6L80 - DIY Rebuild - Good for 4000 miles, now first slipping

[chrismec]

Hi all, first post, first 6l80 rebuild and first HPTune.

About 4000 miles ago I rebuilt the 6l80 in a '15 Yukon. She was doing great until just recently. Now, on the very first acceleration, just after starting the engine, first gear engages fine, starts to go, then feels like it slips for a bit, then goes fine for the rest of the drive. As soon as I turn the engine off, then get back in to go, she slips in first for a bit, then goes OK.

Everything was replaced except for the Techm, but when it started acting up, I replaced that too, but had no change. So I bought a HP Tuner and performed the suggested tune from this HP Tuners 6L80 tuning video https://www.youtube.com/watch?v=KhPB7-RWQbY . But sadly, there was no change for the first gear issue.

I have a "post tune" log file at: https://thechristisens.com/publicdoc...PostChange.hpl
I couldn't get files to upload on this site for some reason.

I'm not quite sure what I am looking at yet, and am hoping someone may see something obvious.

Thank you very much for your time! Matt

[chrismec]

The one thing that stands out for me, is the PCS 2 pressure pulsations (in yellow). It only does this after engine start and initial acceleration.

6l80-log-screenshot.png