VIN mismatch

Hello, new tuner here with my first problem. I did lots of searching and found similar issues, but couldn't really find a solution. I currently have the MPVI3 with 2 credits that I purchased for my new to me 2002 Z28. I read the "stock" file today and to my surprise it came up with the VIN for a 1999 Pontiac TransAm! No idea if the computer is from the T/A, or if it was tuned using a T/A file (checked with previous owner and he also didn't know).

So, looking at the Change VIN option, it shows the "Invalid VIN/OS Pair error" which makes sense due to different years/cars/makes/etc.

It seems I need to get the OS back to a 2002 Camaro. Is below what I should do?

1) Download a stock tune from the web site for a 2002 Z28 (there are several posted)
2) Write that tune into my PCM (which I assume will use my two credits)
3) Use the VIN Change tool to change to my actual VIN
4) Read the stock tune file back out (which should now have my VIN)
5) Make tuning changes as desired using new file(will this require two more credits?)

Is this the correct approach or is there a better method? Is this safe to do? I currently have two credits, will I need additional credits to perform this?

Thanks for any advice!

You will need 2 more credits. 2 for the file in the PCM and 2 for the file you want to write to it.

have the ecm flashed to the vin/os pairing you want via tech 2 or similar oem style flash device, then simply read, license & tune away.

You should NOT be flashing someone elses file to your vehicle.

Thanks for the replies. May I ask why flashing a stock tune from the same car with the proper OS should not be done? This would certainly be easier for me as I don't know where I would go to get a reflash (pretty sure dealers around here would not do this).

Quote:

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Originally Posted by dkvan

Thanks for the replies. May I ask why flashing a stock tune from the same car with the proper OS should not be done? This would certainly be easier for me as I don't know where I would go to get a reflash (pretty sure dealers around here would not do this).

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In some vehicles, HPT doesn't use read/write all of the segments of the file (on GM gen4 they are the accelerator/throttle segments) so mismatches can happen. GM Gen 3 writes like this are done but HPT recommends against as a general rule. And although the repository tunes are supposed to be stock, I don't know if that is 100% true.

A few reasons not to.
a. it uses additional credits oftentimes more than the 2 & 2 mentioned by our other forum member above
b. you don't know the history of the file, sure it may say its stock but thats not always the case, if even just 1 byte is off in the cal you do risk bricking your ecm
c. because we say so over and over and over again so its wise to take our advice. Always better to take our advice now rather than have to contact us later because something broke

Ok, great information and will hopefully be valuable to someone else as well. I will look for someone local to help with a reflash. Thank you all!!!