View Single Post
      04-29-2015, 06:37 PM   #18
GSR Technik
First Lieutenant
GSR Technik's Avatar

Drives: F13 M6 | E92 M3 | '15 Mustang
Join Date: Jul 2014
Location: Anaheim, California

iTrader: (0)

Send a message via AIM to GSR Technik
Originally Posted by Thescout13 View Post
How does that work? So the dealer cannot see an ECU tune? Excuse my ignorance I just don't get how that works.
So it's not being done through the OBDII port which a lot times has counters on how many times the interface has been used to load something new.

It's done by plugging directly into the ECU using tools that are derived from the tools that are used to develop the systems, such companies as Siemens or Bosch. The code in raw state is a bunch of binary so these tools allow you look at the code and make changes to the binary that is interpreted by the embedded systems (hardware/software). There is a checksum that gets calculated from the binary to check to see if any of the binary code has been changed. These checksums need to be recalculated if you make any changes to the binary code - these types of tools allow you to do that.

So when dealers are plugging into the cars for general diagnostics they aren't designed to look at the binary directly and say this fuel map has been changed from what is expected.

That's at least the basic idea. There are empirical things anyone could do to test like check to see if the car will go faster than the speed limiter or monitoring boost on a dyno to see if boost is exceeding factory specifications but typically dealers are not doing those types of things.