TCC lock/unlock issues potentially solved.

[damanx]

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?

[lionelhutz]

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?

[damanx]

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.

[Xnke]

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.

[damanx]

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...

[lionelhutz]

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.