3rd Gear TCC locking/unlocking issue

[1BadAction]

I have my trans tune very close to where I want it, holds 3rd with TCC locked up to 47mph then shifts to OD/Locked. The issue comes in at 3rd gear in traffic when I let off the gas, the TCC unlocks, then locks back up again when I put my foot back on the gas. PWM has been hydraulically eliminated and the TC is a 3200 Circle D, so it gets annoying, not to mention the excess wear this causes. I want it to stay locked when I am at 0% throttle and the TCC lockup tables reflect this, am I missing something else that causes it to unlock? Vehicle is a 2003 4.8L GMC Sierra.

[1BadAction]

Tune, if anyone wants to take a look.

GMC 4.8L_8-12-12.ctz

[joecar]

If the tune file originated from a truck then it will do that...


the car tunes kept the TCC locked on zero throttle (F-car and Y-car).

[1BadAction]

Any way that I can fix it?

[ScarabEpic22]

Can you seg swap a car trans segment? The only way that this can be fixed is to run a car TCM OS/trans seg, works really well though!

[joecar]

You will need a car trans segment from a file with the same OS as your file...

[1BadAction]

Doesn't appear that I will be able to make it work. OS 12579405

[Taz]

Doesn't appear that I will be able to make it work. OS 12579405

Upgrade to 2004 truck OS 12587603. You will need to adjust the injector tables - your 2003 truck still uses a fuel return line and fuel rail mounted pressure regulator. 2004+ moved to a returnless system.

Then swap in the transmission segments from a 2004 Corvette A4 with the same OS (12587603).


Regards,
Taz

[1BadAction]

Upgrade to 2004 truck OS 12587603. You will need to adjust the injector tables - your 2003 truck still uses a fuel return line and fuel rail mounted pressure regulator. 2004+ moved to a returnless system.

Then swap in the transmission segments from a 2004 Corvette A4 with the same OS (12587603).


Regards,
Taz

Awesome, this sounds like a plan. Thanks guys.

[joecar]

You would have to do something like this:

change your OS to 12212156 from a Camaro/Firebird (auto trans), and manually copy all your tables over.