i have got a 04 6L diesel. when you use a programmer can the dealership tell that there was one on there or does the computer hold its origanl setting once you unplug it. is there only some programmers that can store the origanl settings so you can always unplug it and everything is factory warrenty OK.

 

I think the factory could probably tell you all about it. I think I saw a company making warranty compliantdeals that are OK with the Ford warranty. It never hurts to ask your dealer. Sometimes you'll find they aim to please. If I am wrong on this - as long as you can disconnect the non-compliant system and plug the old one back in without cutting wires (and then unplug your battery cables to reset the computer) you should be OK.

 

According to my dealer when I bought my 2006 6.0, they told me today's new computers will tell them everything.
They will know what date, what time and what all you do to the truck that is computer based and you can remove everything but the computer will remember everything. It actually burns it into memory and you can't erase it. Whether this is real or false information I do not know.