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Discussion Starter · #1 ·
OK then, I will place this as a technical question rather than a "does anyone know where I can get" question...

Can anyone explain the operational mechanism that creates a downshift in the automatic transmission. Is it purely mechanical or does it require firmware control from the ECU?

What we all know is:

- Auto downshifts occur during heavy acceleration while in the e-shift mode or auto mode.

- Requested downshifts work in the e-shift more.

- You can ask for an upshift in e-shift mode, but it might not give it to you if you are heavy on the gas and not fully through the rev range yet.

I would really be impressed if someone can answer this question in detail. The guys at my dealership could not even come close.

Thanks in advance for you efforts.

Steve
Ottawa Canada
 

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It's pretty SIMPLE really.
The computer is smarter than any of us!!! :p
The computer takes inputs from different sensors and it knows the throttle position, and RPM. Then it decides when to shift. For the most part it has been very good to me. I have had mine for about 4 months now. The shift gate really will only limit the highest gear available for the computer to shift into, whether your are in the gate or useing the buttons. I do find that the gate is a little quicker to respond though!!!

Good luck
Kevin
 

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the ecu monitors parameters, eg: rpm, tps, speed ... and it sends an electrical signal to the transmission telling the solenoids to open and close, and it controls line pressure, and fluid "routing" for lack of a better word. the hydraulic fluid is what makes the auto trans work.
your question isn't too clear, maybe that will answer it

-gte




issteve said:
OK then, I will place this as a technical question rather than a "does anyone know where I can get" question...

Can anyone explain the operational mechanism that creates a downshift in the automatic transmission. Is it purely mechanical or does it require firmware control from the ECU?

What we all know is:

- Auto downshifts occur during heavy acceleration while in the e-shift mode or auto mode.

- Requested downshifts work in the e-shift more.

- You can ask for an upshift in e-shift mode, but it might not give it to you if you are heavy on the gas and not fully through the rev range yet.

I would really be impressed if someone can answer this question in detail. The guys at my dealership could not even come close.

Thanks in advance for you efforts.

Steve
Ottawa Canada
 

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Mr. Negative
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G- he waited 7 days and 4hrs. :lol: that's pretty patient.

IS300GTE said:
... as for you waiting a whopping 4 hours and 17 minutes for a response, f*ck off

-gte
 

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whoops, that day thing slipped by me :oops:

sorry about that steve, i appologize


IS_Dude said:
G- he waited 7 days and 4hrs. :lol: that's pretty patient.

IS300GTE said:
... as for you waiting a whopping 4 hours and 17 minutes for a response, f*ck off

-gte
 

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Discussion Starter · #8 ·
Thanks IS300GTE, we are getting somewhere.

According to your answer, shifting decisions are made purely by the ecu and/or e-shift commands, there is no mechanical mechanism that forces a downshift during hard accelaration.

If this is true, then it is possible to create a new firmware download that would stop the darned transmission from downshifting in e-shift mode. Do you know of any deveopment team out there that can tackle, or has tackled, this?

Steve
 

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besides lexus corporate, no

i have been told that if you unplug the trans electrical connector, it defaults to 3rd gear, if you are trying to dyno

i'll recheck the manual, as auto trans' are not of much interest to me (and therefore i'm not fresh on their info) but i don't think there is any mechanical assist, like some of the other tran's that took a vacuum signal or whatever



issteve said:
Thanks IS300GTE, we are getting somewhere.

According to your answer, shifting decisions are made purely by the ecu and/or e-shift commands, there is no mechanical mechanism that forces a downshift during hard accelaration.

If this is true, then it is possible to create a new firmware download that would stop the darned transmission from downshifting in e-shift mode. Do you know of any deveopment team out there that can tackle, or has tackled, this?

Steve
 

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.net superior m.f.
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issteve said:
OK then, I will place this as a technical question rather than a "does anyone know where I can get" question...

Can anyone explain the operational mechanism that creates a downshift in the automatic transmission. Is it purely mechanical or does it require firmware control from the ECU?

What we all know is:

- Auto downshifts occur during heavy acceleration while in the e-shift mode or auto mode.

- Requested downshifts work in the e-shift more.

- You can ask for an upshift in e-shift mode, but it might not give it to you if you are heavy on the gas and not fully through the rev range yet.

I would really be impressed if someone can answer this question in detail. The guys at my dealership could not even come close.

Thanks in advance for you efforts.

Steve
Ottawa Canada
these guys have that thing all figured out :

http://www.transmissioncontroller.com
 

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Discussion Starter · #11 ·
Thanks malofquist

Thanks for the link, that is exactly what I would be interested in. Unfortunately the company looks like it is on a bit of a shoestring. I'll let you guys know if anything comes of my requests for info.
 

