Now that we have had this Suburban for a couple weeks now I am noticing it's quirks. This thing is smooth as glass for the most parts but there are times when it seems to run just a little rough and it generally is under the same driving conditions.
I had my suspicion that it is when it is either switching to and fro V4 mode and or running in V4.

I finally found the indicator to whether it is in V4 or V8.
And sure enough the rumble I call it is when it is in V4 mode.

I have never driven one of these cylinder deactivating vehicles so I am not sure if it is normal or not.

This message has been edited. Last edited by: Black92LX,

Haven't noticed anything. I believe the indicator is only displayed in the " Instant Fuel Economy" screen

Yes, you can feel the switch from V8>V4. Complaints are more with the A8 transmission than the A6 transmission. Some describe it as a stutter or rumble or motor boat sound in V4. It's more noticeable in some GM vehicles than others. I have a 2016 C7 Z06 Corvette with the A8 transmission and a 2018 Silverado Crew Cab with the A6 transmission. The V8>V4 was noticeable in both.

I don't like the GM V8>V4 technology even though GM says it is seamless and unnoticeable to most owners. I purchased a RANGE module which plugs into the OBDII port and completely eliminates the V8>V4 mode. It will reduce fuel economy to a small degree (1 mpg in my two vehicles).

It is not a 'tune' which can be revealed by a tech. It cannot void your warranty as a 'tune' may cause. It leaves no trace on the computer should you need to take the vehicle into a dealer for warranty. Just remember to remove the device before going to the dealer. I've included the link to the company's website which should answer any questions. They are very responsive to tech questions.

You should buy direct from the company to receive the latest updates. They cost about $200 and they offer reduced pricing periodically. You can purchase with red, green or blue LED lighting. Any updates will be done for free. Note, if you buy from AMAZON or ebay, you may be buying an older version which won't function as well. The older versions also had a tendency to draw down the battery with parasitic draw. The new versions from the manufacturer do not have that issue.

https://www.rangetechnology.com/

Some owners think that the V8>V4 mode contributes to eventual torque converter issues with the constant locking/unlocking with the A8 transmission. The issues of failing converters seems to be more with the A8 transmissions more than A6 transmissions.

GM replaced a lot of A8 Corvette torque converters under warranty for awhile. Then they started double flushing the A8 transmissions fluids as customers complained. They have come out with a newer fluid for the A8 transmissions which GM says will eliminate the noticeable 'stutter' of failing torque converter complaints. Newer GM vehicles with A8 transmissions are supposed to be coming from the factory with the newer fluid.

I can’t tell a difference in my ‘18 Yukon Denali when it makes the switch. And I’ve intentionally tried to notice this in the past.

I've been driving a 2018 Silverado with the 5.3 V8 for a year and a half and if I wasnt watching the graphic go from V8 to V4 and back I would never know the difference. There's absolutely no noise, vibration or anything. My sister in law drove a 2010 suburban for years and there wasnt any discernible difference there either. On the GM forums it seems to be a 50/50 split between those who can tell a difference and those who can't.

Some A8 owners claim they notice the V8>V4 more as mileage increases.

Yes, I can tell between 4 vs 8. I thought at first my driveshaft carrier bearing had gone bad. HP tuner box arriving today. Dod delete kit is the best way to go. Plenty of youtube videos on dod issues.

There is a perceptible change in tone and vibration once you realize when the AFM cuts to V4. Like you, I didn't notice at first until I started using the fuel economy screen.

I occasionally fill up with E85 for a few tanks for the extra power...and greatly decreased fuel economy. One day I had the bed loaded with 1,200 to 1,500 lbs of wood with the transmission in tow/haul mode. The truck was pulling grades at 2,000 rpm in V4 which made for some interesting exhaust sounds.

GM's AFM system is a pain. I bought a turner from Superchips that allows me to go in and shut it off so the truck is in V8 mode 100% of the time.

I’ve never noticed a change other than fuel mileage in my Silverado

I never noticed a change when switching to v4. I do tend to drive with a heavy foot so it didn't happen all that often.

I've never noticed on mine unless I have that info screen showing.

I notice it all the time in my Silverado. It sucks! When I am driving on the highway, when it shifts to 4 cylinders the truck is loud. As some here mentioned it seems like my driveshaft disengaged. Once you are in 4, if you want to pass someone on the highway I find I have to put my foot to the gas to get it back to 8. Maybe a tuner will help.

I've owned a 2017 since new with the afm on a 5.3l v-8 6speed auto.

First 10,000 miles I wasn't too pleased. After that it seems to have learned and/or broken in and runs real nice.

As a passenger, I couldn't tell a difference in my dad's 6.2 Yukon XL Denali (2013 I think).

The Silverados I've driven, mostly 2009-2011 I couldn't feel anything, but they were predominantly new trucks on the lot when I worked there in college.

We have a '14'buban with 5.3 and Borla exhaust which has a noticeable rumble. No real doubt when its in v4 mode as exhaust is throaty then. Weve learned to ignore it.

quote:

Originally posted by az4783054:
Yes, you can feel the switch from V8>V4. Complaints are more with the A8 transmission than the A6 transmission. Some describe it as a stutter or rumble or motor boat sound in V4. It's more noticeable in some GM vehicles than others. I have a 2016 C7 Z06 Corvette with the A8 transmission and a 2018 Silverado Crew Cab with the A6 transmission. The V8>V4 was noticeable in both.

