2012 Yukon shudder/vibration around 1000 rpm and other quirks...

[MmmBrisket]

Hey guys,

I just recently purchased a 2012 Yukon SLT with 57k miles. The car seems to be in great shape overall, but I'm definitely new to the world of Yukons/Tahoes...so I'm hoping you all could offer some expert guidance.

I did do some searching in these forums beforehand about my problem and I'll share what I found below.

Main problem: when I drive on city streets and get to around 30 miles or so and start coasting and the RPMs drop to around 1000 or so...I notice this shudder/vibration as soon as I give it a little gas. It completely goes away at about 1100/1200 rpm.

I kept trying to pinpoint if it was more connected to speed or RPMs and I realized that it was mostly about the RPMs. Even if I'm going 40 or whatever...once it drops down to 1000RPM and I give it a bit of gas, there goes the vibration.

It's not a really strong shudder/vibration, but it's noticeable and annoying. It drives so smooth beyond that quirk and I'd like to get it addressed.

From the posts I've seen, a few have called out:
- Driveshaft alignment
- Torque converter
- U-joint

I'm curious what you all think.

Beyond that main issue, I noticed a few more small quirks:
1) a very slight whining when I turn. Is it normal to whine a bit or could that be a power steering issue surfacing?
2) vehicle start is a little slow in the beginning, almost like the battery is going. It turns over a little slow and then starts right up. I am guessing if I get the battery checked, they'll be able to check the alternator too? Been a while since I've had an issue like this.
3) the vehicle has remote start and it doesn't seem to work if the car has been sitting a bit. but if I click the lock button then hit remote start, it works. I wonder if that's somehow connected to the battery/start issue.

Thanks in advance for any help you can offer!

 

[CaptainAmerica1]

It’s your afm. I. Your dic there’s an option for mode. While driving that mode switches from 4v to 8v or some vernacular close to that. See if the mode changes when you feel the shudder…report back with your findings

 

[gooffeyguy]

I agree, the shudder is from the Active Fuel Management.

As for the remote start, that's how it works. You gotta hit lock then hold the start button a couple seconds.

Sent from my SM-G930V using Tapatalk

 

[MmmBrisket]

It’s your afm. I. Your dic there’s an option for mode. While driving that mode switches from 4v to 8v or some vernacular close to that. See if the mode changes when you feel the shudder…report back with your findings

Cap, are you saying there is a driving mode that will turn off AFM? When I searched AFM for my year online, it seems like articles recommended "delete" or "disable" and both involved some additional parts.

But I'll take a look to see if I have any driving modes.

Thanks for the help, guys!

 

[avalonandl]

No you cannot shut off AFM. You can install a Range device (google it) that overides the AFM and does not let it kick in. You lose about 0.5 to 1 mpg but it prevents it from activating. I use the Range because I have much higher mileage - about 159k miles.

 

[MmmBrisket]

No you cannot shut off AFM. You can install a Range device (google it) that overides the AFM and does not let it kick in. You lose about 0.5 to 1 mpg but it prevents it from activating. I use the Range because I have much higher mileage - about 159k miles.

Ah, got it. Yea, I saw that device in an article I pulled up last night. I'll look into doing that. Thanks!

 

[Foggy]

You can kinda keep the AFM from kicking in: put the gear selector in manual mode,
then put it in 4th gear.. It will shift normally from 1-4 gears... And the afm should
not kick on.. Try that to help pinpoint your issue.
The power steering fluid should be changed.. You can suck out the resevoir
and refill maybe 2-3 times within a week or 2... That should get some of the
contaminants out.
Also, you are now 9 years old.. At that low of mileage, I highly doubt the serpentine
belts have been changed.
You'll need to go thru and change ALL of your fluids and filters. Also spark plugs and
wires. S\
Things go bad/wear over time just as much as mileage. Get that trans serviced
the CORRECT way by dropping the pan and changing the filter.
Front and Rear Differential Fluids. Transfer Case Fluid.
COOLANT... get that old coolant out and replace with new fresh DexCool
You coolant touches everything: don't dismiss it's importance.
And obviously Oil & Filter: use full synth 5w30, and a high quality oil filter
such as wix/acdelco. The number 1 cause for AFM lifter failure is OIL maint.
Oil life monitor is Wrong IMO, change at 50% -- that will be about 3,000 miles or
3-4 months

