4L60E tuning in $0D

[Roadknee]

I looked through several of the $0D bins. In general the V8 bins are similar and the 4.3 V6 bins are similar to one another. Unfortunately there was not a performance application that used $0D for me to try and learn from. I spent a little bit of time experimenting with the above tables, but not enough to draw any conclusions. More on that later.

I've made several changes to upshift/downshift mph vs tps vs gear tables and the TCC lock and unlock tables. I have it rev a little higher before upshift, downshift sooner, engage TCC later and disengage TCC sooner for a more performance oriented feel. Much of this is personal preference.

The biggest improvement was locking the TCC in third gear. With the stock BJYL tune, the trans upshifts to 4th at 29 mph under light throttle and never locks the TCC in third. The TC slips considerably when running around town at 35 mph in fourth gear. I delayed upshift to 4th under light throttle to 44 mph and engage TCC in third at 32 mph. It feels a lot better now and takes considerably less throttle running around town.

I also set the Lower Low Speed TPS and Upper Low Speed TPS to Prevent TCC Cycling to 0% to keep the TCC locked on deceleration at 0% TPS. As long as MPH is below the MPH for Using Low Speed TPS Thresholds the TCC will remain locked. I temporarily set the Low MPH to 84 and high MPH to 86 for a test. The TCC would remain locked on deceleration in fourth gear, and it behaves like a manual trans. In third gear, the TCC appears to remain locked, but the trans shifts to 4th at 0% TPS. It loses a little rpm on deceleration. As soon as I touch the throttle it returns to 3rd gear TCC locked rpm. If I pull the shift lever into third gear, it stays in third and the TCC stays locked on deceleration, and it behaves like a manual trans. I searched through the BIN, but couldn't find any way to keep the trans in 3rd gear during deceleration with the selector in fourth gear.

There are a second set of parameters, High Speed TPS to Prevent Repeated TCC Cycling. As long as these are populated with positive numbers, the TCC will disengage on deceleration when the actual vehicle speed is above the Upper and Lower MPH for Using Low Speed TPS thresholds. I set these to 46 and 44 mph, respectively. Thus, in 4th gear and above 46 mph, the TCC unlocks on deceleration. I didn't care for the feel with it locked in fourth during DFCO. It really slows the truck down.