2008 GMC Tow/Haul shift points

[nonebetter]

Truck wont shift at 6000 shifts a 5200. Shift set at 6200rpm. The 6200rpm shift is with tow/haul off the 5200rpm shifts is with tow/haul on.

[Bill@HPTuners]

post tune & scanner log.

[nonebetter]

Anything Bill?

[vortec]

I noticed this along time ago,if youtry to change the values in the performance tab,the changes do not apply!They remain the same as stock for some reason.

[Bill@HPTuners]

Anything Bill?

Can you please post your stock tune so I can view the changes that have been made, nothing in the file looks off so maybe its something deeper in the code or something I'm not seeing.

[nonebetter]

This is how it came from gm.Attachment 16169

[RCSBcolo]

i noticed the same thing...just stopped using the tow haul mode...but would be nice if I could use it.

[LSX378]

Is it shifting at the correct MPH?

[Mep_q8]

I get the same thing on my '08 yukon.. just tuned the normal for my shift points and TM...

[Bill@HPTuners]

New beta fixes these issues, please contact support at hptuners.com with your serial number & a link to this thread for access.

Thanks,
Bill

[thesubfloor]

New beta fixes these issues, please contact support at hptuners.com with your serial number & a link to this thread for access.

Thanks,
Bill

Will this also fix the problem with the A6 transmission where it only shifts based on MPH and not both that and RPM like it's supposed to?

If it doesn't fix that yet, any update on when it will?

Thanks,
Christopher

[Bill@HPTuners]

Will this also fix the problem with the A6 transmission where it only shifts based on MPH and not both that and RPM like it's supposed to?

If it doesn't fix that yet, any update on when it will?

Thanks,
Christopher

The A6 uses a completely different controller so this update does not affect the A6 in any way.

With that said we are still looking into what you are referring to.

[thesubfloor]

The A6 uses a completely different controller so this update does not affect the A6 in any way.

With that said we are still looking into what you are referring to.

Does that mean you're not sure what I'm talking about or that you do know what I'm talking about but just haven't found what's causing the problem in the first place?

[Bill@HPTuners]

Does that mean you're not sure what I'm talking about or that you do know what I'm talking about but just haven't found what's causing the problem in the first place?

I assume you are talking about this http://www.hptuners.com/forum/showthread.php?t=20534

[thesubfloor]

I assume you are talking about this http://www.hptuners.com/forum/showthread.php?t=20534

Yep, that would be the one.

Just trying to keep you guys on your toes...

[LSX378]

Yep, that would be the one.

Just trying to keep you guys on your toes...

On this shift problem, do you have TM turned off/reduced?

[thesubfloor]

On this shift problem, do you have TM turned off/reduced?

Was this question directed at me or the OP? If it was for me, the same thing happens regardless of whether TM is on or off.

[LSX378]

Was this question directed at me or the OP? If it was for me, the same thing happens regardless of whether TM is on or off.

Yes the A6 mph/rpm shift "problem". Our understanding is that the mph table is used first, and then if VSS fails, the rpm table. Not confirmed.

We also have noticed that with TM off, shifts can get held up at WOT because the torque is too high.

[thesubfloor]

Yes the A6 mph/rpm shift "problem". Our understanding is that the mph table is used first, and then if VSS fails, the rpm table. Not confirmed.

We also have noticed that with TM off, shifts can get held up at WOT because the torque is too high.

My car will shift just fine at WOT with TM off, just not based on the RPM settings.