 

[gooffeyguy]

You can kinda keep the AFM from kicking in: put the gear selector in manual mode,
then put it in 4th gear.. It will shift normally from 1-4 gears... And the afm should
not kick on.. Try that to help pinpoint your issue.
The power steering fluid should be changed.. You can suck out the resevoir
and refill maybe 2-3 times within a week or 2... That should get some of the
contaminants out.
Also, you are now 9 years old.. At that low of mileage, I highly doubt the serpentine
belts have been changed.
You'll need to go thru and change ALL of your fluids and filters. Also spark plugs and
wires. S\
Things go bad/wear over time just as much as mileage. Get that trans serviced
the CORRECT way by dropping the pan and changing the filter.
Front and Rear Differential Fluids. Transfer Case Fluid.
COOLANT... get that old coolant out and replace with new fresh DexCool
You coolant touches everything: don't dismiss it's importance.
And obviously Oil & Filter: use full synth 5w30, and a high quality oil filter
such as wix/acdelco. The number 1 cause for AFM lifter failure is OIL maint.
Oil life monitor is Wrong IMO, change at 50% -- that will be about 3,000 miles or
3-4 months

What if you put manual mode into 5th or 6th, will AFM still activate in those two overdrive gears?

Sent from my SM-G930V using Tapatalk

 

[Foggy]

What if you put manual mode into 5th or 6th, will AFM still activate in those two overdrive gears?

Sent from my SM-G930V using Tapatalk

From what I understand, Yes... in 5th or 6th AFM will kick in even in manual mode

 

[MmmBrisket]

Super helpful list/guidance! Thanks, Foggy!

 

[Geotrash]

As I understand it, when your AFM system is creating this much noticeable shudder, it's likely that the lockup clutch in the torque converter is getting really worn, hence the shudder. When that finally goes, it'll send shrapnel through your transmission, cooler and lines. I just replaced my torque converter with an HD unit that had a billet case and upgraded lockup clutch materials to avoid this problem while doing heavy towing this summer.

 

[wsteele]

Hey guys,

I just recently purchased a 2012 Yukon SLT with 57k miles. The car seems to be in great shape overall, but I'm definitely new to the world of Yukons/Tahoes...so I'm hoping you all could offer some expert guidance.

I did do some searching in these forums beforehand about my problem and I'll share what I found below.

Main problem: when I drive on city streets and get to around 30 miles or so and start coasting and the RPMs drop to around 1000 or so...I notice this shudder/vibration as soon as I give it a little gas. It completely goes away at about 1100/1200 rpm.

I kept trying to pinpoint if it was more connected to speed or RPMs and I realized that it was mostly about the RPMs. Even if I'm going 40 or whatever...once it drops down to 1000RPM and I give it a bit of gas, there goes the vibration.

It's not a really strong shudder/vibration, but it's noticeable and annoying. It drives so smooth beyond that quirk and I'd like to get it addressed.

From the posts I've seen, a few have called out:
- Driveshaft alignment
- Torque converter
- U-joint

I'm curious what you all think.

Beyond that main issue, I noticed a few more small quirks:
1) a very slight whining when I turn. Is it normal to whine a bit or could that be a power steering issue surfacing?
2) vehicle start is a little slow in the beginning, almost like the battery is going. It turns over a little slow and then starts right up. I am guessing if I get the battery checked, they'll be able to check the alternator too? Been a while since I've had an issue like this.
3) the vehicle has remote start and it doesn't seem to work if the car has been sitting a bit. but if I click the lock button then hit remote start, it works. I wonder if that's somehow connected to the battery/start issue.

Thanks in advance for any help you can offer!

I have a 2007 Yukon (kind of the worst case for AFM issues) and I have never had the shudder you describe. I have read others who have had it, so I know it is real and the way you describe when it happens, it sure sounds like your AFM switching from V4 to V8 mode is the trigger.

I turned AFM off on my Yukon with a Diablo Predator 2 tuning device. All the AFM hardware is still there, it just doesn't switch back and forth. I think in later model years like yours, a lot of the AFM issues have been addressed (the ones that may actually lead to a more substantial engine problem), but I don't think they are 100% problem free.

