Hello, I am having intermittent issues with my 2012 Yukon that has a 6.2 swap. I start out in manual mode in 1st, then immediately put it into drive after punching it. Most of the time this works great, but occasionally the shift gets messed up where it will act like it will go 1st to 2nd, then back to 1st (the revs fly up) then back to 2nd again.
I have attached a log where it is doing that. Right at 17:34 is where it's about to shift to 2nd. The RPMs drop to 4100 like it shifted, but then immediately you see the RPMs spike back up to 6400 (like its back in 1st gear) where it looks like it attempts to shift again and completes successfully. It never does this from a normal in drive 1st to 2nd shift, only when I am in manual mode first and then swap it over to drive so it auto shifts. Is there a better way to accomplish my rolling starts?