199 F-150 Gryphon Custom Parameters

[1999RedXLT]

I've been running the level two tune for a little over a half a tank, and I've noticed that the Gryphon seems to be under-reporting vehicle speed. The analog speedo in the truck agrees pretty closely with my GPS but the digital on the Gryphon seems to be about one mph or more low. What is the rounding algorithm? Does the unit round or just truncate the fractional mph?

I'm reluctant to open the custom parameters menu yet and start changing things, so my second question is, what tire size and gear ratio is the unit set up for? I think I provided my VIN to order, so did Bill look up the gear ratio and tire size (if it varies)?

As an aside, even if it is under-reporting speed and distance, my mileage seems to be up. I think the biggest cause is I can see the mileage and how my driving style affects it. So far, I have noticed one counter-intuitive effect. If I start off from a stop very gingerly and slowly accelerate up to the cruising speed (in town) I get WORSE mileage than if I hit it to about 1/3 - 1/2 throttle and get up to cruising speed more quickly. That may be because the towing tune is more efficient at lower speeds, or it may just be my imagination, but I thought it was interesting.

[Jackpine]

I love it when the answers are "simple"!

On your speed. You really want to adjust the tire size so you dash speedo reads about 2 mph (about 3%) fast at 70 mph. So, if your GPS reads 70, your dash should read 72 and the Gryphon should read 70. Why? Because that's the way Ford calibrates things to make your odometer accurate. Why?

So anyway, you should go ahead and bite the bullet and open the Custom Options Menu. You're going to have to "play" here. But, I'd activate Pegasus, enter your tire size in the "old" tire size window of the Gear Ratio Calculator, then change the "squish" to 7% (this seems to work for me) and read the Tire Size (TS) in the "Old Circumference" window. Try it. If it doesn't work, increase the size if your speed is being reported slow or decrease it if it's being reported fast.

Your error is actually pretty minor though. And if you didn't have a programmer, you and everyone else would not notice it.

The "reported" Average Economy" is probably not too accurate. I find mine is higher than a "hand calculated" value at fillup. But, you MAY really get better mileage by getting to a higher gear more quickly than "feather-footing" it from a standing start. Naturally, things are relative. I suspect if you "floored" it, you'd get worse mileage.

Your observations make sense to me - and good reporting of those observations!

- Jack