DIY TCM Ideas

[robertisaar]

did some more research...

the 7730 has 6 native PWM outputs
the 6T and 6L transmissions need 6 PWM signals:

pressure control solenoid
TCC PWM
and the 4 pressure control "shift solenoids"

so, while it's possible to do, it eats up any other items that could benefit from PWM control.......

though, i could impliment a slightly less simple(ha) PWM output scheme for the remaining 5 (easily used) outputs that get calculated and updated when the processor goes through it's 80Hz loop, for example... that would allow the discrete outputs to be used as PWM, if they were to be needed.



anyways, the 6T and 6L are pretty much not that difficult to control once you have the information necessary to know how it does it's job. why GM decided to use 4 extra pressure control solenoids instead of just 1 extra shift solenoid, i'll never know, but it is certainly doable.

controlling the 4T and 4L transmissions is total cake. the oddball of the group is the 5L transmission.... 3 shift solenoids, 1 pressure control.... also seems like it will be dead simple to control.



so, that's always good news. and since you can find 7730s pretty much anywhere..... that's always good. that covers the output side of things, in terms of inputs, i should be able to make a good trans control program using:
RPM
VSS
Input Speed (doesn't exist on 4L60/4T60)
TPS
Trans Temp (optional on 4T60)
engine coolant temp (optional, though recommended)
MAP / Baro (optional, though recommended)

that's the pulsed and analog inputs anyways. discrete switches aren't very demanding either, mostly just the shifter position stuff.

[robertisaar]

revisiting this since i have too much..... time on my hands, punching out a list of stuff that will be in the calibration. just working on tables ATM since those are the easiest to visualize what will be needed.

anybody have suggestions for other tables that might be needed?

so far:

1st-6th up and downshifts in normal, hot, cruise and alternate pattern (alternate can be used for whatever you want, economy, towing, performance, 2nd/3rd/4th gear start, etc)
target upshift speeds for normal, hot, cruise, alternate
the PCS/FMC line pressure rising and line pressure falling commanded current charts
base line pressure from 0-128 MPH (TPS vs MPH)
1st-6th gear line pressure offsets to previous table (vs trans temp)
TCC lock and unlock thresholds from 2nd-6th gears in normal, hot, cruise, alternate patterns
minimum and maximum TCC Duty Cycle for 2nd-6th gears (via "targeting" when applying or releasing)
TCC PWM apply and release rate 2-6th gears (using TPS as a base and MPH as a multiplier)
trans fluid temp TCC PWM apply and release rate multipliers



am i missing anything important? currently at 137 tables and 3,417 bytes from tables alone..... still need to deal with the 4L60/65 3-2 downshift solenoid and the Park to Drive/Reverse stuff, but i THINK those are all of the major ones.... i guess i'm missing "tolerable" slip vs whatever stuff as well...

not sure if downshifts can really be adapted directly.... i mean, with upshifts, you measure shift time by measuring the amount of time it takes for RPM to stop dropping after a shift is commanded... during a coastdown downshift, the torque converter will pretty much be far under it's stall point, so you won't see RPM jump. and during a throttle opening downshift, RPM will jump due to the downshift and likely keep rising because of the added throttle....

so i guess downshift adapts need to use the upshift adapt data... consider a 2-3 upshift.... the time it takes is basically determined by the 3rd clutches wear/surface and the pressure being exerted on them(right?)... so a 4-3 downshift would also depend on the 3rd clutch condition for adapts.... so basically, the gear that's being entered determines what adapt data should be used.



thoughts?

[TurboGTU]

Lots of work there. I guess only torque management but on the Turbo grand prix code that's controlled by the engine since the trans is brainless. SO i guess don't worry about it yet untill we break stuff.

[robertisaar]

torque management will have to be done entirely by the ECM.... the only thing the TCM could really do is bump up line pressure, but that would already happen when getting into the throttle.

i MAY assign a discrete output that is used when detected slip exceeds a threshold and have the ECM read it to know to back off the advance... of course, the ECM would have to be setup to do this, so it may be a nAst1 ECM/7730TCM only feature.

i've also looked into the oddball GM transmissions, the Aisin AF33(which there are AWD models) is kind of goofy, but seems to be within the control capability of a 7730. Allison 1000, odd but workable. Saturn MP6/7(LOLOLOL) is dead simple too. however, all of those don't really follow the rest of the group, so those(if i do decide to support them) would probably have a unique program. i don't see too many being utilized though.... maybe the AWD AF33 for somebody's frankenstein project, but the others probably wouldn't be that useful.

[DefEddie]

As a Ford tech I have been into the 6F50's with mechatronic assemblies in the valvebody.
They were unserviceable at that time. I replaced several of them due to different recall and tsb reasons.
They were finicky,when the edges came out I was reprogramming them left and right due to programming issues.
They must have went thru 2-3 revisions just dealing with the downshift strategy.
As I remember there were no replaceable parts in it,it was replaced as an assembly and it was imporant to know the serial number of the new unit or something.
Can't remember why but had to go thru a procedure to program it in that could cause issues.

The Aisin's we dealt with that were in the 500's and freestyles were completely nonserviceable units.
Not the valvebody,the entire transmission.
We could get a few random parts like axle seals,pump seal etc.. But any issues called for replacement and we did not even have manuals.

I would be interested in having one that could control a 6t75.

[daveycav90]

Im currently controlling a 4t65e-hd with a home built megasquirt GPIO Board. They are designed for rear drive tranny but as posted above all having similiar set up for controlling the tranny.

