Shutter/chattering Trans or converter?

[A2013 Denali]

I bought a really clean 1 owner 2013 Denali with 88k on it. I've had it close to 6 months and my wife drives it. IIdont have any seat time in it. But I just drove it 6 hrs to North Carolina and ive noticed at low speed 25 to 30 mph on a flat road. If trans is in high gear I can sometimes get a shuttering feeling. Feels just like I'm on the rumple strips. Is this a converter or trans problem?
If I'm off the gas and eas down on it about a 1/16 just maintain speed is when I can feel it. Can eas down a little more on pedal and it will go away. It has a fine spot. Maybe at the point of it going into OD??
Any ideas?

 

[Sangster]

I also just bought a 20013 Denali with 79k miles on it and it does this exact thing you describe. I'm wondering if it's the V4 to V8 AFM garbage. I'm planning to get that tuned out with a Blackbear tune, but until then it's going ot drive me crazy. Doesn't do it when I put it in tow mode. Just low speed, high gear, barely tipping into the throttle to maintain speed...not even enough to downshift. Just like slight rumble strips/vibration.

 

[swathdiver]

Check to see if you are in V4 mode Danny when driving that way and physically check the condition of your engine mounts.

 

[Bestydahoe]

Sounds exactly like AFM kicking in while the torque converter is locked up in third or fourth gear. Scroll your informant display over to instant fuel economy and watch the V8/V4 indicator while listening for the shutter if it’s in V4 mode during the shutter it’s pretty normal


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[Meccanoble]

Few of us had similar issues and always with very light throttle. Typically a 4th-6th gear situation where rpm's are very low (under 1800). All signs seem to point to torque converter but doesnt mean there isnt something going on in tranny too. Do you also feel a delayed thud when you brake very hard to a complete stop?

 

[Vegasmarc21]

I have had this sensation too, high gear low speed, then shudder/rumble strip vibration. It points to the torque converter...i just put in Dr. Tranny shudder fix and it went away. My suggestion is to get the transmission fluid changed, and most likely the shudder will go away...i went the cheap route with Dr. Tranny shudder fix made by Lubeguard. You can get it at Auto Zone or Amazon...http://www.lubegard.com/~/C-230/Instant+Shudder+Fixx for about 8 to 10 dollars....im mean 4.5 stars out of over 600 reviews can be that bad

 

[Sangster]

I also just added Dr Tranny Shudder Fix AND a bottle of Lubegard and the shudder is completely gone. I'm at 81k miles and will do a transmission fluid change soon. The fluid in there now looked good though.

 

[Sangster]

Update: The shudder came back even with Dr Tranny Shudder Fix and Lubegard. BUT....just got a Range AFM Disabler until I can save up for a BB tune.....no more shudder. So what I thought was the torque converter was actually the 4cyl to 8cyl crap. No more hesitation when pulling away from a stop either. Doesn't seem to have affected my gas mileage yet either.