PCM is picky
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Senior User
Joined: Apr 2008
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From: London, Ontario
PCM is picky
Okay so here's the skinny. I swapped out my 3.08 open read end, for a 3.55 LSD, no problem. As to be expected the speedo is now way off, no problem either. So I took it to the dealership where my friend works and got it hooked up to the computer to change the programmed gear ratio. We tried inputing 3.55 and it said it was outside normal parameters, and we could choose anything between 3.08-3.10.
Weird. He said it could be that a 3.55 was not available with standard tranny for 2002, mabye? So we tried screwing around with the tire size to equalize it but it wouldn't let us change that very much either. We got it closer but its still not great. Besides I would like to have an accurate speedo going past all the speed traps on the highway. So what are my options? Programmer? Seems like alot of money to spend for a few kph? 
Weird. He said it could be that a 3.55 was not available with standard tranny for 2002, mabye? So we tried screwing around with the tire size to equalize it but it wouldn't let us change that very much either. We got it closer but its still not great. Besides I would like to have an accurate speedo going past all the speed traps on the highway. So what are my options? Programmer? Seems like alot of money to spend for a few kph?
Posting Guru
Joined: Dec 2005
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From: Mount Juliet, TN
Darrin, I know from other boards that you are a very valuable resource to us Fords guys with 4R70Ws and other trannys so could you explain what your solution would be.
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Joined: Jul 2008
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Flashing the processor for the change is the best way to get it done. Without getting into details, please, it is best to say that IF you can find someone with the right equipment it can be done for less than many other solutions when it comes to making such a minor change.
Otherwise, I have to tell you that it would be best to go to someone like Troyer Performance or similar that knows trucks very well and get a programmer.
Maybe you could get a used pre-programmed device that has that functionality for your processor code. I know you can do it with the SCT devices, but I am not sure if a Superchips 1715 would get it done or not. You can find those 1715's pretty cheap on ebay though and if it didn't work for your needs you could probably resell it for what you have in it if you do it right.
Darrin
Otherwise, I have to tell you that it would be best to go to someone like Troyer Performance or similar that knows trucks very well and get a programmer.
Maybe you could get a used pre-programmed device that has that functionality for your processor code. I know you can do it with the SCT devices, but I am not sure if a Superchips 1715 would get it done or not. You can find those 1715's pretty cheap on ebay though and if it didn't work for your needs you could probably resell it for what you have in it if you do it right.
Darrin
