So, i tryed to adjust my tire size on my programer. And it said it didnt have the capabilites to change it and i needed to do a update? Shouldnt this be a standered capabilty?

 

What year is your truck and which model Gryphon do you have? Custom or canned tunes?

 

sorry, i was gonna put that in but i forgot. My truck is a 05 4.6l The model number is GPFG150_0484. I have no idea about the tunes. The programer was on the truck when i got it. Thanks for the help....

 

are you sure you're going through and using the proper steps to program a new tire size?

you can download a copy of the manual from PHP support page... www.gopowerhungry.com/_support.shtml

Another link>>>http://www.f150online.com/forums/chi...ions-menu.html

 

So it turns out that alls i had to do is unplug it and plug it back in. So found my circumfience of my tire by timesing 35 by 3.14 wich gave me 109ins. Then i converted it to mm's and i got 2792. But now gps has me going about 4 mphs slower then the speedo says. And when im driving around 40-45 mphs the tourge converter keeps locking and un locking. But that stops when i turn off o/d. Would this mean the tire size is too big? And if so, where did i go wrong?

Thanks agin.

 

This sounds like you simply didn't account for "squish" (the flattening of the tires due to the truck's weight) which effectively reduces the diameter of the tires. Try multiplying your 2792 by 0.97, which gives 2709mm and is a circumference that assumes a 3% squish. If that gets your speedo to about 2 mph faster than the GPS at 70 mph, you are "dead on" (the dash speedo always reads a bit fast due to mechanical errors but your odometer will be correct).

The larger tires may just be putting the engine under increased load at the 40-45 mph range, which causes the torque converter activity. It locks and unlocks based on speed and throttle position.

- Jack

 

Fine tune the tire size until the GPS agrees with the Gryphon speed, not the speedo.

 

I Change it to, 2707 which put the gryphon right on. The werid thing is i drove around for a couple days with the tires and not updating the gryphon, and i didnt notice the thing with the torque lock problem tell after i adjusted it the first time.

Another question, If the bigger tires ineffect change the gear ratio, does any adjust need to be made to the ration on the custom tunes? I looked and it says they are 3.55.

Thanks agin!

Todd

 

No, the gear ratio hasn't changed from stock, just the tire size. That's all the PCM has to know.