I don't like the GM V8>V4 technology even though GM says it is seamless and unnoticeable to most owners. I purchased a RANGE module which plugs into the OBDII port and completely eliminates the V8>V4 mode. It will reduce fuel economy to a small degree (1 mpg in my two vehicles).

It is not a 'tune' which can be revealed by a tech. It cannot void your warranty as a 'tune' may cause. It leaves no trace on the computer should you need to take the vehicle into a dealer for warranty. Just remember to remove the device before going to the dealer. I've included the link to the company's website which should answer any questions. They are very responsive to tech questions.

You should buy direct from the company to receive the latest updates. They cost about $200 and they offer reduced pricing periodically. You can purchase with red, green or blue LED lighting. Any updates will be done for free. Note, if you buy from AMAZON or ebay, you may be buying an older version which won't function as well. The older versions also had a tendency to draw down the battery with parasitic draw. The new versions from the manufacturer do not have that issue.

https://www.rangetechnology.com/

Some owners think that the V8>V4 mode contributes to eventual torque converter issues with the constant locking/unlocking with the A8 transmission. The issues of failing converters seems to be more with the A8 transmissions more than A6 transmissions.

GM replaced a lot of A8 Corvette torque converters under warranty for awhile. Then they started double flushing the A8 transmissions fluids as customers complained. They have come out with a newer fluid for the A8 transmissions which GM says will eliminate the noticeable 'stutter' of failing torque converter complaints. Newer GM vehicles with A8 transmissions are supposed to be coming from the factory with the newer fluid.

Your initial description is about spot on. The way I would also describe it when driving a manual and you are in 3rd gear but probably should still be in second for a few hundred more rpms. There is just a very light shutter or rumble. No bucking or anything like that but just not smooth.

As for the Range AFM disable I was planning to see what folks said about their AFM experience and transition into that. Lots of very positive reviews on it out there.
I don't want a full tune and still have a bumper to bumper warranty so plug and play is what I am looking for.

Also I a new to these newer GMs so by A6 and A8 I presume you are referring to the 6 speed vs 8 speed transmission? I have a 2015 so I have the 6 speed. Is there a way to display what gear you are in when not in manual mode?
My Expedition shows the gear indicator on the dash at all times I like that but not found that in the setting to turn on.

quote:

Originally posted by Budlum:
There is a perceptible change in tone and vibration once you realize when the AFM cuts to V4. Like you, I didn't notice at first until I started using the fuel economy screen.

I occasionally fill up with E85 for a few tanks for the extra power...and greatly decreased fuel economy. One day I had the bed loaded with 1,200 to 1,500 lbs of wood with the transmission in tow/haul mode. The truck was pulling grades at 2,000 rpm in V4 which made for some interesting exhaust sounds.

I noticed it after a few days of the same type of driving and I presumed it was the AFM which I then located the V4-V8 indicator and confirmed that was what I was feeling.

It's not terrible and on the Highway and the country roads I normally drive it is not a lick of an issue.

Where it comes into play is neighborhood driving between 25-30 it goes to a slight rumble

and 45-50 the same thing and around here if one is not out in the country or on the highway that is where one spends most of the driving.

I am going to see about driving my father in laws 2017 and see if his is as noticeable.

But I highly suspect I'll be picking up a range unit.
Also I love the V8 note and may add an exhaust for a little more throat and I have heard they sound awful when it switches and runs in V4.

I love my Expedition as it is a beast but there is no way to have a good sounding exhaust note from those V6 TTs.

quote:

Originally posted by Black92LX:

"Your initial description is about spot on. The way I would also describe it when driving a manual and you are in 3rd gear but probably should still be in second for a few hundred more rpms. There is just a very light shutter or rumble. No bucking or anything like that but just not smooth.

As for the Range AFM disable I was planning to see what folks said about their AFM experience and transition into that. Lots of very positive reviews on it out there.
I don't want a full tune and still have a bumper to bumper warranty so plug and play is what I am looking for.

Also I a new to these newer GMs so by A6 and A8 I presume you are referring to the 6 speed vs 8 speed transmission? I have a 2015 so I have the 6 speed. Is there a way to display what gear you are in when not in manual mode?
My Expedition shows the gear indicator on the dash at all times I like that but not found that in the setting to turn on.

Yes, an A6 is a 6 speed and an A8 is an 8 speed. The 6 speed has been around for some time and has been quite dependable. The A8 has the torque converter issues I mentioned above.

I recommend the RANGE if you dislike the V8>V4 transition. If you can live with the characteristics and like the little extra fuel economy, you probably don't need the RANGE device in your A6. I installed it my A6 Silverado to eliminate the V8>V4.

The good thing about the RANGE is the same device often fits other GM vehicles with V8>V4 of similar eras. I use the same RANGE model # in my Z06 and my Silverado. If I were to sell either vehicle, chances are it would fit another GM vehicle that I might purchase.

With the RANGE installed in the OBDII port, the 'V4' mode will never be displayed, only 'V8'. I am not aware of any other manner to 'turn off' the 'V4' unless it can be done with a tune. Any tune from factory may be a warranty problem. As I said, the RANGE use is undetectable to a tech unless you inadvertently leave it plugged into the OBDII port. It's not a tune and leaves no history of use.

Diablo makes an OBDII port plug in just like Range does but Range seems to be far more prevalent.
The control modules and also be reprogrammed but I do prefer the plug and play Range option and will likely end up with one.

This may be what I've been noticing.

I don't like it. If it is the cause at least I don't have to worry about something failing or not working as it should.

Has me turned off getting another.