Tab686

Ok. Did a custom tune to the trans and engine. All I have done to the motor is a k&n filter element. The engine is so much more responsive and runs great. The trans tune was set from locking up in 2nd at 1800rpm wth the factory tune under a light load to late in 4th gear. Also it holds each gear longer before the shifts. What i did notice is once it is in lock up i now know what i was feeling as per the hesitation. If i log the rpm in lockup up a slight hill or any but hold that speed i notice the prm's jump from one number up and down 40 to 60 rpm. Its not a calculation error due to i can hold the rpm in a non lock up situation almost to 0 fluctuation. I emailed black bear and they are going to look into the tune and see if it it calling for 100% lock up or not. I will give updates as they come in. Hope this helps someone else.

Update. Just ordered the Black Bear autocal.. Can't wait!

Ok, I have a 17 3500 chassy cab savana with a reading box,l96 and 6l90. I have the same exact issue since new 40k miles ago. Even with the other member saying in hotter air temps it worse. Even the weird up shifts. My 15 1500 5.3 seirra does this but it's almost un noticable...almost.. I have a Diablo t1000 tunner I use as a gauge pod in the savana. When this issue is happening the ignition timming is low in the. Single digits and fuel trims sometimes go to near 10% negative and positive. Usualy not the 20%full swing.. No knock retard on the gauge. I was thinking its fuel /ignition related...when its runs good. I see great timming and only a 4 to 6 % swing in fuel trims. And no hesitation. The dealer said it was the torque converter slipping in and out 'as designed'. Well he was wrong. He did a live test scan when I was driving and it was in a solid lock up with zero slip while it was happening. Then he had no other comment on the hesitation feeling. Black bear tunning is my next step. They will do a data log and make a tune for the savanna since there is none out there. Anyone have any other updates? Tom