Locking TC immediately after shift?

[LS1_Dragster]

4L80E with loose converter. Can you have the converter lock at the same MPH or 1 MPH above the shift points?

Example, the 2-3 shift at light throttle is 20MPH so can I have the converter lock at 20MPH too? Or 1 MPH higher?

Right now there is no RPM drop between any shift, it stays around 2500 RPM unless the converter is locked. Once locked it drops 800RPM and I can cut the throttle in half which drops the RPM's even lower.

What I'm thinking of doing is have it lock in 3rd right at the shift which should feel like a shift since the real shift cannot be felt and the same going into 4th.

Then I would have it unlock at the same speed or 1 MPH higher then the downshift MPH.

Does any of this make sense?

Lee

[joecar]

That should be ok... but try it and see.

[LS1_Dragster]

I cant try it until tomorrow so I'm just thinking out loud and seeing if it's been done before with good results.

[joecar]

For example...

If the 3rd gear TCC lock table is below the 2->3 shift table, then the PCM simply locks the TCC on entering 3rd gear...

If the 4th gear TCC unlock table is below the 4->3 shift table, then the PCM uses the 3nd gear TCC lock/unlock tables when entering 3rd gear...

You see my point...? The TCC tables are gear specific.

[LS1_Dragster]

For example...

If the 3rd gear TCC lock table is below the 2->3 shift table, then the PCM simply locks the TCC on entering 3rd gear...

If the 4th gear TCC unlock table is below the 4->3 shift table, then the PCM uses the 3nd gear TCC lock/unlock tables when entering 3rd gear...

You see my point...? The TCC tables are gear specific.

Take a look at my tables if you have time. Will this work? I basically want the converter to lock after the 2-3 and 3-4 shifts.

Lee

[joecar]

That will work... the TCC will lock as soon as the upshift happens (because the TCC mph conditions are already met, and gear is same as table name)...

your 3rd gear TCC lockup curve is 1 mph below the 2->3 PT shift curve...
the 3rd gear TCC lockup curve has no effect until 3rd gear is hit, and then the mph conditions are already met (and the PCM commands TCC lock up in 3rd).

same with your 4th gear TCC lockup curve and the 3->4 PT shift curve...
the 4th gear TCC locup curve has no effect until 4th gear is hit, and then the mph conditions are already met (and the PCM commands TCC lock up in 4th).

[LS1_Dragster]

Great, thanks for taking the time. We'll see if this tames the loose converter and make cruising a little more enjoyable.

[ScarabEpic22]

Let me know how it goes, this might make me reconsider getting a converter for my TBSS, I dont want to lose a lot of gas mileage with one and this might help keep it the same.

[LS1_Dragster]

OK, I got to play a little bit.

I set the converter to lock 1 MPH under the shift MPH in hopes that it would shift then immediately lock but what it does is shift then nearly 3 seconds later it will lock. During this time the TCCmode is "App" then goes to "lock". During the "App" mode the TCCDC% goes from 0 to 97% very quickly, I assume the pressure to the converter is near max psi when the command is given to lock.

So, how can I get it out of the "App" mode sooner? It take so long that it sometimes shifts into 4th before it locks in 3rd.

Lee

[joecar]

Hmmm... try some experiments, see what happens when you set TCC to lock 1 mph above the shift mph.

[Ritch]

Sounds like you may want D2801 set to yes

[LS1_Dragster]

Sounds like you may want D2801 set to yes

No, this only causes a harsh shift which I do not want. Right now it works OK I just need it to lock sooner in 3rd.

Lee