Originally Posted by mixja
I had this explained to me quickly a while back so the details may be wrong, but I believe that all ECU map files are digitally signed using similar signing/encryption techniques as digital certificates on web sites.
So in theory this should stop the ECU reading a map file that has been modified - however the BMW ECU only checks the digital signatures when the ECU maps are written to and either the ECU only does this if the maps are written in full, or there is a special flag you can set when programming the ECU that disables this checking (it may be a combination of both).
I think the BMW dealer tools probably only check signatures are valid and that the ECU has not detected any unknown programming changes to the ECU. The ECU only records "complete" programming changes - i.e. an entire software package or set of packages (like how the dealer does it) was written to the ECU, and does not record smaller incremental changes (like the one Powerchip does).
I certainly would believe it is possible for BMW to detect the change if they really wanted to, but it is a question of logistics, cost etc (e.g. do they have to send the ECU back to Germany)...
I believe the mechanism Powerchip uses is the same as every body else - or at least everyone that uses CMD Technologies who provide the tool that I used to flash my Powerchip tune...
thanks for all the info...
still seems like a very very slight gamble.
do you think it is kind of stupid to tune without a cat delete? cause i dont want the car any louder, even hfcs plus xpipe can kinda add sound and drone, i know some dont but still....all i have is pulleys, envy intake, catback.