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Hey guys I have a 2011 Silverado 1500 5.3 and 6l80. I had my truck tuned they tuned the transmission and engine. I had the trans replaced and they put the stock gm time back on and the engine still has the modified tune. I noticed when I really get on it there is a little bit of a shudder from 2nd-3rd. It seems like a pressure issue to me. I plan on taking my truck back to the shop so they can turn the transmission back with the modified tune. Should that fix it?
Make sure the shop that put the trans in won't void their warranty. That may be why they flashed a stock tune back in.
I've installed 6L80/09E transmissions both from GM and Jasper. All come with the TCM blank. TCM is bolted up to valve body, do believe it is a part of it. The TCM is loaded with OE vehicle parameters from the GM site, either with MDI or preferred/compatible J-2534 device. Another thing to remember, these transmission are adaptive. You need to put miles on it learning your driving patterns. Hopefully someone else can chime in with an answer about shift adapts related to before and after tuning with HP tuners. My personal experience with these unit is when new/reman and programmed from blank, there will be numerous shifts that can feel funny for awhile. More drive time = better shifts. After about 500-1000 miles, if it is still shifting bad, something is wrong. Learn mileage is probably less, but the 500-1K is my rule of thumb.
I know some 8 speeds have a shudder but you say this is a 6L80 right? According to TSB (Technical Service Bulletin) 18-NA-355, the latest update addresses “torque converter clutch (TCC) shudder conditions on 8L45 and 8L90” eight-speed automatic transmissions, RPO codes M5N, M5T, M5U, and M5X. Affected vehicles include Chevrolet, GMC and Cadillac vehicles. [https://gmauthority.com/blog/2019/08...mment-page-6/]
However, a new fluid flush appears to fix the issues, with some customers beginning to report a dramatic change in shift quality after swapping out the old juice. If the flush doesn’t fix the issue, the next step may be to replace the torque converter, which could be glazed.
The six & 8 speed torque converter is complex and transmission tuning can provide the best bang for the buck IMO.