-150 with the 302 which averaged 12 mpg and then just over 11 mpg after the flotation tires were put on to eliminate flats and ruined tires.

Now that the weather is getting cooler, the new plugs and wires will go in and maybe that will help the mileage. When Black Bear tuned the truck, he said it was running just fine both in feel and by watching the sensors. He figured the tune would be worth 1-2 mpg at least.

Yeah it’s lived for the couple years in the mountains so it’s alot of around town driving. It’s thirsty. lol. The DIC says current average is 14.6.

 

[iamdub]

Jenn daily drives mine and I'd estimate her driving mileage to be about 50/50 highway/city at best. Could probably be considered more city mileage than highway because I-10 is usually a parking lot. The MPG according to the DIC is usually around 16.2-16.4. Last road trip we took loaded with 2 adults, 2 kids, 3 suitcases and other misc. luggage, I averaged mid-20s cruising at 75. This was on I-10W through the Florida panhandle, AL, MS, LA...

 

[swathdiver]

I wonder how much your air intake and exhaust mods contribute? Seems like 2 or 3 mpg. Granted, mine weighs 5,900 pounds empty and is the regular length and 4WD but the six speed and 3.42 gear should make even the difference or get closer.

Another 2 hours in the truck today, same route, not as much idling, DIC went up to 13 then idled long enough to bring it back down to 12.7 mpg.

 

[iamdub]

I wonder how much your air intake and exhaust mods contribute? Seems like 2 or 3 mpg. Granted, mine weighs 5,900 pounds empty and is the regular length and 4WD but the six speed and 3.42 gear should make even the difference or get closer.

Another 2 hours in the truck today, same route, not as much idling, DIC went up to 13 then idled long enough to bring it back down to 12.7 mpg.

I just realized I didn't say what I meant in my last reply. When I said "mid-20s", I meant "20.5", not "25". Sorry about that!. Once I got off the interstate and cruising on the local highway at 65MPH, I got almost to 21MPG. Had that highway been longer, I would've seen that number on the DIC.

Anyway, I doubt my mods contributed much at all other than sound. I'm one to be pretty well in-tune with my rides and prefer to err on the conservative side when assessing results, but I MAY have felt a slightly stronger mid- to upper-RPM pull with the MIT and Dryflow filter. You and I both know there's no way deleting the resonator made any difference other than sound and appearance. I didn't drive it long enough with the stock intake to get any solid baselines. Maybe at this next oil change (in a couple of weeks) I'll put the stock intake tube back on for comparison. But there's no way that tube is good for any noticeable MPG improvement.

Do you reset your MPG gauge before each trip? If not, it's factoring in all the previous trips/idles/etc.

 

[swathdiver]

Ohh yeah, reset all the counters save for "fuel used". Just created an excel spreadsheet to log this until satisfied. I figured you meant 20 and a half, unless you didn't tell us about the gear vendors overdrive! LOL

Today my buddy gave me two bottles of Super Tech Concentrated Fuel Injector and Carburetor Cleaner, little 6 ounce bottles. He uses them in his Duramax when the mileage drops. We poured two bottles into my 1/2 empty tank and then topped the truck off down the street after breakfast. On the way home, the average was almost 19 mpg. Then began my usual daily round of errands which included about 20-30 minutes of idling and the DIC showed middle 14s when finished. Sure hope that does the trick.

He says those bottles are less than a buck at Walmart.