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Re: Thanks malofquist

issteve said:
Thanks for the link, that is exactly what I would be interested in. Unfortunately the company looks like it is on a bit of a shoestring. I'll let you guys know if anything comes of my requests for info.
I called them and they told me to download the lastest software to get an idea of what the tranny controller will control check this out:

http://www.transmissioncontroller.com/download/tcu/TCU-CD.exe

file ---> open ---> calibration file then expand folder calibration/tuning -->calibration A....

notice how load vs accumlator pressure and line pressure is adjustable on the fly.

looks like every possible parameter is adjustable -- I can't wait to get one, I'll be tuning my transmission!

press control-M this is what my I want my dash to look like! I'm takin' out the instrument cluster and putting in an LCD with this 'monitor' screendisplayed :p
 

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thats the exact same thing I wanted to know. I hated even though you choose what gear your currently in it still downshifts if you go WOT. It suks it totally defeats the purpose of it being in the m-mode. O by the way the pcs website looks like it offers us e-shifters a nice product.
 

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MyExLex said:
thats the exact same thing I wanted to know. I hated even though you choose what gear your currently in it still downshifts if you go WOT. It suks it totally defeats the purpose of it being in the m-mode. O by the way the pcs website looks like it offers us e-shifters a nice product.
we should start a new thread to see if anyone has experience with transmission controllers.
 

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malofquist said:
MyExLex said:
thats the exact same thing I wanted to know. I hated even though you choose what gear your currently in it still downshifts if you go WOT. It suks it totally defeats the purpose of it being in the m-mode. O by the way the pcs website looks like it offers us e-shifters a nice product.
we should start a new thread to see if anyone has experience with transmission controllers.
I don't know much about the OEM transmission controllers...but I am scratch building (programmable electronics, display, datalogging and shifting system) a pnumatic semi and full sequential system for my Solo 2 prepped Toyota Starlet. It's taken quite a long time to perfect and design, it will be going through testing this up and coming Solo 2 season.
 

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Discussion Starter · #16 ·
Hey guys, here is the full question and response to my questions posed to Powertrain Control Solutions:

________________________________________

To Power Control Solutions:

I am interested in your transmission controller for my Lexus IS300. I have a few questions:

My car has the “e-shift” system, which in my opinion is doing well accept for one particular functionality, the transmission downshifts by itself when hard on the gas in manual mode.

Will your product allow me to disable this “feature” without affecting the rest of the settings?

Do you have specific harnesses available for my car at this time?

Thanks in advance for your help.
______________________________________________

Response from the good guys at Power Control Solutions:

Yes our unit will allow you to modify this behavior in manual mode. Yes we have developed a harness for the A650E (the transmission in the Lexus IS300) though at this time the connectors are not readily available from the manufacturer. This requires you to either cut and send us your sub-harness and perform some wiring work or to source the harness from a junkyard or other location.

Something to keep in mind when working with a stock or relatively unmodified vehicle is that your check engine light will come on when installing our transmission controller. Also, your dash gear indicator will no longer indicate gear position when in manual mode. Lastly, our transmission controller is fully programmable and does not necessarily mimic the behavior of the stock settings though you are able to program the controller to behave like the stock controller if you wish. An added feature with manual shifting on the IS300 is that our unit will allow first gear selection when in manual mode which the e-shift does not allow.

Feel free to ask should you have any additional questions,

James Ballenger
Powertrain Control Solutions
[email protected]
Phone: (703) 815-2962
Fax: (703) 995-4894
www.powertraincontrolsolutions.com
 

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WOW! That's impressive.

So the only negative I see is that I'll lose the indicator for what gear it's in. If I had that I'd be 100% happy. The other issues are academic for f/i guys.

Very good news. Thanks issteve.
 

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IS_Dude said:
WOW! That's impressive.

So the only negative I see is that I'll lose the indicator for what gear it's in. If I had that I'd be 100% happy. The other issues are academic for f/i guys.

Very good news. Thanks issteve.
Those PCS guys also sell a digital display that will display what gear you're in (it can be programmed to display ANYTHING about the car actually. I have the Tech3 and this dash display would be like having a laptop with me at all times -- I can monitor everything that the Tech3 is hooked into.

http://www.transmissioncontroller.com/products/display.html
 

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malofquist said:
IS_Dude said:
WOW! That's impressive.

So the only negative I see is that I'll lose the indicator for what gear it's in. If I had that I'd be 100% happy. The other issues are academic for f/i guys.

Very good news. Thanks issteve.
Those PCS guys also sell a digital display that will display what gear you're in (it can be programmed to display ANYTHING about the car actually. I have the Tech3 and this dash display would be like having a laptop with me at all times -- I can monitor everything that the Tech3 is hooked into.

http://www.transmissioncontroller.com/products/display.html
that is sweet..

but what about Haltech???? :cry:
 
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