TCC Lockup During Shifts?

[DrX]

Comparing my truck tune to a Z06 tune I noticed that TCC Lockup during upshifts(D2801) is disabled in the truck tune but allowed in the Z06 tune(the TCC lockup speeds are sometimes less than the shift speeds in the Z06 tune).

I have altered my shift tables to yield downshifting that is more suited to engine load similar to the Z06 tune. But now I have TCC lockup speeds that are only slightly higher than the 2-3/3-4 upshift speeds. So I get a double kick in the seat with the upshift closed followed by TCC lockup. Not to mention the kick as the TCC applies and releases if traffic happens to be moving close to the TCC Apply speeds.

Would there be a problem with setting up a truck to have TCC Apply concurrent with an upshift? What about when towing? I have a built trans and PI multi-disk TC.

Should the TCC Pressure tables be modified for this TC?

[joecar]

It's ok for the TCC apply speeds to be lower than the upshift speeds... the TCC apply should occur immediately/concurrently on upshift;

the reason trucks/towing have TCC apply speed above the upshift speed is that they are heavier and can benefit from the torque multiplication (which occurs while TCC is not applied and TC is slipping due to engine torque being applied).

I don't know about pressure.

[jfpilla]

The stock C5 A4 table has NO selected. The Z06 has YES. Since the Z06 doesn't have a converter I guess it doesn't matter. Was a Z06 file used and not just some tables copied?

[DrX]

It's ok for the TCC apply speeds to be lower than the upshift speeds... the TCC apply should occur immediately/concurrently on upshift;

the reason trucks/towing have TCC apply speed above the upshift speed is that they are heavier and can benefit from the torque multiplication (which occurs while TCC is not applied and TC is slipping due to engine torque being applied).

I don't know about pressure.
Thankyou


The stock C5 A4 table has NO selected. The Z06 has YES. Since the Z06 doesn't have a converter I guess it doesn't matter. Was a Z06 file used and not just some tables copied?
Yes, I guess it would be hard to hurt the converter then.:) This was the Z06 tune that came packaged with the EFILive download. I haven't downloaded an C5 A4 tune to look at yet. I assumed that the tables in the Z06 tune applied to the A4.

I tried setting the TCC apply a little before the upshift VSS but it still seems to apply after the shift. Haven't tried changing D2801 to YES yet.

Also noticed that, while cruising in 3rd just over my Lockup VSS of 60 KMH, whenever the TP falls below 20% the TCC goes to OFF. Even though I have all TCC Release speeds for 3rd set at 50 KMH up to 31.25% TP. VSS was constant at around 65 KMH. So the TCC is constantly locking/unlocking while cruising at this speed.

One more question. I have lockup disabled for 2nd(all VSS set to 412 KMH) but i see that TCC enable is constantly switching on and off in 2nd. Is this normal?

[joecar]

Are you looking at the pid GM.TCCMODE to see if the TCC is being commanded locked...?

[DrX]

Are you looking at the pid GM.TCCMODE to see if the TCC is being commanded locked...?

Yes. In this screenshot the TCC is locking/unlocking.

http://i114.photobucket.com/albums/n241/TDOC2004/TCC1.jpg

A little further along in the log it stays locked even though there are blips where TPS falls below 20%.
http://i114.photobucket.com/albums/n241/TDOC2004/TCC2.jpg

Then later TP falls below 20% but TCC goes to Coast mode rather than releasing. What determines whether Coast mode or TCC Release is commanded?

http://i114.photobucket.com/albums/n241/TDOC2004/TCC3.jpg

[jfpilla]

Have you tried setting the misfire tables to 32000?

[DrX]

Have you tried setting the misfire tables to 32000?

No. Should I log some misfire PIDs to determine if the TCC release is related to a misfire situation(real or false).

[jfpilla]

I would just set C5621 to C5627 to 32000. If it corrects the unlocking you can go back and track the missfire.

[DrX]

I would just set C5621 to C5627 to 32000. If it corrects the unlocking you can go back and track the missfire.

OK, tried that. The TCC is still behaving the same. Did notice that it remained OFF until the TFT reached 75*C or so. Not sure if this is normal.

http://i114.photobucket.com/albums/n241/TDOC2004/TCC5.jpg

http://i114.photobucket.com/albums/n241/TDOC2004/TCC4.jpg

[jfpilla]

I think 72* or so is lockup temp.
The only other thing I can think of is that your lockup speeds are too close to your shift speeds. Either set them to yes and lower than shift speed or at least 10mph higher as a test.

[joecar]

Also, if you haven't already, make sure the TCC release MPH table is lower than the TCC apply MPH table for each gear.

[DrX]

I think 72* or so is lockup temp.
The only other thing I can think of is that your lockup speeds are too close to your shift speeds. Either set them to yes and lower than shift speed or at least 10mph higher as a test.

They were well above the shift speeds. Still see the same behaviour with it set to YES(guess it doesn't matter if the Lockup speeds are higher than the shift speeds). Looks like the TCC always goes to OFF when TP falls below 19% except at higher speeds where it goes to Coast mode. This is illustrated in the screenshot below.


Also, if you haven't already, make sure the TCC release MPH table is lower than the TCC apply MPH table for each gear.

All TCC Release speeds are below the Apply speeds.

http://i114.photobucket.com/albums/n241/TDOC2004/TCC6.jpg

[N0DIH]

Sorry for the old post on this, but the LT1 RPO V4P (HD Tow Package, not to exceed 7000#) and the Corvette both have this "UPSHIFT TURNS TCC OFF" turned OFF, all other models (B body and F Body) have this turned on. I find it makes smoother shifts with it unlocking during shifts.
The V4P car and Y Body both have fairly stout trans pressure tables, V4P really so. The F Body and B body are much tamer.


Comparing my truck tune to a Z06 tune I noticed that TCC Lockup during upshifts(D2801) is disabled in the truck tune but allowed in the Z06 tune(the TCC lockup speeds are sometimes less than the shift speeds in the Z06 tune).

I have altered my shift tables to yield downshifting that is more suited to engine load similar to the Z06 tune. But now I have TCC lockup speeds that are only slightly higher than the 2-3/3-4 upshift speeds. So I get a double kick in the seat with the upshift closed followed by TCC lockup. Not to mention the kick as the TCC applies and releases if traffic happens to be moving close to the TCC Apply speeds.

Would there be a problem with setting up a truck to have TCC Apply concurrent with an upshift? What about when towing? I have a built trans and PI multi-disk TC.

Should the TCC Pressure tables be modified for this TC?

[joecar]

Also, unlocking during an upshift allows the engine RPM to be kept up higher as the new gear grabs.

[N0DIH]

That is why I changed that setting on my LT1 tow package car, to get the higher rpm in the next gear until lockup. So it gives me a little more flat rpm (less drop at gear change).