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Last edited by billygraves; 06-30-2019 at 06:19 PM.
I set up a monitor to datalog TPS, trans temp, torque signal pressure and RPM and experimented with the following tables:
Pressure ramp delay time vs tps vs shift (sec)
Extended ramping pressure time vs tps vs shift (sec)
Initial ramping pressure vs tps vs shift (psi/sec)
Ramping pressure vs tps vs shift (psi/sec)
Post shift ramp time vs tps vs shift (sec)
Preliminary findings are summarized below. These are preliminary because I failed to save the datalog, and am going off memory what I observed. Note my son was driving the truck while I worked the laptop.
1) Ramping pressure (psi/sec) increases or decreases line pressure for the actual time (sec) taken to complete the shift.
2) Pressure ramp delay time (sec) delays the initiation of ramping pressure. For example, if delay time is set for 0.5 second, the shift will begin, and continue for 0.5 second until the onset of any ramping pressure change.
3) Initial ramping pressure (psi/sec) works in conjunction with the pressure ramp delay time. Some stock 4.3V6 tunes have 0.3 second delay time, positive initial ramping pressure and negative ramping pressure. Line pressure is increased at the initial ramping pressure rate for 0.3 seconds, and then reduced at the ramping pressure rate for the duration of the shift. (Note: It appeared in the data monitor that the initial ramping pressure took effect before any engine RPM reduction from the shift. However, I lost the datalog and will need to retest and verify this later.)
4) Extended ramping pressure time (sec) continues to increase or decrease pressure after the shift is completed at the ramping pressure rate. Pressure cannot exceed 90 psi (maximum in the BJYL tune) or fall below 0 psi.
5) Post shift ramp time (sec) was inconclusive. I'll need to do more testing. I assume this is the amount of time to return line pressure to "normal" after the shift is completed.
It also appears that the total time for shift pressure ramping can not exceed the line pressure modulation time in the 4L60E Line Pressure Parameters (1.2 seconds for all upshifts in the BJYL tune).
And the good news is trans temps stayed cool and I don't appear to have burnt any clutches.
Last edited by Roadknee; 03-24-2014 at 04:38 PM.
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Last edited by billygraves; 06-30-2019 at 06:19 PM.
Given a stock 4L60E calibration... what pressure or pressures would you adjust? For overall durability. Not for economy or for gentle shifts which GM called sales shifts, you know the big 1,2,3 sssslllluuuusssshhhh feel of a Caddilac. I like to feel a trans shift. But I do not like to feel it bang. I'm not asking for shift feel, I'm asking for overall safe improvements!Originally Posted by billygraves
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
On the otherhand I like how my 4L80E shifts with authority. Tends to break the tires loose anywhere over 1/2 throttle on the 1-2 shift.
Was there ever a reply to this question? I, too, would like some advice on safe pressures for safe, firm shifts.
Taking a quick look it appears the tables saying psi are wrong in this xdf like it is in other definitions. The 4L60e operates at 200psi plus so how can 90psi make sense for a maximum line pressure? With the max pressure scalar left set at 90psi, the code will take the main pressure table and then add any modifier table values before looking the answer up in the force motor table and applying that current to the line pressure. The "psi" adding the tables together is basically divided by the max pressure scalar so increasing the max pressure and increasing the tables would actually do nothing useful.
Last edited by lionelhutz; 08-28-2014 at 09:59 PM.
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Last edited by billygraves; 06-30-2019 at 06:20 PM.
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Last edited by billygraves; 06-30-2019 at 06:20 PM.
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