Getting vibration when AFM is active.

[Adrian92]

Hello everyone, before anything, thank you for taking your time to look at my post and chiming in. Truck is a 2010 Tahoe 5.3L PPV with 188k miles.

As the tittle says, i am getting a vibration whenever my truck has the AFM active. I keep my cluster in the “Instant Econ V4/V8” mode. I’ve been monitoring this for the past week or so. Between the speeds of 30-55mph when the V4 mode is on, i feel a vibration on my gas pedal and steering wheel. But between the speeds of 60mph+ the vibration on the pedal is faint but the steering wheel is the same. However, the moment i tap the gas pedal even in the slightest, that the V8 mode kicks in, all vibration goes away. I have no check engines, no performance issues, no misfires, fluids and oils are perfect, nothing.

This is not something that seriously bothers me like at all, i am just curious what could be causing this and if anyone else has encountered this and found what the cause was. I do have a 2008 and 2016 Yukon XL both 5.3L too and the AFM don’t vibrate like mines does when ON. Looking up online the one thing that comes up the most is motor mounts, but in my experience with bad motor mounts, this doesn’t feel like it’s that, especially since is only when im driving and when im stopped at a light or at idle, there’s no vibration coming from the engine or anything, no kicks either, but i could be wrong. I also know my car is a PPV vehicle so i am not sure if this is also normal. Any opinions/suggestions are appreciated!

 

[Foggy]

Probably the torque converter clutch locking/unlocking and they are known
to go bad in stock configuration by about 110K
You can get some of that tuned out with a reputable tuner who can
turn off the DOD AND make some changes to your transmissions shift tables
and lock up tables that will make your 6L80E SO much more enjoyable to drive
The torque converter "may" already be worn: it throws its clutch material thru
the entire trans requiring a full rebuild if not replaced as preventative maint.

You also could just have vibrations due to needing standard prev maint:
Plugs, wires, Clean TB, Clean MAF, Air filter, dirty engine oil ... etc

 

[tom3]

Our 2019 is also starting to do this but just slightly, 33k miles. When new I couldn't tell it was in 4 or 8 cyl. mode without actually looking at the DIC. I've read that when in 4 cyl. mode those cylinders will run almost at full throttle until the V8 mode comes back on. Can't be good on those parts I think. I'm pretty much living with it until the extended warranty runs out.

 

[j91z28d1]

while it might be normal, afm in general is a failure waiting to happen. I would have to turned off in the ecm as soon as possible.

 

[Marky Dissod]

Our 2019 is also starting to do this but just slightly, 33k miles. When new I couldn't tell it was in 4 or 8 cyl. mode without actually looking at the DIC.
I've read that when in 4 cyl. mode those cylinders will run almost at full throttle until the V8 mode comes back on. Can't be good on those parts I think.
I'm pretty much living with it until the extended warranty runs out.

When in Engine 1/2@$$ - when the ecm decides that 4 cylinders is better than 8 -
the throttle blade does open further than it would if all 8 cylinders were sharing the work equally.
IN THEORY, the wider the throttle is open, the better the BSFC. Whether or not this is true,
in practice, there are several sacrifices made that erase this benefit over time for the end user.

Think about this. Prior to Engine 1/2@$$, all 8 cylinders always worked together equally.
When in Engine 1/2@$$, 4 part time cylinders take a break and cool off,
while the full time 4 cylinders work even harder than when all 8 are working equally together.
Think about this long enough, you'll disable Engine 1/2@$$ mode at your first opportunity.
HINT: why were early Hemis with Engine 1/2@$$ cracking blocks?

The vibration you're feeling is the torque converter clutch wearing out.
GM locks the TCC differently in V8 mode vs V4 mode (PulseWidth Modulation I think)
so that no one inside the vehicle feels or notices V4 mode.
But the TCC pays for this, and when it finishes wearing out, it takes out the rest of the 6L80 with it.

6L90s which are never coupled to engines with V4 mode tend to last longer than 6L80s.
Hopefully your extended warranty covers your 6L80.

 

[Adrian92]

Probably the torque converter clutch locking/unlocking and they are known
to go bad in stock configuration by about 110K
You can get some of that tuned out with a reputable tuner who can
turn off the DOD AND make some changes to your transmissions shift tables
and lock up tables that will make your 6L80E SO much more enjoyable to drive
The torque converter "may" already be worn: it throws its clutch material thru
the entire trans requiring a full rebuild if not replaced as preventative maint.

You also could just have vibrations due to needing standard prev maint:
Plugs, wires, Clean TB, Clean MAF, Air filter, dirty engine oil ... etc

Hey man thanks for the input and suggestions. Sorry i took long to reply, for whatever reason i wasn’t getting notified of replies. Anywho, so far since i bought the car i always change the air filter and did an oil change like a month ago, 5w-30 Mobil 1 High Mileage and the OEM ACDelco filter. The only thing i haven’t done is a spark plug change beacuse i will be honest, i’ve been avoiding that far back passenger side one -_- serious PITA when i change them in my 08 yukon XL and since mines haven’t presented any misfires or performance issues, i have left them alone for now but i guess i will have to tackle them eventually. But what you said about the torque converter clutch is interesting and will see what i decide to do with it if the spark plugs aren’t the answer.

 

[tuckerrnr1]

When I had my 2010 Suburban, the Range AFM disabler plug in module got rid of that vibration. Disabling that I think also helped me get 180,000 miles out of the original transmission.

 

[Adrian92]

When I had my 2010 Suburban, the Range AFM disabler plug in module got rid of that vibration. Disabling that I think also helped me get 180,000 miles out of the original transmission.

I have 187k on this one. And yeah the vibration goes away the moment it switches back into V8. I did looked into these obd plug-ins a while back but decided not to go for them since most of them in their reviews eventually led to the same problem(s), limp mode, check engine, stabilititrak problems, misfires, etc. and this was in all price ranges. I don’t however, recall seeing that one you mentioned, a quick google search shows americantrucks carries them but there’s 2 types, a red and blue one, which did you try if you don’t mind me asking and any problems so far?

 

[tuckerrnr1]

Range Technology RA003B AFM/DFM Disabler-Blue

Our patented technology is the only product that will disable Active and Dynamic Fuel Management without reprogramming the factory ECU. Full power delivery all the time without factory warranty concerns. *It is suggested the device be unplugged if the vehicle is not being driven daily or left...

www.rangetechnology.com

I believe this is the one I have and chose the blue LED as I prefer the color. I used it in that suburban for six years and moved it to the 2016 when I got it, two years and zero issues.

 

[Adrian92]

Range Technology RA003B AFM/DFM Disabler-Blue

Our patented technology is the only product that will disable Active and Dynamic Fuel Management without reprogramming the factory ECU. Full power delivery all the time without factory warranty concerns. *It is suggested the device be unplugged if the vehicle is not being driven daily or left...

www.rangetechnology.com

I believe this is the one I have and chose the blue LED as I prefer the color. I used it in that suburban for six years and moved it to the 2016 when I got it, two years and zero issues.

I appreciate it Tucker! And it’s good to know you had that one for that long and on 2 different cars and still working. Also thanks for the link, always a better choice to order straight from the official site!