Going back through saved history logs in a 2007 Trailblazer SS I've been working on over the past month while he got motor issues sorted out, and on one I see Operating System - Code Modifications - Speed Density 2 Bar and have a major WTF moment as I never changed it to a 2 bar OS (it's a n/a 416ci). Go to the OS section, and it still says Speed Density - 2 Bar and has the button for "Apply Code Modification" like normal for any file that's still on the factory OS. Keep looking through different history saves and out of 24 total saves, 7 of them say that the code was changed to a 2 bar OS. So now, going back and looking at tunes I've done since I started working on this TBSS, there's 2 2010 A6 Camaros that did it, a 2010 M6 Camaro that didn't, 04 Silverado that didn't, 2014 A6 SS (the 4 door) that did, and a show truck with a 2010 A6 Camaro pullout that didn't.

So the issue has shown up on 2 different PCMs (one E67 and 3 E38s) and all 4 instances of it that I've found are running different factory OS numbers. All done with 4.0.12 software.

Honestly, I don't know if it's affecting anything or not. The SS had a few quirks, but I figured that had more to do with the ported throttle body and intake manifold done by the owners friend than anything, and the Trailblazer is a 416ci with a big cam (240s/250s duration), LS3 heads, Escalade manifold, and 102mm throttle body so I knew it wasn't going to be a "normal" tune anyways.

Anybody else seen this happen? HP Tuners guys, anything y'all want to check or have me send in? I leave for SEMA Sunday afternoon, so I won't have access to any of the vehicles for a week, but I'll have my laptop with me.