Not your typical AFM issue

Silver space ship · March 17, 2018

So I'm on my second 2014 5.3 truck first one was a Silverado that I started the Shake or Vibration topic post that I got rid of for a 14 Sierra. I'm very familiar with the how some times the transitions between v4 and v8 or vise versa can be not quite as smooth as I would hope and some are so smooth it's almost undetectable. Put about 13k on my Silverado and 54K now on my Sierra so I have a pretty good idea of what has been normal up to this point. Past few weeks at about 68 mph I will go from v8 to v4 and back to v8 all within a second. started out once every few days and now it happens once a day it seems. One day it did it 4 different times within probably 2 miles. Has done it with cruse on and off. When it does it, it gives the truck the feeling of bang,bang, bang all in about a second time frame. 2 times now it has felt like it's got hung up between the modes, it took about 3 seconds to change over like it stuck doing the switch over. Ive never been really happy with how it feels when it switches over but this is something totally different. Whats going on that's making it do this? Is it damaging the motor when this happens? I have warranty left but no check engine lights so I'm sure I'll get the "couldn't replicate" answer if I bring it in. Thanks.

Johnny01 · March 17, 2018

So I'm on my second 2014 5.3 truck first one was a Silverado that I started the Shake or Vibration topic post that I got rid of for a 14 Sierra. I'm very familiar with the how some times the transitions between v4 and v8 or vise versa can be not quite as smooth as I would hope and some are so smooth it's almost undetectable. Put about 13k on my Silverado and 54K now on my Sierra so I have a pretty good idea of what has been normal up to this point. Past few weeks at about 68 mph I will go from v8 to v4 and back to v8 all within a second. started out once every few days and now it happens once a day it seems. One day it did it 4 different times within probably 2 miles. Has done it with cruse on and off. When it does it, it gives the truck the feeling of bang,bang, bang all in about a second time frame. 2 times now it has felt like it's got hung up between the modes, it took about 3 seconds to change over like it stuck doing the switch over. Ive never been really happy with how it feels when it switches over but this is something totally different. Whats going on that's making it do this? Is it damaging the motor when this happens? I have warranty left but no check engine lights so I'm sure I'll get the "couldn't replicate" answer if I bring it in. Thanks.

Johnny01: I have a 2016 Silverado with only 5000 miles on it.I've had no problems with this issue. But if your truck is having this issue it could damage your running gears. I saw a video on YouTube that shows you how to disable the V4 and run only with V8.

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True North Truckin · March 17, 2018

Can't say I've had that exact issue but out of curiosity are you starting to near your oil change interval? Since these ecotec3 motors all use the engine oil moving through tiny passages to activate and deactivate AFM I have found that once my oil starts to get "used" the afm becomes increasingly rougher in transition. I have found switching from the ac delco semi synthetic a quality full synthetic helps significantly. Perhaps if not already doing so you could give that a try and see if the condition improves?

Silver space ship · March 17, 2018

I'm familiar with the keeping it in manual 5 gear so it can't go into V4 but because of the speed I drive I run at 2500 rpm in 5th so that won't work for me. Also know about the Range programmer that keeps it from going into v4. I don't want to the Range if there's something going on that would make the Range act as a bandaid to mask an issue. I have a feeling it's possibly a solenoid for a lifter that's going out. Id hate to have a breakdown while still under warenty and have the Range detectable and have a claim denied. I think I've read the Range isn't detectable once you pull it but still think it's a bandaid for the issue I'm having right now. If I find my issue is something easy to fix I'd probably get one after my warenty in 5500 miles.

Silver space ship · March 17, 2018

5 minutes ago, True North Truckin said:

Can't say I've had that exact issue but out of curiosity are you starting to near your oil change interval? Since these ecotec3 motors all use the engine oil moving through tiny passages to activate and deactivate AFM I have found that once my oil starts to get "used" the afm becomes increasingly rougher in transition. I have found switching from the ac delco semi synthetic a quality full synthetic helps significantly. Perhaps if not already doing so you could give that a try and see if the condition improves?

I'm right at 50% when I looked today. Last 3 or 4 oil changes have been mobile 1 full synthetic Dextos compatible.

Silver space ship · March 17, 2018

Went to the Range website and it isn't traceable. Might be a way to prevent this issue but still would like to know why it's happening all of a sudden.

Boardmember · March 17, 2018

Dealership. And get the documentation that you’ve had the issue addressed while it is under warranty coverage.

You search TSBs?

Silver space ship · March 17, 2018

8 hours ago, Boardmember said:

Dealership. And get the documentation that you’ve had the issue addressed while it is under warranty coverage.

You search TSBs?

I've looked online for a website that would let me search for tsb on my truck . Unfortunately I'm not having any luck with finding anything that gives me more than just what my outstanding recalls are.