Odometer/Speedometer calibration

[TonyJ]

So far after playing with the PSI a little I got them where I want them. I ended up running 60 PSI/65 PSI cold. They end up heating up to like 65/70 PSI. As any AT they are louder as such not too bad at all.

Thanks a bunch!

 

[Dahlsfarrier]

Forscan won’t go to 37s. At least I couldn’t get it to. It tosses up a CEL

It will, I was running 37s for awhile and had it calibrated with forscan dead on to gps speed. I’ll see if I can find my notes on the number I used.

 

[Chris-DTA]

It will, I was running 37s for awhile and had it calibrated with forscan dead on to gps speed. I’ll see if I can find my notes on the number I used.

Wanted to check and see if you were able to find your notes about this.

 

[Boarder1995]

I just messed with ForScan yesterday and the only number larger that stock Tremor (2689) I could get to work was 2770. This is currently working for me without CEL light or any other warnings. 2022 6.7

 

[MCRTREMOR]

You can do it with forscan but it throws the CEL. I tried it on mine and I figured I could live with the speedometer not being accurate rather than a CEL.

 

[Dahlsfarrier]

Wanted to check and see if you were able to find your notes about this.

Sorry, I’ve been working a bunch and haven’t been around. The number I used in forscan is 2770 for 37’s. You have to do a PCM AND TCM relearn after. That will shut off the CEL.

 

[thatdood]

If you don’t update/adjust the speedometer to account for the larger tires, won’t the odometer read lower than the actual miles traveled? This would also impact the computers estimated mpg to empty showing a reduced number?

 

[HeavyAssault]

If you don’t update/adjust the speedometer to account for the larger tires, won’t the odometer read lower than the actual miles traveled? This would also impact the computers estimated mpg to empty showing a reduced number?

Using the Engineering Mode you can adjust the AVG MPG calculation to get closer to a hand calculated number. I'd suspect that would change the Till Empty numbers.

 

[TomSkerritt]

If you don’t update/adjust the speedometer to account for the larger tires, won’t the odometer read lower than the actual miles traveled? This would also impact the computers estimated mpg to empty showing a reduced number?

Correct

 

[thatdood]

Using the Engineering Mode you can adjust the AVG MPG calculation to get closer to a hand calculated number. I'd suspect that would change the Till Empty numbers.

Not sure what happened, but today without any adjustments I went from 280 M to empty to 490… Much closer to what stock was showing

 

[HeavyAssault]

Not sure what happened, but today without any adjustments I went from 280 M to empty to 490… Much closer to what stock was showing

I can say that I've noticed any significant change in driving can/will make the DTE change.

 

[Modman]

I can say that I've noticed any significant change in driving can/will make the DTE change.

DTE is a moving average and updates periodically based on most recent driving. I can't say that I know what the frequency is but suspect ~30min.

 

[thatdood]

DTE is a moving average and updates periodically based on most recent driving. I can't say that I know what the frequency is but suspect ~30min.

Yeah I get that it’s dynamic, but it was really odd that after I added the 37’s and Carli 5.5 kit, I went from like 480M on full tank to 250 or something. I guess I finally drove enough after the tires and lift to let it recalibrate

 

[HeavyAssault]

Yeah I get that it’s dynamic, but it was really odd that after I added the 37’s and Carli 5.5 kit, I went from like 480M on full tank to 250 or something. I guess I finally drove enough after the tires and lift to let it recalibrate

If you want those numbers closer to actual you need to get some good data from your fuel fill. Then use those numbers to change the setting in Engineering mode. I dropped my number to 980 seeing a "better" AVG MPG closer to my hand calculated numbers. I'm within 1 MPG between AVG MPG and my hand calculated (Fuely App) numbers. Yesterday while HWY driving I noticed that for every .1 AVG MPG gain my DTE number increased about 2-3 miles. Yes, this will not be as dynamic as time goes on, I just happened to have fueled up the other day. The more you burn down your fuel tank the "better" your actual fuel numbers can be tracked. I hate seeing people report MPGs after 100 miles...it's just not good data. Drive 500+ miles between fill-ups...your numbers become more realistic.

 

[HeavyAssault]

DTE is a moving average and updates periodically based on most recent driving. I can't say that I know what the frequency is but suspect ~30min.

In the menu pages the graph is 6 bars, 5 minutes each, showing a "30 minute" history. It's possible it's changing on the 5 minute mark. My HWY driving yesterday was pretty dynamic for the changes in AVG MPG and DTE numbers.

 

[Modman]

In the menu pages the graph is 6 bars, 5 minutes each, showing a "30 minute" history. It's possible it's changing on the 5 minute mark. My HWY driving yesterday was pretty dynamic for the changes in AVG MPG and DTE numbers.

That graph is what I am basing my experience on... For me the DTE doesn't seem to change as often as each bar, but possibly correlated with the cycle of six.

 

[HeavyAssault]

That graph is what I am basing my experience on... For me the DTE doesn't seem to change as often as each bar, but possibly correlated with the cycle of six.

I agree. With the increased overall time since any resetting the overall AVG MPG change slows down. Since I had just reset the Trip #1 my numbers were very dynamic.

I tend to reset the trip meter on every fill up. I rarely if ever reset any of the Fuel Economy screens. I'll have to double check next time to see if any of those Fuel screens reset based upon me resetting just the Trip#1 screen.

 

[BroncOh]

I finally calibrated my speedometer and used 2800mm for the value in Forscan and did both a PCM and TCM relearn. Used a GPS app to verify and I’m on the bottom side of the rounding which is ideal.

If I set adaptive cruise to 80, the GPS app will indicate at 79 most of the time, and briefly will max out to 80.

 

[Melwinn]

Forscan won’t go to 37s. At least I couldn’t get it to. It tosses up a CEL

I got mine spot on by using 2770 as the outer circumference measurement. Zoodad helped me figure this out in the forscan thread. My truck matches my GPS app speed perfectly. 37x12.5 RT trails. I was originally trying over 2800 and was getting the error as well.

 

[TexanTremor]

I've been wondering the same, and whether there is a setting in engineering/test menu to change.

I seem to be a tad slower by the speed limit signs with radar. If my speedometer is 42-44, the sign would show 40, as an example, as i drive past it by myself.

I haven't done the math yet to translate the speed differences between 35" and 32" tires for the same RPM on, say a 2” axle.

Mine has always been the same. The speed signs are always 1-2 less than my speedo. Which has several negative implications - The lie-o-meter is inflating the milage, but more concerning to me the truck is recording more miles on the odometer than I'm driving, so my 60k warranty is more like 58,500 and it's depreciating faster than it should.