V4 to V8 driveability issues.

[mookdoc6]

 

+1 on my 2015. Seamless. I am as retentive as they come and it is imperceptible.

I like that! Mine is a 2016 and it's almost imperceptible on mine.....If it's off I am sure its bothersome and in a couple more years you will never even know it's doing it?

[glcbn]

I'm don't know about 15's but it's completely seamless on my '16. I can't tell it's switching unless I look at the DIC. Hope you get it resolved.

 

Same with my '14, and it was this way from day one. Never any issues.

[Havvkeye]

I'm don't know about 15's but it's completely seamless on my '16. I can't tell it's switching unless I look at the DIC. Hope you get it resolved.

Same here as well. I have to look to know.

[Jake56]

Same here can't feel it change (and my 2014 more base options did not include indicator to let me know)

[flasch192]

my 16 surges a little when going from 8 too 4 , you can see the tach jump .....

[SouthernSilveradoGuy85]

II can't feel when it switches in my '14. Before I had the exhaust done the only way I even knew it was in V4 mode was by looking at the DIC.

 

The clunking could be a common problem which is the rear axle u-bolt nuts not being tight enough. I TQed mine to about 79 I believe and I had to do over 1 full turn on all of them. Clunking stopped.

[jjvito]

pretty seamless on my '16..felt it maybe 2 times at most during the first 4 months of owning it. Both times I recall feeling a stutter was on the highway in slow paced traffic

[alcarames]

I guess it depends on the road I'm on. It's usually more noticeable or worst when going up hills or when the person in front of me continuously slows down.

 

I usually drive at part throttle like most people. So if I go downhill at part throttle the V4 mode engages now I'm going uphill same throttle position V4 mode still engaged the computer loses its mind won't switch into V8 mode and now begins this strange stuttering vibration and when it finally goes into V8 mode there is a violent clunk from the trans and driveshaft.

 

I also think it has to do with the gear the truck is in. So as I said going downhill it's probably in OD but now I begin going uphill it's still in V4 mode and in OD.

 

I think having to mash the gas every time this occurs to prevent this from happening defeats the purpose of fuel efficiency to begin with.

[edgexcsp]

For the most part I don't notice it on my 16' but in certain throttle positions it does surge a little. It's an annoyance for sure but not the end of the world, I think it bothers me more that I never felt the V4 mode in my 2008...

[Thomcat]

I purchased a 2016 GMC sierra and I thought I was going to hate the AFM but it is seemless in this model year. I cannot tell when it is in v4 mode without looking at the display. I also noticed that it drops out of v4 mode almost immediately when the slightest throttle is applied. The earlier versions were likely staying in v4 mode longer and causing weird harmonics under part throttle conditions. This makes me think that GM could reflash the system to eliminate your problem. Unfortunately I believe they compensated on the 2016 models by holding it in a higher gear longer in an effort to keep rpm's as low as possible. Occasionally I come out of a curve and attempt to accelerate lightly and there is an audible drone as the engine labors in far too high of a gear. I initially thought it was the AFM but its not. Its in v8 mode it simply in too high of a gear. ...

X2

The transition on mt '16 is seamless; can only tell V4 operation by the display or change in exhaust pitch when windows are down; much better V4/8 programming than the 5.3l 6 spds. in my previous GMs.

[GMCustomerService]

Good morning alcarames,

We greatly appreciate your loyalty to GM. However, I do regret to hear that you are experiencing these drivability concerns. I would be more than happy to set you up to get this diagnosed at a dealership. If you would like my assistance, please feel free to send me a private message.

All the best,

Julianne M.

GM Customer Care

 

I guess it depends on the road I'm on. It's usually more noticeable or worst when going up hills or when the person in front of me continuously slows down.

I usually drive at part throttle like most people. So if I go downhill at part throttle the V4 mode engages now I'm going uphill same throttle position V4 mode still engaged the computer loses its mind won't switch into V8 mode and now begins this strange stuttering vibration and when it finally goes into V8 mode there is a violent clunk from the trans and driveshaft.

I also think it has to do with the gear the truck is in. So as I said going downhill it's probably in OD but now I begin going uphill it's still in V4 mode and in OD.

I think having to mash the gas every time this occurs to prevent this from happening defeats the purpose of fuel efficiency to begin with.

[alcarames]

Although I appreciate your effort to help. I've already been to the dealer for this issue three times. I have an open case with GM and nothing has happened.

 

Dealer can't do anything because there are no open tsb's or check engine lights. GM has said the clunking and vibration and stuttering are all "normal vehicle characteristics".

 

Dealer has admitted that many customers come in for this same issue. They've even told me to try and change how I drive to avoid these issues. I drive my other vehicles the same and don't experience any clunking or vibration. The frustrating thing is the sticker on the truck was over $54k and this is "normal vehicle characteristic".

[ws6guy]

I've been driving a loaner 2016 while my 2013 is getting some warranty work done. I only notice the V4 /V8 transition at slow speeds while in 2nd to 3rd gear. What I do notice is the truck wants to surge funny when accelerating from a complete stop. I think the transmission is shifting to 2nd and 3rd too soon then downshifts momentarily.

 

So far I've had this truck for 2 weeks which has the 5.3l in it and compared to my 2013 with the 4.8l and 4sp I'm getting 1.5 to 2MPG better mileage. I'm not sure of all this transmission and AFM business is worth it to me. I think I'm going to hold on to my 2013 as long as possible!

[oneandzero]

Although I appreciate your effort to help. I've already been to the dealer for this issue three times. I have an open case with GM and nothing has happened.

 

Dealer can't do anything because there are no open tsb's or check engine lights. GM has said the clunking and vibration and stuttering are all "normal vehicle characteristics".

 

Dealer has admitted that many customers come in for this same issue. They've even told me to try and change how I drive to avoid these issues. I drive my other vehicles the same and don't experience any clunking or vibration. The frustrating thing is the sticker on the truck was over $54k and this is "normal vehicle characteristic".

Dealer fixed mine with a Diablo tune. No more V4 and now shifts as it should.

[alcarames]

How did you get them to do that with a Diablo tuner? Do you still have warranty?