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Certified Bwaloligisit
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So today I went for the good ole winter start up. The car currently has a custom tune for my cams and other goodies loaded on it. Turned the key and the engine did a few slow cranks before it stopped and the starter began to tick. Dead battery. Now my question is. If the battery dies or is disconnected, dose the ECU revert back to the stock tune? or dose it stay on the loaded tune? I always assumed it reverts to stock, so I always reload it. But I've never seen a real answer as to whether it dose revert or not.

So in short. Dose the ECU reset to the stock tune when the battery dies or gets disconnected?
 

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The tune is stored in non-volatile EEPROM (Electrically Eraseable Programmable Read Only Memory)--it can only be erased or changed actively by reflashing the EEPROM, which requires that 18V be applied to pin 13 of the OBD2 connector.
 

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Certified Bwaloligisit
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Discussion Starter #4
So in English, it's fine and can only be changed via the hand held tuner. So disconecting or dead battery will not have an effect as the same tune dose not change.

Gotcha. Thanks!
 

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Bingo!
 

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The tune is stored in non-volatile EEPROM (Electrically Eraseable Programmable Read Only Memory)--it can only be erased or changed actively by reflashing the EEPROM, which requires that 18V be applied to pin 13 of the OBD2 connector.
expert! reps my man
 

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FWIW and although no one asked, I have seen it put forth on the web and elsewhere that the PCM EEPROM can be "worn out" by excessive erasing and reprogramming.

While this is technically true it is important to know that Motorola specifies the 81Cxx flash memory for up to 100,000 programming cycles. Reaching this number would require flashing a new tune 10 times a day, 7 days a week, for 27.4 years...
 

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Discussion Starter #8
now that Im home and not on the phone...

REPS good sir! You know your stuff
 

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K1w1
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If there's anything Cliff doesn't know about our cars then it's because ford never thought of it!!!
 

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FWIW and although no one asked, I have seen it put forth on the web and elsewhere that the PCM EEPROM can be "worn out" by excessive erasing and reprogramming.

While this is technically true it is important to know that Motorola specifies the 81Cxx flash memory for up to 100,000 programming cycles. Reaching this number would require flashing a new tune 10 times a day, 7 days a week, for 27.4 years...
I was literally going to ask this question. I had always been under the impression that if you let your car sit long enough to where the needles do the sweep on start up, that the tune needed to be reloaded. Which is what I have been doing for the past, oh I don't know, 2 years. Now that I know it's not needed, I will no longer be doing it. Thanks for the info! Reps will be given.
 

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Good to know.I had always thought that if the battery was dead or unhooked for more than 10 min it would revert back. Good to know it wont.
 
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