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Thread: TCC lock/unlock issues potentially solved.

  1. #1
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    TCC lock/unlock issues potentially solved.

    For the past year or so, and possibly longer than that since the conversion from carburetor to TBI, I've been fighting an issue with the TCC lockup.

    But I believe it goes a little deeper than that though and am at a point where more opinions on the matter would be appreciated.

    The current setup is as follows:

    1993 3.4l 60v6
    1988 1228062 2.8l ecm and associated components.
    1991 4.3l throttle body with 4.3l injectors with the correct factory bracket ensuring the geometry of the TV cable and throttle cable are as they should be. Both 2.8 and 4.3 throttle bodies use the same bracket.

    On a side note, I have tried using a 1227747 ecm, but had more difficult time in tuning that one, so I reverted back to the 1228062 with the 2.8l BIN file. I may later on go back to the 7747, but the there seem to be parameters in the BINS that seem to be specific to 60 degree cranks and 90 degree cranks.

    In any case, I believe that one of the issues I might fighting is the amount of movement of the throttle when comparing the 2.8 throttle body to the 4.3 throttle body. It would seem to me that if both TB's are opened so that the voltage from the TPS is equal, while both throttle shafts may be at the same angle, the amount of air flow will be different.

    Now for both to be moving the same amount of air at a particular speed/rpm, the throttles would be open to a different amount. The TPS value would be different between the two, but the associated parameters in the BIN files can be changed to compensate for that, but, the TV valve travel would not be the same even though nothing physically changed between the TV cable/throttle cable settings.

    Any opinions?

  2. #2
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    Yes, bigger throttle bodies often mean more toque with less throttle, which mean more torque into the transmission with less TV cable pull.

    What is your TCC lockup issue?

  3. #3
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    Trying to determine if the distance that the throttle valve in the transmission is correct with the larger bore throttle body.

    (note that the cable is adjusted properly per the manual and various sites that discuss the TV cable adjustment)

    In the last thread about the TCC lockup values, I got a better understanding of those values in the BIN file, but those values aren't question, it's the discussion of the TPS percentage values that got me thinking about the difference in throttle plate travel between the larger throttle body and the smaller throttle body with relation to the throttle valve in the transmission.

    So you are saying less cable pull but more torque, then maybe I should go back to the 2.8 throttle body to ensure the correct operation of the throttle valve in the transmission.
    Last edited by damanx; 04-25-2016 at 04:52 AM.

  4. #4
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    I'd say you need to adjust your TCC lockup values to match the torque output of your engine.

    That's why they're adjustable. The transmission is used in a LOT of vehicles and they're all different weights, different torque inputs, different throttle bodies. The TV cable is going to be adjusted differently on all of them, and the TCC lockup values are the fine-tuning to match the different applications.

  5. #5
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    Quote Originally Posted by Xnke View Post
    I'd say you need to adjust your TCC lockup values to match the torque output of your engine.

    That's why they're adjustable. The transmission is used in a LOT of vehicles and they're all different weights, different torque inputs, different throttle bodies. The TV cable is going to be adjusted differently on all of them, and the TCC lockup values are the fine-tuning to match the different applications.
    I understand that, but the question still remains as to whether the throttle valve in the transmission is moving the same amount between the two different sized bore throttle bodies.

    And here is the other thing, besides me wanting to set the truck on fire, is that this engine/tranny/tbi system is a Frankenstein.

    Should I be using the governor that was in the '85 transmission because it was in front of a 3.73 rear? Should it be the 1991 Camaro 3.1 governor since that is what the transmission came out of?

    There is such a hodge podge of parts on this truck running right now that I am actually amazed it runs sometimes.

    I'll upload the latest datalog later. One of the most annoying things is all the knocks I am seeing and every adjustment I've made so far that should be affecting them isn't. Hell, I'm not even sure if they are real knocks...
    Last edited by damanx; 04-25-2016 at 10:10 AM.

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    It will travel the same amount between idle and WOT. But at part throttle with a larger throttle body the engine typically will produce more torque with the same throttle which puts more torque into the transmission while the transmission has a lower line pressure. The transmission can be re-calibrated to compensate.

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    When you say "recalibrated", are you talking shift points via governor or in the valve body.

    I can't find a "shift point chart" for the 1985 700r4 that was in the truck, but according to the chart for the 91, it appears that my shift points are occurring about 3-4 mph too soon.

    At the moment, I don't recall what governor is in there, but I think it might the one from the 85 tranny which I do remember having heavier outer weights.

    If that is what is in there, I am going to put the 91 governor in and see if that makes a difference.

    Thoughts?

    (thinking back, I wish I had not changed so much at once)

  8. #8
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    So, what issue ae you having with TCC? Is it hunting between lock and unlock? Is it not locking up until higher speed or lower throttle opening or...?

    Bud
    If it don't fit force it, if it don't force fit f&%@ it!

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    TCC is working as it should be. I do need to work on the TPS% values a little more, but that's not the primary concern right at the moment.

    At the moment, I believe I need to start looking at the governor and my shift points.

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    I'm not a transmission expert but possibly the governor and the TV valve or whatever else is required to modify part throttle line pressure.

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    If you want later shifts without having to alter tv pressure, take the governor and grind some meat off the weights. the lighter the weight, the later the shift.

    Alternatively, you can buy a gov calibration kit and change weights and springs to fine tune the gov operation.

    Bud
    If it don't fit force it, if it don't force fit f&%@ it!

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    What transmission is this? Do you have the case number?
    lakedrifter

  13. #13
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    Quote Originally Posted by lakedrifter View Post
    What transmission is this? Do you have the case number?
    700r4 FBM model

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    Quote Originally Posted by buddrow View Post
    If you want later shifts without having to alter tv pressure, take the governor and grind some meat off the weights. the lighter the weight, the later the shift.

    Alternatively, you can buy a gov calibration kit and change weights and springs to fine tune the gov operation.

    Bud
    The outer weights on my governor are exactly like this one:

    Attachment 10490

    The inner weights on mine are heavier than those pictured, and I do have a governor with those triangle inner weights, but my understanding is that the inner weights and springs do not affect part throttle shifting.

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    I need the number on the case above the pan, see what model it is. Im know expert, but i do know that depending on model. They used different lock-up switches. Dessignated by color. Metalic and black, metalic and white, blue. All had a different psi for locking up in 4th. I cant tell you what the psi for each were because i cant find a list. But i might be able to tell you what you have.

    In 1993 700r4 got completly rod of the 4-3 downshift switch.
    lakedrifter

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