What did you do to your NNBS GMT900 Tahoe/Yukon Today?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

m1dn

Full Access Member
Joined
Jun 15, 2022
Posts
178
Reaction score
316
Update after a week with predator 93 tune and raising idle/parl rpms - i can’t believe how much smoother the car drives, not a single vibration when idling, takes off super smooth and rough shifts are gone.

Think I’m going to add tuner to my must have/do list on any older used car in future.
 

the_tool_man

Full Access Member
Joined
Oct 15, 2018
Posts
750
Reaction score
1,713
Location
Upstate South Carolina
Had a productive conversation with the transmission guy I'm going to use to repair my Yukon. He called around and found a GM reman 6L80 with heavy-duty upgrades (valve body, solenoids, I/O shafts, etc.) in stock at the local GM dealer. He said they typically take a month to get, but we got lucky. Going to add a pan with a drain plug. Also changing transfer case and diff fluids, new radiator (cooler undoubtedly is full of debris), and for good measure going to add an auxiliary cooler. I'll lose whatever TCM tune BB did. But this guy has a dyno, and tunes transmissions. He said the HD 6L80 will probably make me happy as is. But after break-in, he'll make any adjustments I want for free. I like this a lot, because while the BB tune was a game changer, I wasn't entirely happy with the 2-1 downshift being so harsh. It'll be good to have someone local I can take it to for tweaks. Besides, now that BB doesn't honor their lifetime tunes, I've got no loyalty for them anymore. This whole thing sucks to be happening when I'm in the middle of moving. But I'm glad to be fixing this right, getting a bit of an upgrade, and getting some overdue maintenance done.

First question: what cooler should I get? I see recommendations for several.

Second question: the transmission guy says lots of tuners jack the line pressures up and kill the pumps early in the 6L80. He said he'd look at the BB tune to see what they did. But he thinks that might be why it died at 140k (tuned since 99k). I've never heard of a BB tune killing a trans. Do you think there's any validity to this? I wouldn't be so quick to blame BB. If anything it's an indirect cause, as my right foot would have had a lot to do with it.
 
Last edited:

Forum statistics

Threads
132,151
Posts
1,863,159
Members
96,651
Latest member
bigtoe
Top