2008 Suburban K2500 6.0L 6L90 and 35's

[LT4USMC]

As I said in the title I have a 2008 Suburban K2500 6.0L 6L90 and 35's. I'm running the Diablo tune from my inTune but the TCM Shift Points are way off, as it shifts to early under part throttle. If I use the Tow Button in shift the trans in a better pattern but won't allow it to go in to 6th gear. So I click it back to normal on the freeway. The problem is that when I go over and overpass it stays in 6th gear will lose 5-8MPH take about 50% throttle then kick down to 4th gear. I'm a little new to the tuner game but have been reading a lot on the forum. The auto update says my inTune is up to date, so I think I'm good there. I tried getting touch with Lew but as we all know he is down at the moment. So my questions are:

Does anyone have a good starting point for a TCM Tune? ie. + this or - that?
How do I adjust part throttle TCM Shift Points?
Does the Diablo Tune also effect the Tow Button tune?

I'm sure there is someone that has run into this issue as well. I bought this 'Burban last week and would really like for it to run better than it does.

Thanks in advance,

LT-

[mikel]

Is the speedo dialed in for the tires?

[LT4USMC]

Yes Sir

[mikel]

it should be shifting at the correct speed/rpm at part throttle, it likely seems too low due to the weight of the larger tires which need more torque to get up to and to maintain speed.

A custom tune may be a good idea.

[LT4USMC]

With Lew down who do you suggest?

[mikel]

I suggest waiting for Lew