DragonPL

If for some reason the battery dies does the computer reset it self than and the tunes would have to be re-loaded???

Pyrat

Dragon, while this is a guess, it's based on years of computer nerddom. [sm=smiley1.gif]

The memory used in the computer is most likely some kind of EPROM (Erasable Programmable Read Only Memory). EPROMs are not volatile like the system memory in your home computer. Volatile means when you cut power to it, it loses what is stored there. If the memory in the Mustang's computer was not non-volatile memory every time the battery died on a vehicle so equipped it would not run until the memory was re-flashed (program reloaded). The battery has died a couple of times on my Mustang (sitting in the garage for extended periods) and when jump started it had the custom (XCal2) program intact and ran normally. What you probably do lose is some of the things that the computer "learns" over time about your driving habits. This guess I base on the reset procedure (disconnecting the battery for 15 minutes then reconnecting it). Now again (the disclaimer [sm=smiley1.gif]), this is based on observation and not on any hard data from Ford or other reliable sources (Like our buddies here on MF)

LX200

I believe the tune itself says put... as it is in EEPROM, but any "learning" the computer has done based on your driving style is lost. This is why we can disconnect our battery, reconnect and flash back to stock and the dealer has no idea we were tuned...

rmays06

Great question and info guys!