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I have been spending so much time learning how to tune the motor that I need to start thinking about tweaking the 4L60E. Most of my customers are 6 speeders but I have a few big inch motors to build that are going into automatic cars. What are some things to focus on without complicating things to get the tranny shifting solid. Is there a sticky or tutorial out there??
Howard
I haven't seen one, but i'm a M6 guy...
Might be a prime opportunity for you to write the tutorial
I have played with the upshift rpm and torque reduction. Busy working up the courage to fiddle with the shift times.
I am a bit loath to play to much as boxes are expensive to repair here and most of my customers have 6 speeders.
0. Turn off traction control switch.
1. Decrease shift times to 0.3s.
2. Increase base shift pressures by about 5%
(do not increase pressures by more than 15-20% total or pump wears out prematurely).
3. Reduce torque reduction by about 10%.
4. Increase max. allowed engine torque.
Test drive, and readjust 1, 2, 3 above;
You can adjust portions of the curves so you can tune the shift feel at any speed.
I find that torque reduction has a larger effect on shift feel, more than than base shift pressure; shift time has an effect down to about 0.1-0.2s.
When test driving, look for:
a. how quick the shift occurs.
b. how firm the shift is; you want firm without jerking.
c. part throttle downshifts should be very definite and quick;
may induce tire spin if torque reduction has been reduced alot.
d. full throttle down shifts should induce tire spin.
e. monitor trans PIDs like shift times and others.
If you change to stickier tires, then you may want to retune.
Pay attention that it does not jerk when shifting at any speed;
consistent jerking is hard on trans. and axle and engine.
Like engine tuning, it is time consuming, black box mode comes in handy.
How would you modify this formula for SC/Turbo'd? Any differences?
I haven't got a SC/turbo [...I don't have one, Yet... :)],
but it would be the same procedure, except in this case you may have to:
a. increase max. allowed engine torque by more,
b. reduce torque reduction by less (otherwise engine will hit trans. too hard on shift, unless you want it to (if you have a built trans. and built axle)).
If you make a lot of torque (...and you have big torque 8) ...), you may want to use torque reduction to control the amount of tire spin on each shift to try to not lose MPH.
Regardless of SC/turbo, if your trans. has a shift kit installed, then do not increase the base shift pressures without also monitoring the line pressure (using a pressure gauge connected to the test port on the side of the trans.) since the shift kit takes care of this (otherwise the line pressure will go too high and may cause damage); shift kit also increases flow volume to apply servos so that clutches/band apply faster and hold tighter (important if you have big torque).
Regardless of SC/turbo, the tuning process involves repeatedly tweaking shift times and torque reduction until you like the feel of each shift;
a good shift is firm, quick and you don't lose much time or MPH.
Note: may shift a little firmer when cold, so allow warm up before tuning.
After you're happy with the shift feel, then tune the MPH and RPM shift curves to suit your engine to get best ET/MPH.
If the shift feel is firm and quick (without jerking), then the slipping that occurs during clutch/band transition is reduced to a minimum, and this protects friction material from wearing prematurely and reduces the amount of heat produced (although this may be swamped by the heat produced by the toqrue converter).
Torque converter multiplies torque proportional to slip (somewhat proportional), so disable TCC apply during shift.
It may be ok to let TCC apply during shift for street, but not for strip.
TCC releases at WOT to protect TCC friction plate.
Trans. fluid cooler is good, and is required with stall TC, must keep "average" temp below 95°C to protect seals.
Synth. ATF is good (resists heat), but there's big debates about synth. ATF; I like it and use it in my daily driver.
Cheers
Joe
Joe,
When you say to increase the base shift pressure, are you implying the following paramters; D0701, D0702 and D0703?
How does the desired shift time work? When does the time start ,that is controlled by parameters D1108, D1109 and D1110?
Appreciate the information but I just want to know what I am changing and not just to make the change!
Anything with the forced motor current function?
Thanks
Howard
Howard,
The desired shift times are exactly that, the PCM wants (or expects) the shift to complete within 'x' time, if it does not it alters the pressures to compensate.
I remember back around 2000BE (2000 Before Edit) when people would fit shift kits that would work great for a few weeks then usually damage the trans because the PCM was still trying to achieve a nice soft sloppy factory shift and the pressure would just fall out the floor trying to slow the shift down.
If you bump the line pressures up in the tables you should also reduce the desired shift times as well, even drop them by say 0.2sec
From memory if you set them to 0.00 it disables the trans learns.
Also, remember you can see the learnt pressure adapts in the scantool under the LS1/LS6 menu. But, some cars have learning, others don't.
Cheers,
Ross
If you set the shift times too low, say .1 you could damage the trans also, The transmission can only shift so fast physically, due to hard parts in the valve body, So if you command a shift faster than it can go, the pcm will max out its adaptive shift learning on it and raise pressure way to much for no reason. If you go less than .2 it is better to just put 0 in that table and turn of the adaptive learning.
With a shiftkit, you are required to turn off all tranmission adaptive learning and 0 out that table set. Then you are required to pull the tm also. So it dont burn up the clutches prematurely.
I have a shift kit and vette servo, so should I set all my shift times to 0 and then adjust the shifts for my liking with the shift pressures? I've never liked the part throttle shift from 1-2, it was always too hard. I've softened it by increasing shift times, but still a little too firm around town. All the WOT shifts feel good, BTW.Quote:
Originally Posted by wait4me
Howard,
Yes, those ones.Quote:
When you say to increase the base shift pressure, are you implying the following paramters; D0701, D0702 and D0703?
The PCM initiates the shift and monitors the time taken for the engine rpm to drop the correct amount for the gear ratio;Quote:
How does the desired shift time work? When does the time start, that is controlled by parameters D1108, D1109 and D1110?
the PCM compares the time taken with the desired shift time and adjusts ("adapts", "learns") the line pressure for the next time this same shift occurs.
If you reduce shift time and the log consistently shows otherwise, then don't reduce it any further (increase it until log concurs).
As Ross said, some cars have learning, some don't.
Make small changes, log data and display as both charts and maps to get a better picture of what happensQuote:
Appreciate the information but I just want to know what I am changing and not just to make the change!
(e.g. be creative with maps: shift time (vss vs tps), shift error (vss vs tps), etc...).
D3801 this table represents the physical capability of the pressure control solenoid (PCS, a.k.a. torque force motor, TFM);Quote:
Anything with the forced motor current function?
GM filled in this table by measuring the pressure regulated by the PCS (after first calibrating the PCS);
it's best to leave this table alone
(unless you modify the PCS by turning the calibration screw [bad idea];
it's possible to tweak this table if you use a pressure gauge and you're able to keep the trans.
at a constant temp while you measure the range of pressures produced by the current range (Scan Tool BiDir mode);
Note: as current goes down, pressure goes up).
In table D0801, increase the torque reduction for the lower values of delivered engine torque and see if this softens the around town PT 1-2 shift.Quote:
Originally Posted by kbracing96