17 gmc Denali 6.2 had Issue with trans shudder. It was in 2 years go. Dealership have tech bullentin said needs to flush trans fluid to stop the shudder. After serviced that. Fine for 2 years until now I feel trans shudder again. Need to go dealership to have trans machine flush or should I do it myself drain old fluid off then put in new one?

mobil lvp trans fluid. Which your suggestion. Let shop do flush trans ? I don’t want change torque converter. I was hope flush can help? Need your feedback k.

 

Gotta drop the exhaust to drop the pan.

 

What about flush machine

 

A fluid exchange machine would work just fine to replace all the fluid with new stuff. I think GM says that you need like 20 quarts when they do it that way.

 

Just flush it again, with the same new mobil fluid.

Most likely the additive package is starting to break down and that's why you're feeling the shudder again.

Your trans likely takes around 12 quarts, dropping the pan and filter will only get about 4 quarts. I have a 6L80 and when I drain the pan I get 4 quarts. That's why the flush is so much better, it exchanges all the fluid.

 

Took my 18 into the dealer a few weeks ago for this also, they told me they used 30ish quarts to flush it 3 times then fill. Not sure if thats true or not but the issue was fixed when I got it back. Also heard if you update the tune and up converter pressure the problem is fixed permantely.

 

That sounds about right. I've heard that they do use up to 30. I did that on mine as well but a different deal.

I bet the new fluid along with the updated programming/tune is a great fix.

 

Update flush done and its back normal. Need tune transmssion bad I dont like lack of time response throttle and shift point.

 

Reset trans adaptives and drive it normal for a few days and see how you like that. You'll need a good scanner to do it, or take to dealer and ask them to reset adaptives, or disconnect battery over night (i've always used a scanner to do it, I assume disconnecting the battery for a good while will do it but I haven't tried it)

Those transmissions shift great but the adaptives may be funky right now since it was trying to adapt to old fluid. Now that it has fresh fluid it needs to relearn shifts etc.

And from what I understand, it's best to leave the trans tune alone and just up the shift points and take the minimal amount of tq management out in the pcm tune and they shift great. I may be wrong but I believe that's what most tuners are doing for good shifts and trans longevity (mostly leaving the trans alone)

 

the dealer will do it 3 times for free then replace converter. it takes 20qts of the new Mobil 1 HP. then ya do trans clutch relearn. anyone with a HP MPVI2 can do it.