Change gear ratio 3:73 to 3:55 in PCM

[TexasRebel]

OBDLink MX Scan Tool.

About $80 retail price, available on Amazon or anywhere else similar.

Yeah, that's the one I have, too. I like that it doesn't have a HS/MS CAN switch.

The only tool I know of that will easily change the rear-end ratio in the PCM is the Ford ProCal tool. As far as I can tell, FORScan doesn't have full access to the PCM. I have the FRPP Power Pack 2 which came with a ProCal3... It allows me to change from some ridiculously tall ratio down to 4.09:1.

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[Wolverine]

As far as I can tell, FORScan doesn't have full access to the PCM.

You may be more correct than you thought, at least as far as the PCM goes.

Forscan has a fair bit of control over the BCM because, just like your Ford ProCal tool, it can change the rear axle ratio to virtually anything including 4.09. That wasn’t the issue when I was using it. It was trying to force the PCM relearn (to adopt the changes as the new default settings) where I felt that Forscan lacked the power to get the job done.

 

[Nghtshd88]

Just swapped in a TR3160 trans and having this same issue but no limp mode. Just power loss in 4th gear at 2k-3k rpm. Is it possible to change trans ratios in the BCM?

 

[Rickloreto]

Just swapped in a TR3160 trans and having this same issue but no limp mode. Just power loss in 4th gear at 2k-3k rpm. Is it possible to change trans ratios in the BCM?

I had the same issues in my 18 a10 mustang everything got corrected with both tire/axle ratio changes then doing pcm relearn clearing the p code along with the adaptive learning table reset so it learned everything off the pbd tune. Normally they set the rollout circumference between both regular and the drag tire in my case right in the middle since the module can only account for a 3% change in size without issues so essentially if the tire size is out more than 3% it will cause limp mode feel, shifting issues etc unless thats changed in the tune based on what you do with the tires. Ever since no clunking/limp mode feel in any gear as well as crisp way faster than stock shifts like if they are instant already in passing gear already. Quite amazed by how these changes make the cars feel like a million bucks! Hope everything was resolved since for you guys!

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