Speedo calibration & shift points.
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Speedo calibration & shift points.
Hey guys, I just picked up a new set of wheels and tires. They're take-offs from a 2019 F250 Platinum with Michelin LTX AT/2s, at the price they're going for its like almost as cheap as buying good tires. So issue now is my speedo is off. I have several technologies available to me including Ford IDS, AutoEnginuity (w/ Ford pack), and SCT Livewire TS+.
1. My understanding is Ford IDS is the correct tool to use to change the speedo. I also hear that AutoEnginuity can also perform this action.
2. My understanding is SCT Livewire TS+ will only correct for shift points. I do have a tune loaded from my SCT tuner obviously.
So my question is, do I want to use Ford IDS to make the correction for the speedo then use the SCT Livewire to correct the shift points? Is that all in as-built data? Or do I need to re-flash for the shift point correction after making the speedo correction? If it's all as-built data should I do it all in the Ford IDS or does it not do shift points?
1. My understanding is Ford IDS is the correct tool to use to change the speedo. I also hear that AutoEnginuity can also perform this action.
2. My understanding is SCT Livewire TS+ will only correct for shift points. I do have a tune loaded from my SCT tuner obviously.
So my question is, do I want to use Ford IDS to make the correction for the speedo then use the SCT Livewire to correct the shift points? Is that all in as-built data? Or do I need to re-flash for the shift point correction after making the speedo correction? If it's all as-built data should I do it all in the Ford IDS or does it not do shift points?
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Thanks Mark! Easy enough then. What does the SCT Tuner do with its setting? I was told by someone it's something with shift points, but they might be wrong of course. Or does it just not apply to this 6.0?
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,717
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From: SE Florida
I've never used an SCT tuner. I have no idea what it can and cannot do with it's setting.
I developed the stock tunes in these trucks when I worked at Ford. Tire size doesn't make any difference to the shift points. The trans shifts from the reading from the vehicle speed sensor, but it's really shifting from output shaft speed as calculated off of the VSS. Tire size doesn't change the output shaft versus engine speed equation.
I developed the stock tunes in these trucks when I worked at Ford. Tire size doesn't make any difference to the shift points. The trans shifts from the reading from the vehicle speed sensor, but it's really shifting from output shaft speed as calculated off of the VSS. Tire size doesn't change the output shaft versus engine speed equation.
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Mark,
I wound up just changing it with IDS module programming like you suggested, speedo seems bang on with the gps test I did. Super happy how that came out.
As for the tuning I don't doubt you at all, it makes sense to me the OSS is used. I was just wondering why a bunch of posts were talking about that tuner feature. I thought maybe it was more like they were adjusting shift points to optimize for the change in gearing (disadvantage in this case) or something like that. I might give em a call and see if they can explain what the hell it does.
I wound up just changing it with IDS module programming like you suggested, speedo seems bang on with the gps test I did. Super happy how that came out.
As for the tuning I don't doubt you at all, it makes sense to me the OSS is used. I was just wondering why a bunch of posts were talking about that tuner feature. I thought maybe it was more like they were adjusting shift points to optimize for the change in gearing (disadvantage in this case) or something like that. I might give em a call and see if they can explain what the hell it does.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,717
Likes: 2,643
From: SE Florida
Actually, the PCM uses the VSS, not the OSS for shifting. It does a quick calculation to get output speed.
Most people still think you need to change shift points when you change tire size. I don't know why this persists, it isn't true.
Most people still think you need to change shift points when you change tire size. I don't know why this persists, it isn't true.
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Thanks for your insights, definitely appreciate it. Yea I'm not sure what the issue is with the whole shift point thing, but what you're saying makes sense. I tried to call up SCT but their line was saying they're at a staff meeting half the day and then when they did start taking calls no one called back through their call back system. Oh well, might try another day. Still curious about what it does, the manual is so vague about it.
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Lead Driver
Joined: Dec 2006
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From: So. Jersey
My SCT handheld tuner permits you to change Revs per Mile of the tire to calibrate speedometer. Mine had to be set to 689 revs per mile for the speedo to read correctly.
Separately, it also allows you to change + or - % of each gears shift point.
Then finally, in another setting it allows you to also change each gears + or - % of pressure change for each gear.
This is from what I remember seeing when changing custom tunes.
Separately, it also allows you to change + or - % of each gears shift point.
Then finally, in another setting it allows you to also change each gears + or - % of pressure change for each gear.
This is from what I remember seeing when changing custom tunes.
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What problem are they be trying to solve using this inline Speedometer calibrator for larger tires?
https://www.roughcountry.com/speedom...sid=4dRSQCTEl4
Mountain Pass
Joined: Aug 2019
Posts: 167
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From: Miami, FL
To calibrate/adjust the speedometer I used FROScan (free version works). You just change the revs per mile parameter in the ABS module (in programing mode). I have 34.4" diameter tires and a setting of 620 and the speedo is dead on (eve though the implied revs per mile for a 34.4" tire is more like 587. Don't know why, but 620 works for mine.
Laughing Gas
Joined: Mar 2019
Posts: 947
Likes: 144
From: Columbus Ohio
My SCT ITSX did NOTHING to change the speedo. I've changed it 5 times so far and the speedo is always the same amount, gone 100 revs a mile difference each time without any change. Love my tow tunes from 5* though with the throttle response, extra power and trans shifts! I always use my 50HP tow tune.
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