Just another option if you are looking for a push button/manual shift mode and still have the option to be fully auto

http://www.msgpio.com/manuals/mshift/index.html

http://www.diyautotune.com/catalog/gpio-board-c-77.html?osCsid=d8de0abccb68d65936be2a4f5c2c6785

These will have to be hand built so soldering experience is needed

Dave

[robertisaar]

neat idea for what is close to a plug and play TCM, even relatively cheap at ~$230 considering what the TCI and similar units cost, but i'm still definitely going the 7730 route.... those things are everywhere, shouldn't cost more than $40 from a junkyard(and ~$100 for a reman) and are capable enough to operate any GM 6 or less speed transmission currently or previously made.

"manual" mode(which could be used for almost anything), among other features, STUPID-easy to impliment, something that i've had anticipated for quite some time.

[robertisaar]

anybody think shift speed, MPH shift points or anything TCC related should have seperate parameters for when in cruise control?

the more i think about it, the less important i think it is....

[TurboGTU]

I can care less about cruise control in a "hotrod"

[robertisaar]

true, but this can and will be used in vehicles with something other than "max effort" in mind...

i think i'm going to chop all of the cruise specific stuff... while it would be nice to have and doesn't take up a lot of room, i don't see why the "normal" settings won't work well while in cruise. the trans hot and alternate patterns(which can be used for whatever(towing/economy shifts/"sport shift"/full manual shifts)) should cover everything. hell, the alternate pattern could be used for a cruise pattern, if somebody really wanted to go about it that way.

[robertisaar]

actually, here's my best compromise so far...

normal

trans hot (obviously, you adjust the temp to cause this to whatever you feel is necessary)

alternate (performance/eco/tow/cruise/etc) (this is controlled via an external switch to select, or in the case of cruise, by the cruise module itself)

full manual (also external switch to select, shifts follow the shifter every time). this mode will have support for "paddle" shifters(another external switch to select between following the shifter and keeping the shifter in the highest gear and only follow the paddle signals). TCC control in this mode... probably have software flag to allow you to switch between using an automatic TCC control with manual shift points or have yet another external switch to allow manual TCC control as well.



so, that's really 5 different shift patterns, that should cover pretty much everything.

[robertisaar]

up to 178 tables so far... 5,542 bytes used for tables alone. the beauty of this being a specialized application is that i still have a BUNCH of space left for algorithm... and for controlling various other functions that would benefit from computer control.



anyways, new question: braking line pressure.... is this a very significant thing to consider? it sure does seem to add a lot of pressure when it's active. in some early 4L60E stuff, i'm seeing up to 90PSI getting added due to braking (or engine braking, depending on who wrote the XDF), in some late 90s OBD2 stuff, i'm seeing up to 50PSI being added for the same reason, always called "braking pressure" though, not engine braking.

since they're referenced by MPH, it looks like it could be used to assist engine braking and to bump up line pressure when at lower MPHs with the brake applied(burnout). so i guess i answered my own question, unless anybody else has a different take on it?



here's the current set of tables(mostly organized)... comprehensive is looking to be an accurate term thus far.

[robertisaar]

LOTS of progress today.... i like progress.

anyways, the 6L80/90 and 6T70/75 use an identical setup for the shift solenoids(identical solenoid combos required to produce desired gears), but i can't verify the 6T30/40/45 and 6L45/50 stuff yet.

if anybody can find tables like this:

http://img.photobucket.com/albums/v25/Stingray5522/Vette/Transshiftstates.jpg

for those transmissions, that will be almost the last of the info needed to finish up those applications. well, except for the base calibration, that's going to either need a lot of guesswork or info grabbed from GM calibrations.

[robertisaar]

so, more theories from the mad scientists lab:

i had this crazy thought a while ago, but it seemed overly complex, so i didn't give it much merit, but the more i thought about it, the more sense it made...

so, one downfall of the 4T60E over the 4T65 is the pressure control solenoid... well, i may have a workaround for that....

imagine if you will.... a computer controlled vacuum pump connected to the vacuum modulator. it takes the PCS signal that would have been intended for a 4T65 and uses it to target a vacuum to control line pressure... you would be able to dial in target shift times, control line pressure to reduce clutch slip.... basically, act like a 4T65, the only real difference being that no 4T60E has an input shaft speed sensor, then again, no 4L60E did that i know of either. this basically would give you an adjustable vacuum modulator that is constantly automatically adjusting based on need.

it seems odd at first.... but i don't see any reason why it couldn't be done. obviously, as a failsafe, you would want a vacuum resivoir, possibly pair up the vacuum pump with the engine itself in case the vacuum pump fails..... maybe even a compressor to pump up line pressure, especially for boosted applications....

anyways, this would require an auxiliary controller to interpret the PCS signal and to decide when to apply more or less pressure to the modulator....



it's an odd thought, but i do odd things.

[brian89gp]

I had a microcontroller sitting on the shift and TCC wires inline, disengaged and it let the EMC pass through and engaged it controlled the shift solonoids manually (up/down/lock buttons). The programming was solid and simple but once I put it into the car environment the noisy 12v source and the surges from the solonoids would feed back and crash the microcontroller (even through opto isolators). Swapped to a Getrag 284 shortly afterwards so never bothered to fix it.

There is a market for this type of thing in the GM 6.5 diesel truck world and the 6bt/4bt swap. The 92-93 6.5 diesel was manual injection with the 4l80e, had a transmission only TCM in it. Extremely hard to find and people regularly pay $200+ for the things when either swapping their 6.5 diesel to manual injection or any of the 4bt or 6bt swaps. Probably also find a market in the general GM truck world with people wanting a 4l60e/4l80e and an older carb engine.

How are you interconnecting the TCM and ECM?