Re: Shift Adaptation Time
Quote:
Originally Posted by jimmyblue
My Predator purports to adjust shift times by a max
of -25%. But when I look at stock time tables the
delays run up to 0.3 (are these seconds?) and the
Predator tune read back as all 0.0 (with -20% - -25%
time adjusts). Which is a lot more than -25% down.
It just is an odd discrepancy of basis & value, no idea
about what the true param basis is.
LS1-Edit manual warns vaguely against zeroing the
shift time params because it "may accelerate wear".
But I have seen no indication of wear or malfunction
from the Predator settings in about a year or more of
driving around that way.
Shift time is transmission "learning".
Those tables are the maximum allowed time (in seconds) it takes to complete a shift.
If the value on the table is .3, that is 300 milliseconds.
If the time it took to make that shift went over that time limit,
the VCM will increase the trans line pressure for that shift the next time around.
If you increase your base shift pressure tables to firm up your shifts and the shift time is always under those limits, those tables are not used.
GM has those tables zeroed out on some models. That just means that the adaptive learing will not be used for that shift. There is not much need to set those values unless you are trying to get consistent shift times for around town driving.
You should always use the base shift pressure tables to set your transmission shift firmness.
A word of caution here. A competitor tells you to use the
Force Motor Current tables to set your shift firmness.
That table is used for the trans line pressure solenoid calibration. Making changes in that table will throw that calibration off. You should NEVER make changes to that table except under certain circumstances.
They have it labeled as Vs TPS Vs Temp. It is not. It is Vs the Commanded line pressure Vs Temp.
The commanded line pressure comes from the base shift tables and any transmission learning .
There are some load based tables that use %TPS to offset the commanded line pressure, but the Force Motor current table is not one of them. We will add those load based tables later on for those who wish to "fine tune" their shifting.
We provide that table for you for one reason. GM has a safety limit on the maximum line pressure allowed on certain models. The 100% column on some is set to
1.245 Amps which will shut off the trans pressure to keep from blowing seals and crushing the clutches.
If you have a custom built trans that can handle the full pressure (check with you trans Mfgr) then you can set that limit where you need to. We highly recommend letting a trans shop using a line pressure gauge to set and verify that maximum limit.
Happy tuning,
Ken
Re: Shift Adaptation Time
OK. I have them zeroed after driving with the original
stock tune for a couple of days, and the shift cycle time
is properly short. I wonder if there would be any
practical advantage in setting them to a nonzero, small
value like 0.05, just to make the trans not -have- to use max pressure? Do you know what the smallest "tick" in
this setting turns out to be? I guess maybe I could dope
it out from the increments shown in the stock table.
Re: Shift Adaptation Time
anyone give me an idea on settings for the base shift pressures to firm up my tranny shifts?
Re: Shift Adaptation Time
Quote:
Originally Posted by jimmyblue
OK. I have them zeroed after driving with the original
stock tune for a couple of days, and the shift cycle time
is properly short. I wonder if there would be any
practical advantage in setting them to a nonzero, small
value like 0.05, just to make the trans not -have- to use max pressure? Do you know what the smallest "tick" in
this setting turns out to be? I guess maybe I could dope
it out from the increments shown in the stock table.
0.00625