I would also heed what @Geotrash noted about the actual source of the shudder. Maybe have a competent transmission tech take a test drive and see what they think.

Along with Foggy's list of good things to do, maybe consider one of the many ways to turn AFM off in your engine. It might be as little as $50 for an ECM reflash to turn it off, I think most on these threads would consider it money well spent.

Finally, on the slight whining when turning. If your Yukon is 4WD and you have the option of 2WD, Auto, 4WD high and 4WD low, make sure you have it in 2WD and see if it is still whining. If you were in 2WD and get the whining, it is more likely steering than transfer case noise.

 

[MmmBrisket]

You can kinda keep the AFM from kicking in: put the gear selector in manual mode,
then put it in 4th gear.. It will shift normally from 1-4 gears... And the afm should
not kick on.. Try that to help pinpoint your issue.

Spot on! I just tested it out and that's exactly what it is...as I didn't feel the shudder at all. Now to tackle the rest of that list!

 

[MmmBrisket]

As I understand it, when your AFM system is creating this much noticeable shudder, it's likely that the lockup clutch in the torque converter is getting really worn, hence the shudder. When that finally goes, it'll send shrapnel through your transmission, cooler and lines. I just replaced my torque converter with an HD unit that had a billet case and upgraded lockup clutch materials to avoid this problem while doing heavy towing this summer.

Wow, that sounds like a nightmare. I don't think I'll be doing any really heavy towing...but I suppose it would be good to know what you consider "heavy". I'm guessing when I tow, it will likely be 5k or less.

Would that necessitate a HD torque converter? Or maybe I can get by with the standard deal. Going to have my mechanic give it a once over as well.

 

[MmmBrisket]

Not sure how much you all care about pics, but here she is.

 

[wsteele]

Wow, that sounds like a nightmare. I don't think I'll be doing any really heavy towing...but I suppose it would be good to know what you consider "heavy". I'm guessing when I tow, it will likely be 5k or less.

Would that necessitate a HD torque converter? Or maybe I can get by with the standard deal. Going to have my mechanic give it a once over as well.

I towed about 5,000lbs (tandem axle enclosed trailer) quite a bit of the time for about the first 60K miles of my Yukon's life (HD towing package, top brand trailer brake controller, etc.). I had to do an emergency replacement of my transmission (stranded on the highway outside Reno NV) at 76K miles. so...

 

[CaptainAmerica1]

Mines an 07 with 220,000 miles and afm still worked until I tuned it out.

 

[MmmBrisket]

Don't think this is worth starting a separate thread about, but does anyone know what this crazy thing is?

At first I just saw a dent in the quarter panel near the door jam...then pulled the weather strip back (which was loose) and saw a black cap. I easily pulled that off and there was this crazy looking hole drilled.

 

[Foggy]

Don't think this is worth starting a separate thread about, but does anyone know what this crazy thing is?

At first I just saw a dent in the quarter panel near the door jam...then pulled the weather strip back (which was loose) and saw a black cap. I easily pulled that off and there was this crazy looking hole drilled.

View attachment 275815 View attachment 275816 View attachment 275817

That's classic "Paintless Dent Removal" ... They drill holes in unseen areas to
use tools to go in and massage out the dents/hail damage... it's way cheaper than
doing actual body work.... but..... it leaves a hole that can easily rust...

Clean up the area and put some paint/primer on the metal so it doesn't rust.
Then put back in the plug and drive on !!!

As far as your AFM/DOD: if you want the easiest option, get a Range Brand
delete module.. If you want a better driving experience, get a tune.
The guys here love their blackbear tunes... better trans shifting, better performance,
and sometimes better MPG.... either way, get the afm turned off somehow. it leads
to issues

 

[wsteele]

Don't think this is worth starting a separate thread about, but does anyone know what this crazy thing is?

At first I just saw a dent in the quarter panel near the door jam...then pulled the weather strip back (which was loose) and saw a black cap. I easily pulled that off and there was this crazy looking hole drilled.

View attachment 275815 View attachment 275816 View attachment 275817

Maybe a patch left by someone who did some paintless dent repair? (wild guess).