truck is getting 295/70/18 terra grapplers on it right now. id like to change it in the tuner when i go pick the truck up. im guessing to do this you turn the key to on, then go to power programming, then select the tune i want (2-87 octane tow, canned) and then when it asks if i want to make a custom program i select yes ? correct?

then once i get in there what do i need to know revs per mile or the actual tire size? or the diameter?

i know not to change much in there since i can mess things up, so i will understand how to scroll through the selections to find tire size?

then also, separate ordeal, i really dislike with my truck how if im traveling at say 45 mph, and a car in front of me slows to 25 mph or so to turn off, and then when its clear and i give the truck throttle, its like the truck is still in overdrive, because when you give it throttle it will take a second to downshift, then it will downshift again sometimes before finally moving the truck forward. is there a way to change the point at which the truck changes down to the next lowest gear? for instance will there be an rpm of when the truck shifts from od to 3rd gear? and can i raise that up so it will do it sooner? or is this something i need to have bill write me a custom tune to change? sometimes it searching for gears after slowing down is so violent that i get a good clang when it hits the gear.

thanks in advance

 

Yep you about got it......check and make sure the gear size is correct also....

The tire size will use the circumference in mm's.......start off by using 2597......that's 2734-(5% for squish)136........

 

So if its a 34.1 inch tire I convert that to mm then subtract 5% of that number for the squish and that's what I enter in?

 

Sorry I meant circumference .....start with the value 2597 and confirm with gps, mile markers, or odometer of a known distance...

 

oh so youve looked up my tire size and the one that will get me closest is 2597. meaning when i go in there the value that should be loaded in there right now will be much less than 2597. correct? i have a garmin that i can setup to watch, so i need to try 2597 first?


also, any advice on the downshifting thing?

 

I used your tire size and put it into the php formula and minus the squish of 5%.....the php tire formula is in the gryphon manual.....remember when you open custom options to change the the tire size you have to check the the gear size also.......

As far as the down shifting issue you should probably talk to Bill .....

 

That's what I figured. I appreciate your help ill try that number

 

Your shifting, fivespeed, is probably the shift strategy in the truck. From your description, coasting behind a slowing vehicle, it would probably stay in 4th gear with the torque converter unlocked. Then as you start to speed up, the TC may lock at least briefly, but the opening throttle and speed will command a 4-3 downshift. You open the throttle a bit more and a 3-2 downshift is commanded.

I've felt this several times driving in the LA area, where the traffic doesn't know how to maintain a constant speed. Not so much here. There's really not a lot you can do about this I think, except change the part throttle upshift/downshift and TC unlock/lock points some. You can do this in the custom options menu when you load a tune. If you reduce these points (I've done it to the max), the truck will upshift quicker on acceleration and the TC will lock sooner, and, it will downshift and unlock the TC at a lower speed.

I did this mostly to try to keep the truck from downshifting when climbing a hill on the highway. It seemed on gentle inclines, it was too eager to shift into 3rd gear.

- Jack

 

so adjusting those values down wont change what im talking about just try to chug a higher gear for longer?

 

That's what I think, fivespeed. I'm hardly an expert though. I just know the part throttle shift strategy built in to our trucks depends on vehicle speed and throttle opening. A very gradual acceleration will result in upshift to 4th gear at the lowest speed. If you step on it (short of going into Wide Open Throttle - about 90% open), the truck stays in lower gears longer.

The reverse is true as the speed drops. If you were to try accelerating very gradually, once you pass the "grandpa", it would probably not downshift into 2nd.

So, high speed, small opening commands an upshift or keeps it there. Big opening, and low speed, directs the gears to a low range.

A tuner, like Bill Cohron at PHP, could tell you if this can be changed. I suspect there's not a lot you can do about it.

- Jack

 

I set that rev per mile but the speedo is 1 MPH slower than it should be. So put the member up or down by how much?

 

Which speedo?
The gryphon speedo or the dash speedo?

And at what speed?

 

Read>>> https://www.f150online.com/forums/ch...djustment.html

I knew I had seen that tire size before....

 

the trucks speedo is 1 mph slower than gps, according to the trucks gryphon. they used to sync up. hard to read the dash speedo, ill have to get it right at 50 or so and see what the gyrphon speedo says. this was done at 53mph gps (garmin nuvi) and the gryphon speedo said 52, dash looked to be right at 52.

yup same tire size. i figured that the squish was too much since the tires are new. makes sense they are all firm and not squishy yet. i will try a 3% squish rate tomorrow and try to hit a highway and test at 65.


edit: just went out and put the 3% squish value in, which ended in a 52, when i put the value in and hit enter, then went back in, it rounds itself to 60. that normal?

 

Fine tune it till the GPS agrees with the Gryphon speedo, not the dash speedo. The dash speedo will probably be 1 or 2 mph high.