Spart
Well-Known Member
The stories I've heard of this happening have been people that had their dealer upgrade the Sync 3 software.
If they run into issues, I'm sure one of their canned troubleshooting steps is to reset as-built.
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Modifying As-Built Data Guide
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If they run into issues, I'm sure one of their canned troubleshooting steps is to reset as-built.
Glas86
Member
Iam having an issue changing my rear axle ratio from 3:73 to 3:55. I can change it in the BCM without any issue but then get a U0422-2F DTC from the PCM. The PCM relearn procedure does not solve the dtc. When I reset the value to 3:73 the DTC dissapears. Seams like I can not start the PCM relearn properly. Also the dtc seems to be a different one then I would expect.
Iam using a elm327 with toggle switch on a 2017 Mustang GT PP. Might this be an issue with the elm adaptor? Or is there a known issue with the relearn procedure? I also used different versions of Forscan to relearn the PCM without any change.
Is there some one in the Detroit area who could help me with that issue? I would pay for it. Iam not confident enough it is the elm to spend another 80$.
https://www.mustang6g.com/forums/showthread.php?p=2237027#post2237027
Iam using a elm327 with toggle switch on a 2017 Mustang GT PP. Might this be an issue with the elm adaptor? Or is there a known issue with the relearn procedure? I also used different versions of Forscan to relearn the PCM without any change.
Is there some one in the Detroit area who could help me with that issue? I would pay for it. Iam not confident enough it is the elm to spend another 80$.
https://www.mustang6g.com/forums/showthread.php?p=2237027#post2237027
TexasRebel
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What lines did you change?
From what value to what value?
TexasRebel
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I'll have to plug mine in tonight. The only gear ratio mention I remember was on the ProCal tuner I got with my Power Pack.
The u0422 code means your BCM is sending invalid data which leads me to believe you need to change something in the PCM as well.
At the very least, go low-level and find the VIN for a 3.55:1 car that's equipped as close to yours as you can get... Then compare the as-built data from Ford to find everything that changes between 3.73 and 3.55. It won't be as easy as say, 3.31 to 3.55 because the 3.73 means you have a Performance Pack car so lines that don't apply to the final drive ratio will be different, too.
Although, comparing cars equipped identically except for the gear ratio (3.31 v. 3.55) should tell you exactly which lines to look at in both BCM and PCM.
The u0422 code means your BCM is sending invalid data which leads me to believe you need to change something in the PCM as well.
At the very least, go low-level and find the VIN for a 3.55:1 car that's equipped as close to yours as you can get... Then compare the as-built data from Ford to find everything that changes between 3.73 and 3.55. It won't be as easy as say, 3.31 to 3.55 because the 3.73 means you have a Performance Pack car so lines that don't apply to the final drive ratio will be different, too.
Although, comparing cars equipped identically except for the gear ratio (3.31 v. 3.55) should tell you exactly which lines to look at in both BCM and PCM.
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Glas86
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Would be great if you can have a look. I compared a car which is very close but has 3:55 gears. Seams like the main think being different other then tire circumfence and gear ratio is the Vin when I use the first page document from the f150 to decode.
Spart
Well-Known Member
[MENTION=34447]Glas86[/MENTION] are you on the factory tune?
If you're not getting drivability issues with the factory gear ratio setting, you might consider just changing the tire size to correct your speedo. My calculator has a GPS truing function that you can use for that.
If you're not getting drivability issues with the factory gear ratio setting, you might consider just changing the tire size to correct your speedo. My calculator has a GPS truing function that you can use for that.
Glas86
Member
Unfortunately I am having drivibility issues. 4th gear around 2500 rmp there is no torque. Yes Iam on the factory PP tune. Just seems like PP PCM tune just accepts 3.73 gear ratio. I can change the tire size without any issues with the relearn procedure. I do not want to go to a custom tune. Just changed the diff cause I could not live with those all kind of noises the Torsen was doing. The dealer just said that was normal. But with the 3.55 diff now I do not have any thud or noise issues whatsoever. Is there any chance exept a custom tune to adapt the diff ratio. I do not care about the speedo. Ist just 5% anyway. So 5mph at 100mph.
TexasRebel
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Are the nannies on? Does it think you're slipping and start limiting torque?
Speed data should come off of the axle... so it'll be right based on tire size alone. The ring & pinion ratio is used as a feedback loop from the engine/transmission. It either doesn't mean as much for a stick since the car has no idea which gear you are in anyway... or it means a whole lot because knowing the final drive ratio is necessary for the car to figure out which gear you are in to choose a fuel map (more likely) and bad numbers will cause confusion.
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Glas86
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Yes thas what I thought too speed is probably correct since it is measured with the abs sensor but it might be detecting a slipping clutch cause of the wrong axle ratio value. Thats how it feels. Once you above that 100rpm wide rpm band around 2500 in 4th all is back to normal. Unfortunately I can just change tire sizes in both PCM and BCM. The PCM does not accept any axle ratio other that the 3.73 one. Probably there is a PP specific tune which doesn't accept axle ratio changes? Is there any other way then a custom tune to change axle ratio in the PCM?
Glas86
Member
It happens in both scenarios but 3.73 is original without DTC. I would have left it as is if there weren’t these drivability issues. If I change the axle ratio in the BCM I get a Uxxxx DTC which doesn’t resolve with the PCM learning routine. But if I do it with the tire circumfence I get the known PxxxA DTC which resolves with the PCM learning routine. That leads me to believe the PP stock tune does not accept axle changes. At least not in the way it works for most other people.
Spart
Well-Known Member
There is a tone ring that can easily be damaged when doing a diff swap that causes issues.
Please read this thread starting at post 78 by [MENTION=30109]Elit3Sally[/MENTION] : https://www.mustang6g.com/forums/showthread.php?t=67564&page=6
Post 111 would be of particular use to you as well I think.
You might want to post in that thread with details about your issue and experiences so you can pick the brains of people who might still be subscribed to it.
ETA:
Can you explain? I've got the torsen as well, and while it isn't the most pleasant when taking tight turns (like in a parking lot) I do feel that it is a very good diff.
Glas86
Member
I did not have any DTC after the Diff swap. And also all DTCs resolve when I set the values back to original. So I do not believe it is an phisical part issue and that I damaged sth doing it.
Regarding the Torsen... I mainly had the thud quite bad. I brought it to several dealers and everyone wanted me to believe it is normal. I was close to sell the car cause I could not live with the shock going to the drivetrain everytime I shift from 1st to 2nd and 2nd to 3rd. My wife refused to drive the car because of that. Now that issue is gone but I can’t reset the axle ratio. Maybe I have to go the route and get the backlash properly set in my original diff then. Probably the last Ford I buy...
Regarding the Torsen... I mainly had the thud quite bad. I brought it to several dealers and everyone wanted me to believe it is normal. I was close to sell the car cause I could not live with the shock going to the drivetrain everytime I shift from 1st to 2nd and 2nd to 3rd. My wife refused to drive the car because of that. Now that issue is gone but I can’t reset the axle ratio. Maybe I have to go the route and get the backlash properly set in my original diff then. Probably the last Ford I buy...
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