4L80e swap harsh part throttle 1-2 shift?

[SilverBullet6.0]

I?m having an issue with a very harsh/abrupt part throttle 1-2 shift in my 06 Silverado with a 4l80e swap. Wot and heavy throttle/higher speed shifts are nice firm thumps, but part throttle around town, taking off from a stop, the 1-2 shift feels like it will snap a u joint. The truck is a reg cab short bed 5.3 1500. Weighs 4800ish pounds. 3.73:1 rear gear. Engine is a mild build: essentially an iron block L33 with a healthy cam, force fed by a 78mm t4 turbo. The trans was built to handle the power, and has a 3600ish single disk stall. I?m using the pcm of nc harness to run the trans on the 60e trans file. I?ve tried the stock 60e pressure table, stock 80e file pressure table, etc with no change. I?m scared to back the low torque area shift pressure down below stock values. No torque management in the tune as my OS does weird stuff with tm enabled due to the high stall converter. The truck is speed density tuned, no maf.

I will post the file later this evening or tomorrow morning, along with line pressure figures as measured by mechanical gauge. Just looking for brainstorming ideas or if anyone has ran into this before. The tune seems to be spot on everywhere, I just have this very abrupt part throttle 1-2. I should also mention, it mainly does it when shifting automatically. If I manually shift it, the shift is not so firm.

[SilverBullet6.0]

turbo silver truck.hpt

Here is the file

[Alvin]

Sometimes you can't undo a shift kit with tuning. Have you talked to the trans builder?

I don't know about 4l80's but if the accumulator has been blocked off.. there is just not much I can do to get a comfortable 1/2 shift. I don't like going less than stock on pressures either.


I would try putting just a touch of TM back into the 1/2 shift just to see if you can get it to calm down.

[SilverBullet6.0]

Alvin, thanks for weighing in! I hope you don?t see anything I?ve overlooked in the tune regarding the harness adapter! The 1/2 accumulator is still there and active. 2-3 and 3-4 were deleted. I built the trans myself using a ?kit? from a well known builder/supplier. I have not talked to him, as there were several issues with my order and we did not end on good terms.