Looking for some 6T75 help

Attachment 156098

2012 gmc Acadia with all the usual tcc shudder issues. The tune I attached is working the best of all the ones I've done so far, but still having some issues with 5 & 6 leaving tcc lockup. I left the stock apply/release and desired pressure table. I added some increases to the apply ramp and zeroed out slip in 5/6. The problem I mostly get is a somewhat harsh tcc engagement in 5th at low rpm and an occasional strange feeling of a sudden drop coming out of 6th to 5th on an incline under light load. Under load seems fine and no fluctuating tach at highway speeds like original tune.

Any suggestions?

What do you mean by "drop"? Do you mean a harshness or a jerk?

Try these TCC settings.

Russ Kemp

Yes, like a pause then suddering downshift until power comes back or it hits 4th gear.

Thanks for the file Russ K! I see you altered the desired pressures and left the ramp stock. You also set 5 & 6 apply/release at 43/40. I will load this and give it a try. One thing that perplexes me is the tcc adapt row where torque min is 22 ft/lb.....but torque max is 15 ft/lb. These are the stock settings and I see you left them alone. These settings to my mind seem like they cancel each other out?

So I'm still having trouble with this vehicle and adjusting the tune. After doing some graphing and reviewing in vmscanner what's going on is that in 5th or 6th under a light throttle at cruising speed when encountering a load like a gradual uphill, the tcc line pressure drops off and a huge slip occurs. The tcc line pressure then tries to ramp back up and lock everything down - which usually occurs if throttle is backed off or the incline levels out. Seems like there is a table or some other parameter coming into play that's knocking down the tcc apply pressure at those times of engine load. Any clues??

Try these TCC changes. Do you have any misfire DTC's?

Russ Kemp

Thanks Russ, I'll try it!

I have no misfire dtc's present.

Can someone take a look at my scan file. This particular one is a quick scan in 6th with tcc locked. My tcc line pressure dips to zero and massive slip occurs. Any ideas are welcomed.

Still experiencing frustrations with trying to leave 5th & 6th tcc lock in place. Problems are occurring with steady/light throttle at cruising speeds then encountering a slight load or applying a bit more throttle. When looking at logs and going off the driving feel, it seems to me like the car is on a threshold of a downshift, so something tells the tcc to unlock....but then instead of a shift it just lugs and tcc engages again. This is giving me slips and bangs with a log graph that shows zero tcc line pressure at those spikes. I've fiddled with some shift parameters but didn't notice any difference so I returned those settings. This vehicle is using the #24261871 O.S.....and I thought i read somewhere there was an issue with it.

Any thoughts?

I have a '12 Enclave AWD and am trying to eliminate a shudder. I did three drains and fills and added the Lubegard shudder fix on the last fill. Hopefully, I can get this to go away with a tune.

So....I'm one of the lucky ones that has a bad torque converter and no amount of tune is going to fix. I currently have it disabled in all gears until I can change it, and I'm just avoiding highway speeds. If I had to guess mine is probably warped and/or missing the lining. If I try leaving 5th & 6th engaged it pulls down the engine rpm then slips/catches in an annoying fashion. VCM scanner shows spikes everywhere during the slips. In the meantime I added a trans cooler - which will also be helpful after the repair.

Quote:

---

Originally Posted by riverside21

So....I'm one of the lucky ones that has a bad torque converter and no amount of tune is going to fix. I currently have it disabled in all gears until I can change it, and I'm just avoiding highway speeds. If I had to guess mine is probably warped and/or missing the lining. If I try leaving 5th & 6th engaged it pulls down the engine rpm then slips/catches in an annoying fashion. VCM scanner shows spikes everywhere during the slips. In the meantime I added a trans cooler - which will also be helpful after the repair.

---

Sorry to hear that, that sucks! Hopefully, I won't have to replace my TC, but I will if I have to.

I copied what Russ put in his first hpt file and mine is doing pretty good. I can still get some shudder in 5th but, I don't feel it in 6th.

Wondering if I should change the 5th gear too.

Quote:

---

Originally Posted by Russ K

Try these TCC changes. Do you have any misfire DTC's?

Russ Kemp

---

Will this file work for an 08 Acadia AWD?