GM Event Recorder...End of Tuning???

[RWTD]

if the factory calibration is installed the CVN will be correct.

Chris,

This was posted last month on CF:

I can tell you that as a proud owner of a TECH2 and using various tuning tools to tune hundreds of GM cars and trucks, the CVN ID numbers are NOT changed. This is because I change only the constants in the PCM program and not the actual OS. If I choose to install some kind of custom OS such as a speed density tune from HPT or a 2 bar calibration then yes, the OS will be changed and then the CVN numbers are ALTERED, but if I just read what is in the PCM and change it, the CVNs are also NOT ALTERED. I can't speak for EFI Live, because I have heard that EFI live does inherently change thing the OS, as did a early version of LS2 Edit which LOCKED the PCM upon a write, what POS that program was!

And this was just posted on CF as a follow up (reading the link quoted below is interesting, needless to say):

Bringing this one up a bit since I've spent the last few months working on this. ANY change to ANY area of the calibration will result in a change in corresponding segment CVN. There is a CVN for each segment of the cal including the OS. The CVN is not hardcoded its calculated everytime its requested, so its not something that can be changed and then rewritten and if you try to mess with it it will fail CRC AND CVN checks (unless of course you read the link below )

So short version is if you have a tune yes the CVN is different... If you want to keep your tune and be 100% undetectable you might want to read this

http://www.g8board.com/forums/showthread.php?t=4684

Your thoughts?

[Chris@HPTuners]

if anything in the OS or Calibration is changed then the CVN must change unless it has been disabled. On some PCM's it can be disabled on others it cannot.

On most newer GM PCM's the CVN is used as the ROM checksum, so if it is not correct the PCM will not run. Again unless it has been disabled.

[RWTD]

More info that was posted tonight by tjwong:

Well, being that you are a junior member and that this subject has been BEAT TO DEATH, and I really do hate to disagree, but what you are telling people is total BS. Attached here are pictures of my TECH2 showing the CVNs in my personal Z06, most everyone here knows me or knows of me and knows that my car is HEAVILY modified. If you look at the picture of my TECH2 it will show the CVNs that are in my car, also attached is a screen shot of the ACTUAL GM SPO website that depicts the correct CVNs for my car. If you look at the pictures you will see that the CVNs MATCH PERFECTLY. My car was tuned with HPT, now if you use a special NON FACTORY HPT 2.5bar calibration then the CVN for the engine OS will definitely NOT MATCH. But for all intents and purposes, for all but the most heavily boosted Zs, the stock GM MAF cal can be tuned for 99% of all cars out there with headers, head and cam packages and most mild boosted applications.

There is NO WAY a dealer with their standard scan tool which is the venerable TECH2 will see anything that has been modified, that is unless you use a special NON GM cal from HPT or EFI Live. They are NOT using their new MDI interface for anything other than programming PCMs at this time, in time it will replace the TECH2 but not for at least 2 years. Also if GM really wanted to see what you done to your PCM, in case of a catastrophic failure, all they need to do is to send your PCM back to GM PT Engineering. A friend of mine is a very close friend of the president of GMs powertrain division, he was qupted as saying that in some cases because of possible warranty fraud this can and will happen.

I hope that after seeing this answer and the attachements that this will put peoples mind at ease. I DO NOT ADVOCATE warranty fraud in any way, this is just to clear the air, and or this thread......

[Chris@HPTuners]

the guy is confusing the CVN with the Calibration ID.

CVN for each segment Cal ID can be seen for later vehicles on GM's website.

[Texsrt4]

chris where did you learn all this stuff and where can i go to be as smart as you? seriously now, what classes do you take to even get close to this stuff?

[Chris@HPTuners]

chris where did you learn all this stuff and where can i go to be as smart as you? seriously now, what classes do you take to even get close to this stuff?

i watched a show on the discovery channel once... no seriously...

it's a lot of hard work that basically starts with wide eyes, a binary image from a flash chip, a disassembly program (such as IDA) and a LOT of time and caffeine. you need skills like basic hardware knowledge, assembly and embedded CPU level features, logic and understanding of engines & transmissions etc. Also writing code in C/C++/C# helps. It also helps a lot if you understand how compilers work at a low level.

good luck trying to find some place that teaches this stuff!

[Texsrt4]

unfortunately it seems like most things in this industry are a learn by trial/experience. thanks for the info though, it definitely points me in a direction

[Bandit gs]

Glad someone understands it the inner workings, I had to take C++ in college for an engineering degree and cheated my way through it, hated that class

[NGalaxyTimmyo]

When I blew my engine with only 30,000 miles on it I didn't even think to take it into a dealership (well, maybe just to see their face. I pulled the blower off my car and put a GT30 turbo on)

I got a new engine and put it in myself with help from some friends. Learned a lot that way too

[jakebdb56]

You could just fry the PCM and CVN modules before you take it in for warranty