Performance parameters for shift and TCC for 94 4l60e(stay in 3rd gear like a manual)

[knute_gis]

I have been playing around with the shift points in my 94 Formula.
It definitely makes the car more enjoyable to drive!

My first goal was to have it not shift into 4th until reaching 100mph for back road driving.
-I accomplished that with these shift settings.
shift points.jpg

My second goal is to have it stay in third gear with 0.0 throttle.
-I thought the below TCC settings would do that but when I lift off the gas it still acts like it goes into neutral.
-I don't know much about automatic transmissions but I'm guessing the torque converter is releasing.
-Below are the current settings I have. When I manually shift it into the third it does what I want but was hoping it can be done with tune settings.
TCC perform settings.jpg

I don't know if this is possible but really appreciate any help you guys can give!
Thanks, Knute

[NomakeWan]

I've just started messing with these myself, actually! What timely content. Anyway, if I'm reading your maps correctly, your Torque Converter Clutch settings are set to never lock up at all until the TPS reads 93.8% in 3rd gear. Then it will lock once VSS reads 95 MPH, and unlock once VSS reads 90 MPH. You probably want to invert your values to get what you're looking for.

Also, you should check the three flags under TCC and make sure they are not enabled if you're trying to keep the torque converter locked at 0 TPS and slaved to only the TCC tables.

[tayto]

I believe most 4L60Es will not engine brake in D (3rd gear). There is a shift kit for this IIRC. Your trans will run hotter by not locking up, its life will be shortend. There is always the option to run non-lockup converter.

[knute_gis]

So I’m a little confused on terminology.
I think this is correct...
Release = Not locked up
Engage = Engine brake = Locked up = stay in gear

Sometimes it’s hard to figure out if the mph setting is for
above that speed or below when the ecu reacts.

I also thought it was weird that the 93.8 & 100 are set at lower mph
but that was the factory settings and thought I would mess
something up.

Thanks for your guys help

[NomakeWan]

It's always "at" that speed. That's why there's a 5MPH "buffer" zone between the release and engage values. It won't lock until VSS is at least 95 MPH. Once locked, it won't release until VSS is at most 90 MPH.

As long as you keep this sort of buffer zone in mind you should be fine, though I do worry about longevity issues. I don't think these torque converters were meant to be used as clutches.

Best of luck!

[knute_gis]

I’ll try a few more things and see if it makes a difference. I’m probably trying to do something that is only mechanically controlled.

Are any of you familiar with how the Chevy truck tow haul button works.

Wouldn’t it basically be the same thing I’m trying to do?

But maybe that wasn’t a thing until the 411 ecu came out.

[lionelhutz]

There is a 1-way sprag that prevents engine braking when the shifter is in OD or 4th position. Pull it back to the 3rd position and then there is small clutch pack in parallel with the sprag that locks and allow engine braking.


The description of the TCC lock and unlock MPH parameters is likely wrong. It always seems to be. At any fixed %TPS the TCC would lock when the speed goes above the lock setpoint and unlock when the speed goes below the unlock setpoint. It remains in it's current state between the 2 setpoints so it could either be locked or unlocked.

Also, the TCC setpoints have nothing to do (at least not directly) with what gear it is in. Indirectly, it locking or unlocking could cause you to move the throttle which changes the %TPS which then might cause a shift too.

[NomakeWan]

I’ll try a few more things and see if it makes a difference. I’m probably trying to do something that is only mechanically controlled.

Not on this transmission. On the earlier one that had an ECM, sure. That being said...

There is a 1-way sprag that prevents engine braking when the shifter is in OD or 4th position. Pull it back to the 3rd position and then there is small clutch pack in parallel with the sprag that locks and allow engine braking.

Didn't know that! That's neat information, thank you.

The description of the TCC lock and unlock is wrong. At any fixed %TPS the TCC would lock when the speed goes above the lock setpoint and unlock when the speed goes below the unlock setpoint. It remains in it's current state between the 2 setpoints so it could either be locked or unlocked.

That sounds exactly like what the map in the computer shows, actually. The left column is fixed TPS in percentage-of-WOT, the top column is gear, and the cell value is speed. If release is at 90 MPH and engage is at 95 MPH and you accelerate from 80 MPH, then it won't engage until 95. If you decelerate from 100, it won't disengage until 90 MPH. Doesn't sound like there are any discrepancies at all. :)

[knute_gis]

Thank all of you for the great info.

I definitely have a better understanding!

I think there is a table for manual mode shift points. I can probably use my values from the above pic there.
Then use my perform button more towards drag racing.

I have really enjoyed learning the tuning process and the trial and error!