How do i fine tune the speed on my Gryphon?

[06KingRanch]

The speed on my Gryphon is reading 2-3 kph lower than my speedo (and gps).

I had done the tire calc and put in the proper diameter first. So then i moved the tire diameter up and down, thinking that this was how the Gryphon was calculating the speed, but it seemed to have no effect.

How do i get it to read the proper speed?
Note: I have the new beta metric download.

Thanks!

[bangingd]

I would make a drastic exaggerated change change to the tire setting and see if it has an effect on your truck speedo.

If it does then it's probably fine tuning the value.

If it does not change the truck speedo it is probably not writing value correctly.

Bill will be able to help you either way but it will save you both time to verify where the issue lies.

BTW the truck speedo will always be a little off (2-3 MPH) but the Gryphon and GPS should be right on.

[Jackpine]

Bangingd - Your avatar is outa sight!

However (and this is something I know from previous posts from Bill and have confirmed myself with a GPS and other ways), when the Gryphon's speed reading is dead accurate, the truck's speedometer will ALWAYS read about 2mph fast. Why? Because Ford designed it that way!

However, I've found that the difference is not constant. In the 75mph range, my truck's speedo is 2mph faster than actual, but in the 30-40mph range, it's about 1mph fast. And, through all this, my truck's odometer seems to be accurate.

You COULD reprogram the tire size to make the truck's speedo correct, but then its odometer won't be right.

My solution is just to use the truck's speedo and set the speed on the speed control 1-2mph over the speed limit if I want to drive at the limit.

So, 06KingRanch, I'd say you've set things up perfectly! (Sorry, I just HAD to be the first one to use her)!

- Jack

[Power Hungry]

Bikini Girl is one of the first avatars I swiped YEARS ago. She's cute and makes me smile.

As for the speedo, both posts were correct. The Speedo on the dash is always going to be slightly faster than the ACTUAL reading from the PCM. Ford designed it so that it always appears that your driving a little fast. In fact, most manufacturers do it. This does not have an adverse affect on the odometer, though. This always must be accurate.

As Jack said, if you set the speedo so that it is on spot with the GPS, the odometer will be inaccurate. Always best to line the GPS and the Gryphon (or Evo) up so they match and just live with the idea that the odometer is always off.

One other thing to keep in mind, in order to make a 1 KPH difference at 100 KPH, you need to make a roughly 1% difference in tire size. This means that if you are currently running 2530mm diameter for your setting, you'll need to make a 253mm change to get 1 KPH. Increasing diameter increases the calculated vehicle speed and reducing the diameter reduces the calculated speed.

Hope this helps.

[06KingRanch]

Originally Posted by Power Hungry

Bikini Girl is one of the first avatars I swiped YEARS ago. She's cute and makes me smile.

As for the speedo, both posts were correct. The Speedo on the dash is always going to be slightly faster than the ACTUAL reading from the PCM. Ford designed it so that it always appears that your driving a little fast. In fact, most manufacturers do it. This does not have an adverse affect on the odometer, though. This always must be accurate.

As Jack said, if you set the speedo so that it is on spot with the GPS, the odometer will be inaccurate. Always best to line the GPS and the Gryphon (or Evo) up so they match and just live with the idea that the odometer is always off.

One other thing to keep in mind, in order to make a 1 KPH difference at 100 KPH, you need to make a roughly 1% difference in tire size. This means that if you are currently running 2530mm diameter for your setting, you'll need to make a 253mm change to get 1 KPH. Increasing diameter increases the calculated vehicle speed and reducing the diameter reduces the calculated speed.

Hope this helps.

Thanks....that answers my question.....i had added to my tire size to see if the Gryphon's speed would go up , but didn't add enough to make a noticeable difference.

I had expected the trucks speedo to read high compared to the actaul gps speed.....but it appears to be dead on.

I wanted the gryphon to read correct so it's mileage calcs would be correct....or does it figure it off the trucks odometer?

If I raise the tire size so the Gryphons speedo is correct, will it effect any of the other Gryphon's outputs??

Many thanks.....i love the Gryphon....made a great deal of difference to my truck.....I'll give you a call when i get home in January to go over what mods make a difference, and order some custom tunes.

Scott

[Jackpine]

Originally Posted by 06KingRanch

Thanks....that answers my question.....i had added to my tire size to see if the Gryphon's speed would go up , but didn't add enough to make a noticeable difference.

I had expected the trucks speedo to read high compared to the actaul gps speed.....but it appears to be dead on.

I wanted the gryphon to read correct so it's mileage calcs would be correct....or does it figure it off the trucks odometer?

If I raise the tire size so the Gryphons speedo is correct, will it effect any of the other Gryphon's outputs??

Many thanks.....i love the Gryphon....made a great deal of difference to my truck.....I'll give you a call when i get home in January to go over what mods make a difference, and order some custom tunes.

Scott

Glad you like the Gryphon as much as the rest of us.

You DO want the Gryphon's speed reading to be exact - it gets all its input from the PCM, and nowhere else when it's working in the "monitor" mode. With the Gryphon showing speed correctly, the truck's odometer will also be correct (even though the truck's speedo will be about 2mph high). Remember, adjusting your tire size and gear information in the Gryphon reprograms the PCM so that it interprets tire revolutions for distance and speed correctly. As a side effect, having correct values programmed into the PCM makes the truck shift at the correct speed/throttle pressure points.

The gas mpg calculations will not be TOO accurate unfortunately. I suspect the PCM is not seeing an exact value for fuel flow into the engine. The average MPG might be within +/- 1 mpg though when you do a "hand" calculation dividing miles driven by gallons added to the tank at fillup. And, the instantaneous MPG will certainly tell you when you're "guzzling" gas or just "sipping" it.

- Jack

[Power Hungry]

In order to calculate MPG, we use the values from the Mass Air Meter and then calculate back from there to get mass fuel used. It's really a simple calculation, but can be affected by things such as Ethanol which not only has a slightly different mass per gallon, but also burns at a different stoichiometric ratio. This can cause a slight shift in the accuracy of the Avg. MPG readings versus hand calculated.

As for the speedo, yes... keep speed dead on with the GPS. All the other calculations (¼ Mile, 0 to 60, and Economy) require this to be as accurate as possible. This also helps keep the odometer accurate.

Enjoy all.

[glockwinger]

Originally Posted by JackandJanet

(Sorry, I just HAD to be the first one to use her)!

- Jack

................... :drool:...............

[Power Hungry]

I wanna be an avatar so I can hang out with her. :p