Any idea why my 4L80E, with higher boost (above 10#), won't shift 1>2 or 2>3 as commanded? It definitely revs up quick (6.0 with 70mm turbo), but always shifted great, and as commanded, with a 200 or 250 shot, but now, with turbo, it doesn't. It NEVER seemed to want to shift by RPM. WOT Changes would only work, IF, I used MPH as the set point. That's been like that for 2 years. Today, had to set MPH like 5 mph less than it would actually shift at...no slippage, just wont shift, unless I let off throttle. Unfortunately, I left laptop in car, so cant attach log or tune right now.
It's a 2000 TransAm, 6.0, turbo, with a 2 year old Jake's D1 trans and Jake's triple disc converter FWIW

 

Probably just needs more lead time or line pressure or both.

 

Yes, I believe that is right. I redid all of my shift parameters using the Bluecat software today and honestly had no idea what the lead time function did.

Setting it at 5.00 was a little too much. Reset to 4.00 and it blew the serpentine belt off before I got test it out again

 

i used to have to set the shift rpm lower than what i wanted. as i added more power, id have to lower the shift rpm to keep the same actual shift rpm. its a little weird and frustrating but it seems thats just how they are.

 

What is/was most baffling to me, is that the transmission shifted at it's commanded MPH, every time, with a 200-250 shot of nitrous. Pretty sure torque was up there, on a 250 shot as well, ya know?

Anyway, I watched a half hour video yesterday, by Cesar Enriquez for trans tuning 6L80e's...He does a lot of high horsepower LS tuning, from what I could see.

Now I KNOW I do not have a 6L80e, lol, but the basics are explained in terms anyone can understand, and he also explains the LEAD TIME function on the BlueCat transmission tuning "app". He was tuning a 700rwhp car, and set lead time to 6.50, so I figured I'd start high (but not that high), at 5.00, which immediately got my shift point on the 1>2 shift, down from 6800, to 5900. I'm aiming for a tad higher, so as soon as rain stops, I'll test the 4.00 lead time setting and go from there...wish me luck.

I'm almost 2nd guessing myself, as 5900, is a LOT closer to 6100 than it was...and that was on wastegate (6#'s). Second guessing because at 14# of boost, that LEAD TIME setting may be perfect...

 

I ended up zeroing the mph and just using the rpm tables on my old rig that used HP Tuners

are you logging line pressures? It might be hanging if the EPC isnt dialed in right.

 

For whatever reason, this car, with it's 4L80e has always been MPH predominant...well, WAS...until the new turbo came in and slapped it around a little, lol.

My old 2000 Camaro, w/4L60e was always much more RPM predominant

My first "test" with the "NEW" BlueCat/Cesar transmission settings, it actually shifted too soon. I decreased the "Lead Time", but it's been raining every day since, so haven't been able to re-test.

I haven't logged line pressures or anything transmission related, except "Current Gear", mainly because with new settings, it actually shifted.

Not familiar with the term, "EPC"? What is that?

 

electronic pressure control. its pulsed by the computer to adjust line pressure to help with smooth shifts.

you can put a 0-300 psi chinese pressure sensor from ebay and plumb it into the port on the driver side of the trans , just behind the range sensor. log in HP tuners and it'll give you much better insight into what the trans is actually getting as commands go