Diablosport Forums

I just started using the intune on my 2011 silverado 5.3 6L80. I previously used it on my old 2007 Yukon. I gotta say, I see a much bigger improvement in the silverado than I ever did on the Yukon. But one thing that's strange is the transmission tuning on the 6L80.

I started out with an 87 tune and a firm shift tune on the silverado, since I always liked that on the Yukon. The ECM side was great but it shifted way too hard from 1-2, knock the breath out of you hard. So I adjusted the shift firmness -2 in every gear WOT. That wasn't quite hard enough. And during that time I noticed a strange flare when downshifting at around 60mph.

So I changed the shift pressure to -1 in all gears WOT. The shift firmness is almost perfect for me. It'll chirp the tires going into 2nd, but it doesn't snap your neck.

Now...the WOT downshifting at 60 is still strange. It acts like it goes from 6th and is halfway into shifting into 2nd and decides at the last second that 3rd is a better idea. So I can see the tach move during the downshift from 1500 up to almost 5000 then it falls to 4200. I feel 3rd engage at 4200 but I don't feel any gear engaging when it flares up to 5000. This all happens very quickly. You could even say it's like it goes from 6th to neutral to 3rd and hangs out in neutral for a couple milliseconds too long.

I've only put 10-15 miles on the -2 and the -1 tunes so should I drive it for a while and let the transmission do some "adaptive learning?" Or should I zero out the firmness in 3rd through 6th at WOT?

Thanks for the help.

If you'd like, email me the tune files from the intune drive.

zhill <at> poweteq dot com

Here's the tunes. I sent them via email also. Whichever is easiest for you.

I changed it to a stock TCM tune and the problem is now happening at 75. I've figured out its happening in 3rd gear. It didn't do it when it was all stock so I'm thinking something between the ECM and TCM isn't gelling.