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      04-27-2010, 06:47 PM   #81
mixja
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Drives: 2011 E90 DCT Silverstone
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Location: Beverly Hils, CA

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Quote:
Originally Posted by niqui View Post
mike,
is this feature unique to powerchip ? or are all big tunes like this.
I am asking because I understood that the dealer could never tell unless the limiter was changed or smthg, but AG could always tell if the ECU was shipped or if they checked algorithms and more in depth - in terms of a large warranty claim.

I know its a risk and the price to play, but I was just wondering if anything has changed since I first looked into doing this.
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)...

Last edited by mixja; 04-29-2010 at 01:22 AM.