Need information on PWM Trans tuning..
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From: Sierra Vista, AZ
Need information on PWM Trans tuning.. I recently installed a higher stall, 3800, TC and have adjusted the Apply/Release speeds to about where I feel good with them, and I kept LU in 3rd. I noticed at the threshold area after locking, if I cruise, the TCC will cause a "shutter" of sorts. I was told that adjusting the PWM can help smooth this out, or something. But I dont like playing with parameters unless I am familiar with the cause and effect.
The only tuning with trans I have done, is !Tor.Mgt, shift rpm, and now A/R TCC speed settings.
Seems to be confusing data on line pressure, and shift time.
Thanks,
Charlie
The only tuning with trans I have done, is !Tor.Mgt, shift rpm, and now A/R TCC speed settings.
Seems to be confusing data on line pressure, and shift time.
Thanks,
Charlie
Two aspects to this. One is, a hard straight apply will
take out some or most of the groaning from the
"feathered apply" that's done under light throttle. You
change the offset table to all 98% and it'll never go
lower than that, except 0% (by way of the main enable
valve thingy).
Other is, the force motor pressure may need jacked up to
make even 98% (~ full regulated line applied to the TCC)
adequate for light grades. It wasn't on my TCI SF3000.
Furthermore you may have to adjust it several times, I
suspect there is some "slip learning" deal that goes on
and it will fight you, seem OK one day and go back to
wimpy the next.
On the HPTuners site there is a sticky thread in the V8
Trans section about actual line pressure vs force motor
settings, but you probably need to deviate from the
stock ones and run more pressure, lower force motor
values, at the lower line-% indices. I expect that if you
log the slip-related things (RPM, engine load, force motor
current & %, TCC slip, etc.) you will see that the problem
lies in commanded line% being zero at cruise. 100% of
zero being not much help to the TCC.
Running excess force motor pressure is possibly bad though
I haven't seen damage yet, I only reprofiled mine to bring
it up early and come in quicker with load.
The force motor table also has a temperature axis and I
think this dimension is whacked, seems to aggravate slip
as things get hotter. I flattened mine out. It would be
swell to know what the proper profile in that dimension
would be, to keep a constant working head at the business
end of things across temperature. But I don't have the
line gauges for that little experiment.
take out some or most of the groaning from the
"feathered apply" that's done under light throttle. You
change the offset table to all 98% and it'll never go
lower than that, except 0% (by way of the main enable
valve thingy).
Other is, the force motor pressure may need jacked up to
make even 98% (~ full regulated line applied to the TCC)
adequate for light grades. It wasn't on my TCI SF3000.
Furthermore you may have to adjust it several times, I
suspect there is some "slip learning" deal that goes on
and it will fight you, seem OK one day and go back to
wimpy the next.
On the HPTuners site there is a sticky thread in the V8
Trans section about actual line pressure vs force motor
settings, but you probably need to deviate from the
stock ones and run more pressure, lower force motor
values, at the lower line-% indices. I expect that if you
log the slip-related things (RPM, engine load, force motor
current & %, TCC slip, etc.) you will see that the problem
lies in commanded line% being zero at cruise. 100% of
zero being not much help to the TCC.
Running excess force motor pressure is possibly bad though
I haven't seen damage yet, I only reprofiled mine to bring
it up early and come in quicker with load.
The force motor table also has a temperature axis and I
think this dimension is whacked, seems to aggravate slip
as things get hotter. I flattened mine out. It would be
swell to know what the proper profile in that dimension
would be, to keep a constant working head at the business
end of things across temperature. But I don't have the
line gauges for that little experiment.
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From: Sierra Vista, AZ
Jimmy, thanks, it'll take me a few times reading over all that to digest it all, but looks like less PWM and more line pressure basically? I can log and guess I need to huh. I dont have any issues (that I know of) during part throttle accel or WOT, only during constant cruise at the threshold mph. I ended up setting the A&R speeds based off what the TC was doing prior to tuning and it seemed fine after 50mph or so, so set 4th A @ 50mph and R @ 45. If I am coasting/cruising at say 53 I feel a little shutter, and 47 its down right nasty like the damn trans and stuff is about to fall out. Might it be better to adjust something else? Or would you think its still a matter of pressure vs. PWM? Hopefully its a loggable (new HPT Word 
) parameter that can help determine it as you mentioned.
Charlie
) parameter that can help determine it as you mentioned.Charlie
I have't seen violent shuddering off mine, just bad
sounding groans, hooting, squealing. May be a matter
of degree or of ATF brand. But the other, more "heavy"
shudder, might be misfire driven lock/unlock cycling.
I would expect this to be giving you SES light blinking
but maybe it's just a bit short of code-setting. You
should be able to log the TCC lock/unlock state as
well as TCC PWM duty and force motor current / %
and line%, and see whether there's commanded
unlock, or just bad chatter. A look at current misfires
would be a good idea as well, see if they peak when
things get ugly (or vice versa).
sounding groans, hooting, squealing. May be a matter
of degree or of ATF brand. But the other, more "heavy"
shudder, might be misfire driven lock/unlock cycling.
I would expect this to be giving you SES light blinking
but maybe it's just a bit short of code-setting. You
should be able to log the TCC lock/unlock state as
well as TCC PWM duty and force motor current / %
and line%, and see whether there's commanded
unlock, or just bad chatter. A look at current misfires
would be a good idea as well, see if they peak when
things get ugly (or vice versa).
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From: Sierra Vista, AZ
I have logged before, didnt save it, but there was no issue with misfire. It only happens right at the threashold mph, which is what I asked a couple ppl about, and was told to tune using the PWM. I guess raise the line pressure, and see whats up. If I am at the threshold mph and then tap the brake, it unlocks the TCC, thus stopping the jerking/shutter. If I speed up gently it will keep the 4th Apply TCC locked, and once I am around 55 or 60 (agains Apply is 50, Release is 45) then there is no issue with cruise mph at all, it just stays locked and boogies out, unless I go WOT and then it will unlock like it should.
