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Transmission tuning observation

Old Sep 26, 2010 | 11:45 AM
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Default Transmission tuning observation

Truck is 2002 Z71 w/stock 373 gears, stock 4L60E w/stock converter, stock height tires (31's), and what I'd consider lightly modded...longtubes, homemade cold air w/stock airbox, ported throttle body and tuned by me via HPTuners. I have a Vette servo, but just have never made/took the time to install it.

I've used some great tips from Russ K (HPTuners site) regarding dialing in shift pressures, and adjusted mine accordingly. I had also played around with TCC lockup speeds and PT shift settings, but the lockup and PT shifts never seemed "right" to me. Always seemed to be shifting up and down under loads, up hills, etc...

WOT upshifts and downshifts are, and always have been great, since tuning.

After dialing in my WOT shifts to my liking, and so that there was no more 60-70mph "dead zone" when merging, I did what most threads/opinions I read said to do, which was match my 100% tps "MPH" Part Throttle settings to my WOT MPH settings. I did this months ago and interpolated the entire PT mph upshift/downshift MPH's so that they matched WOT at 100% TPS in the Part Throttle cells.

After driving my son's 100% stock (aside from catback) 04 Avalanche to work a few days, I really liked the way his shifted when driving "normal", which is what I do 99% of the time anyway.

I decided to try something on mine, which was to leave all WOT upshift/downshift, torque reduction & shift pressure changes alone, but swap all PT MPH and TCC lockup/unlock settings to stock.

So far I am very pleased with how it runs/drives so far. It seems to accelerate and get up to speed quicker at light throttle now, I guess because it's upshifting alot sooner and not winding out the gear like it has been for a long time.
Passing/merging is still great since WOT "tune" is untouched. It will downshift (from Drive or OD) to 2nd gear as high as 72MPH, and Drive or 2nd gear to 1st gear at as high as 38MPH, which basically lets the RPMs jump up to near my maximum RPM (of 5600) long enough to upshift with some semblance of momentum (43MPH into 2nd & 76MPH into 3rd @ WOT)

PT driving, the upshifts and downshifts are stock, except for slightly higher shift pressures. Enough to firm it up as RPM rises, but nowhere near harsh or clunky. Perfect match for my driving style and truck usage, which is as a truck, not a drag racer...although I have been known to "speed" next to others on occasion, lol.

I always thought that the recommendation for PT 100% TPS shift speeds matching the WOT shift speeds was kind of redundant since there really isn't a 100% TPS Part Throttle anyway. I mean 100% TPS...isn't that WOT?

Just wanted to share...your results may vary.
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