Beat my best MPG and ran B20 in the 3.0 Duramax Refresh (dash reads incorrect)

DemonWorks · September 26, 2022

I hand calculated my miles on a recent 13xx mile road trip - surprised how far off the gauge cluster is.

Also ran B20, it worked but I prefer to not run it if I don't have to

I have a trip in two weeks where I am towing and I will document the mileage on that as well (exact same trip) then after that, I should be in the LZ0 and we have sema coming up !

redwngr · September 27, 2022

I didn't watch the video.

What are the hand calc and dic 'trip meter' numbers?

jdrockin · September 27, 2022

I put on a lot of highway miles. Last tank was towing

Dirk13 · September 28, 2022

Lots of variables can affect hand calculation vs DIC mpg. The biggest of those variables is How far the tank gets filled because it’s not always exactly the same. 1300 miles isn’t much of a sample size and I wouldn’t claim the dash is “incorrect” based on that.

I track every single fill up, resetting the trip at each fill and also hand calculating.

In my 2021 hand calculation was anywhere from 0 to 1.25 mpg higher than the DIC, averaging out at .65 mpg difference. This was over 32000 miles and 84 fill ups.

in my 2022 refresh, so far in 19 full ups over 7500 miles, the overall average of all hand calculations is .34 mpg lower than the overall average of all DIC trip mpgs.

I wouldn’t say that in either of my trucks the dash was “incorrect”. Something seems to have changed though (should be obvious since the truck has entirely different electrical architecture) since my hand calcs were consistently above the DIC and now they are below. Even still I consider the new truck more accurate because the averages have less of a delta.

Grumpy Bear · September 28, 2022

14 hours ago, Dirk13 said:

Lots of variables can affect hand calculation vs DIC mpg. The biggest of those variables is How far the tank gets filled because it’s not always exactly the same. 1300 miles isn’t much of a sample size and I wouldn’t claim the dash is “incorrect” based on that.

Incorrect is not the same thing as imprecise and I agree that the sample set it to small to know much of anything but the result. I agree as well with the reasons.

14 hours ago, Dirk13 said:

I wouldn’t say that in either of my trucks the dash was “incorrect”.

However the sample size, especially of the first case, is large enough to reveal the 'central tendency' with a very high degree of 'probability'. If they don't match it is indeed "Incorrect". They match or they don't. Kind of the definition of correct, right? It's "precision" is dictated by the 'standard deviation'. If that falls within 1 sigma it would be of little concern.

I keep both numbers in my spreadsheets and the delta and calculate the standard deviation of the difference. It's never ever zero. Some vehicles it's very close and some are not even in the same zip code.

redwngr · September 29, 2022

25,000 miles of 'trip meter vs hand calc:

Most, but not all, are from the same commercial pump.

4banger · September 30, 2022

my 2022 2.7 computer has proven so accurate in first 5000 miles I won't need to hand calculate going forward, it's been either dead on or within 1/10th of actual and most of the time it reads 1/10th out it's read conservatively, ie; it's 1/10th higher than hand calc'd...best accuracy I've seen from a vehicle yet but you gotta be tallying about 3/4's of a tank usage each time imo

jdrockin · October 1, 2022

15 hours ago, 4banger said:

my 2022 2.7 computer has proven so accurate in first 5000 miles I won't need to hand calculate going forward, it's been either dead on or within 1/10th of actual and most of the time it reads 1/10th out it's read conservatively, ie; it's 1/10th higher than hand calc'd...best accuracy I've seen from a vehicle yet but you gotta be tallying about 3/4's of a tank usage each time imo

My ‘21 LM2 computer performs similar to yours, it is never off by more than a tenth or two (typically even reading lower mpg vs hand if it is off). I’m shocked (and very pleasantly surprised) at just how accurate it is. I still log every single fuel up/service etc but it is nice to confirm that what I’m seeing on my dash reflects how the truck really is performing.

DemonWorks · October 6, 2022

My first and last fill ups were filled the same - Fill then let sit for 30 seconds and fill it again until it shuts off. I'm happy with that feeling of doing it correctly.

Trip 1 (to CA) 676.1 Miles / 26.48 Gallons used / 26.9 MPG on cluster / 25.53 Hand Calculated

Trip 2 (to Utah) 667.3 miles / 27.15 gallons used / 27 MPG on cluster / 24.58 Hand Calculated

1343.4 miles total / 53.63 Gallons used / 25.04 MPG Hand Calculated

Just under 1 Gallon DEF Fluid used

Towing this weekend and I added the S&B intake back on the truck. Will see what numbers I show with that.