Gryphon avg mpg vs lariat message center's

[bossman15]

I'm trying to figure out my mpg difference with my gryphon and then when i get my custom tunes but i dont know what mpg to go by. The gryphon has it at 15.2 right now but my lariat message center has it at 13.2. I just dont know which to believe. I've heard the stock one can be off at times and the fact that the gryphon is plugged directly in the obd port leads me to believe its a little more accurate but i dont know. any body know which is more accurate straight off so i dont have to compute it the old fashion way? :cheesy smile:

[Jackpine]

I'm trying to figure out my mpg difference with my gryphon and then when i get my custom tunes but i dont know what mpg to go by. The gryphon has it at 15.2 right now but my lariat message center has it at 13.2. I just dont know which to believe. I've heard the stock one can be off at times and the fact that the gryphon is plugged directly in the obd port leads me to believe its a little more accurate but i dont know. any body know which is more accurate straight off so i dont have to compute it the old fashion way? :cheesy smile:

Bossman, I'm going to move your thread into the Gryphon section, because it doesn't really seem you have a problem that Bill or Corey needs to deal with.

I have a message center in my truck too, and I've always found the Gryphon seems to be higher, and less accurate than my message center's readout. I think the message center uses a smaller number of samples than the Gryphon. Bill says the Gryphon uses 100,000 readings for its average, and I seem to recall they are about 1 second apart. This works out to an average over about four tankfuls of gas, and I know the message center changes more rapidly/frequently than the Gryphon, so I'm certain the sample size is smaller.

It doesn't really explain why they should be different, or why the Gryphon should read high for you and me, but I DO think the effect of the smaller sample size is to make the message center average mpg closer to what you are currently getting, as opposed to over a month's period (if you fill up once a week).

Regardless, once you determine the normal error, it seems to be pretty consistent. You could just use the Gryphon's reading and subtract the error.

- Jack

[shotgun]

Don't know if this helps, but over the first 6500 miles (since June 13) my message center has averaged .8 (per tank) higher than the actual calculated value.

[bossman15]

Haha that makes me more sad lol. So how would I go ablut finding this "error" to subtract from the gryphons?

[88Racing]

I just tune out those displays and use a pencil and calculator along with a log book.

[shotgun]

I just tune out those displays and use a pencil and calculator along with a log book.

This is the one that I use: http://www.vertex42.com/Links/go.php?urlid=file-mileagecalc

I modified it slightly (added columns for the truck computer value, error/difference, brand and location, and comments):

[88Racing]

This is the one that I use: http://www.vertex42.com/Links/go.php?urlid=file-mileagecalc

I modified it slightly (added columns for the truck computer value, error/difference, brand and location, and comments):

That looks like a great tool to use!

There is also a couple of web sites that will host your info also. Kind of like a bulletin board. The only things about them is they make your figures public and you have to enter the figures they want.

[Jackpine]

Haha that makes me more sad lol. So how would I go ablut finding this "error" to subtract from the gryphons?

I was thinking of something simple, like the Gryphon says 15.5, but you calculate 14.7. You need to subtract 0.8 from the Gryphon to get your real mileage. Just keep track of the difference over a few tankfuls and I suspect you'll find it's fairly constant.

- Jack

[88Racing]

In the long run the message center is more consistant than the gryphon.
The message center varies .1-.3
The gryphon varies .5-1.5

[PZX_2002]

Here is a test that I have done time and time again so this is accurate on my truck.
These are the readings I logged with the canned Gryph 87 tow tune:
message center = 12.0 mpg's
Gryphon = 14.5mpg's

So when it states 12.0mpg's it is really 10.7 using "good-o'l-fashion" tools, pen n paper. The message center on my pickup is off by -1.3 mpg's and as for the gryphon, I could not count that high. :)



2007 F150 SCrew
stock 4x4

[06FX41992]

Here is a test that I have done time and time again so this is accurate on my truck.
These are the readings I logged with the canned Gryph 87 tow tune:
message center = 12.0 mpg's
Gryphon = 14.5mpg's

So when it states 12.0mpg's it is really 10.7 using "good-o'l-fashion" tools, pen n paper. The message center on my pickup is off by -1.3 mpg's and as for the gryphon, I could not count that high. :)



2007 F150 SCrew
stock 4x4

Thats how it is for me too, only I don't have the message center readout. My Gryphon is reading 12.5-13.5 and when I do it by hand I get around 9.5-10.5. Its kinda frustrating, but most of the frustration is from the gas mileage itself. I guess 35 inch tires and a steel replacement bumper might have something to do it... Oh, ya, and a heavy right foot... :D

[Power Hungry]

One of the problems is that when the calculations for economy were written, it was for straight gasoline. Now with 10% ethanol blends being more prevalent, this changes things considerably as far as MPG predictions go but the algorithms have never been updated. The readings used to be considerably more accurate a few years back. I guess I'll have to revisit them and make some adjustments.

[Jackpine]

One of the problems is that when the calculations for economy were written, it was for straight gasoline. Now with 10% ethanol blends being more prevalent, this changes things considerably as far as MPG predictions go but the algorithms have never been updated. The readings used to be considerably more accurate a few years back. I guess I'll have to revisit them and make some adjustments.

Now THAT makes sense to me! Thanks, Bill.

- Jack