I recently had a full freeflow system fitted to my Opel/Vauxhall Astra Turbo Coupe. Along with this, I had a stage 1 STO map done to take full advantage of the new exhaust characteristics. At any rate, I asked the tuner whether I could use the Torque Pro app I had on my Galaxy Tab to read boost, temperature, timing advance, etc from the OBD port like I did before. He said that attempting this would corrupt the map. He also stated that the STO software he flashed to the ECM would report false readings.

Now, I know the answer is reasonably obvious to someone who is a software developer and knows a bit about the OBD protocol, but rather safe than sorry. It seems the guy thinks I want to reverse-engineer his map and sell it or customise it even further, so talking to him is like talking to a brick wall.

So basically:

  1. Is it possible to make the STO software (or any software loaded onto OEM ECU's) report false readings on the OBD port?
  2. Can the STO software (or other software) be used to trash a map if it detects communication on the OBD port?

I never had issues with reading stuff from the OBD port when the car was still standard.

3 Answers 3


In my opinion, most of the stuff he told you is bullshit.

First off, he didn't install any software on the ECU; he just dumped the original firmware, identified where the values that control fuel injection are (amount of fuel, etc), changed them and installed that modified firmware; in the end he just modified a few digits in the original code, nothing more.

To do what he told you he'd have to completely rewrite the code that handles OBD communications, which is specific to each ECU, proprietary (no source code at all, good luck reverse-engineering the assembly code that you got from that ECU) and extremely hard to do if doable at all (not to mention risks, imagine the danger if his buggy software suddenly crashes and your engine goes on full throttle).

Now, feel free to connect your diagnostics adapter, no need to fear anything.

Oh and if you want to reverse-engineer his map, just unsolder the engine ECU's ROM, poke at it using a hex editor, find where the actual "map" is and there you have his precious "map" (you may want to load it in a software like WinOLS); and no amount of software nor bullshit that he tells will change that (to protect against that you'd have to implement encryption in the ECU to decrypt its own data, which is probably impossible on such low-spec hardware, and even then, the key would still be there somewhere waiting to be found by some curious soul).

  • Thanks. I sold the car last week, so I thought I might as well give it a shot. I plugged it in and everything was reading as before, though obviously the boost went higher and the calculated fuel consumption and horsepower/torque displays went a bit higher. Commented Oct 14, 2014 at 6:57

I am a CAN App programmer so I would like to share a bit of my experience.

  1. Yes, you can report false. It's even very simple. Just watch for messages you don't like and then report error. But what is the point to implement such a stuff? Then you will not be longer able to read error or some other parameters by your own.

  2. Also yes, if he is trying to protect his software, but why this way? As a programmer I would do something like backlist for commands like: read/write of ECU data, so the other things like reading and erasing errors and reading parameters could work as before.

The point is, even with modified STO you should be able to read your stuff (with your galaxy tab) like you did before/standard car.

  • Thank you. You have given me all the information I need. Commented Jul 28, 2014 at 10:02
  • 2
    I doubt any tuner would put a logic bomb into a tune, if it is possible at all. Yes, you can get false reports (ie: tune out cat O2 sensors). If I understand the process, the "tune" is just a flat file which is put into static memory. The STO program is just used to create the tune and to get it onto the PCM. Once there, the program has nothing more to do with it. Besides, wouldn't a tuner be shooting himself in the foot if the owner takes his vehicle to a shop to get emissions done and the tune blows-up (figuratively)? They'd have to go to the shop and re-install the map again. Not bright. Commented Jul 29, 2014 at 0:25
  • You're obviously not a South African, Paulster2. It's crazy what people in the motor industry (try to) get away with. I'm not saying this particular guy is shady, because he has a great reputation and I asked for him by name so quite the contrary but there are guys out there who do weird things and get away with it. It's best to expect the worst. Commented Jul 29, 2014 at 7:14

Using 'logic bombs' or other types of 'seeds' is fair and reasonable to protect any particular piece of software from being copied. If software is made easy or open to re-distribute you will find a lot of developers going out of business. The methods you ask in your question point to good ways to prevent the software being lifted.

  • Surely not if it interferes with diagnostic scans? Commented Jul 28, 2014 at 10:13
  • I dont know the extent of protection on your new system. The developer for it may have his own version of a diagnostic app. If the software is commercially sound it will/should be locked. Commented Jul 28, 2014 at 15:35
  • I understand what you're saying. What irritates me a bit is that the software is supposedly "undetectable" by the dealer, yet if it were to misreport or freak out if someone plugs a diagnostic device into it, it would become immediately obvious that the software has been altered. But that's another matter entirely. I simply wanted to know whether it is possible, and as you and Watsche have confirmend, it is. Thanks. Commented Jul 28, 2014 at 15:38
  • What you say is true for real software, but a tuner doesn't write his software, he just dumps the original ECU's software and changes some values.
    – user5106
    Commented Oct 14, 2014 at 2:02
  • @JuannStrauss yes the "software" is undetectable because it's still the original software, just with some modified values; only dumping the image and comparing it with the original one will reveal the modification.
    – user5106
    Commented Oct 14, 2014 at 2:03

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