Transmission Tuning Without Shift Pressures or Torque Management Tables?
I have a Whipple SC'd 5.7L '13 Tundra. It has been tuned by a reputable tuner and runs great, but the transmission has always been a little clunky. When I say always, I mean ALWAYS - since the day I bought it new off the lot in 2013. It has been very reliable and tows and hauls often. But when trying to tweak the transmission a little bit, I've not been able to achieve satisfactory results. I've pretty much forum-stalked @SlowNStock for the last six months and have made perceptible changes to one of the tunes that I am able to modify, trying to follow his guidance.
The stock tune that is pulled from the HP Tuners server is missing the Shift Pressures and Torque Management tabs in the Transmission settings.
Basically, here is what I'm running in to: in order to achieve a smoother shifting experience, I can raise the RPM vs Accelerator Position under shift scheduling for each of the gears. But that makes the truck drive like it's working a little harder than it needs to as the RPMs start to level out and almost hang a little before shifting, or the transmission is being lazy and not shifting quickly. It does achieve a smoother shift as the motor RPM's aren't climbing as much under load when it does shift. But it feels lazy.
In an effort to make the truck feel a little less labored and perhaps find a little better MPG in town, I've tried reducing the RPM vs Throttle angle tables (Throttle angle remains the same, RPM is reduced) by 5-10%. The shift points feel more natural, like the engine isn't revving more than necessary, but they get rougher and clunkier. I've also changed the lockup on 4th-6th to lockup a little sooner (4th doesn't usually lock up in normal driving, but it does in AI/Cruise, so I simply copied that shift schedule), but that doesn't affect gears 1-3. I've also played with the downshift tables but approximately the same percentage - 5-10% - but adjusting the Throttle Angle this time while the RPM remains constant.
Several of the guys over on Tundras.com have been gracious enough to try and help me figure things out, but I though I would quit pestering them and bring some of my questions over the forum here. For reference, I've installed shift kits in several older Ford and GM vehicles and consider myself fairly mechanically inclined. Still, I understand that I don't know everything so I'm willing to learn.
I also have a '15 Sequoia and have compared the stock files of two vehicles; they are nearly identical with two major exceptions - the throttle mapping (the sequoia is neutered and dull compared to the tundra) and the transmission tables that are missing on the tundra. Even before the SC, they drove like completely different vehicles. The tundra felt stronger and more truck like, the sequoia drove like a relaxed old man's car unless you REALLY put the pedal down. Shifting in the tundra is more positive - sometimes abusive at WOT - like your rowing gears in a manual with somewhere to be; the sequoia felt like a leisure drive, gently letting out the clutch and rev matching each gear.
I guess my big questions are: how much can I really do without the Shift Pressures and Torque Management tables on the tundra? Am I really missing out by not having them? And ideas why they wouldn't include that with my ECM calibration? ECM is Denso 992k, OS 30CJ64 on the tundra. OS 30CG32 on the Sequoia, same ECM. Any help would be appreciated.
