2016 stumbles hard on regular gas but not on premium

[Supersonic]

My wife drives a 2016 GMC Sierra with about 15k miles on it and I almost never ride in the truck but the other day I hopped in it and noticed once it was warm it would stumble hard, actually fall on it face right about the time it should shift gears from 1st to second. It’s even worse when it’s hot outside or if the air conditioner is on. I then decided to fill the truck up since I had run some gas out of it and filled it with premium and all the stumbling went away. Once the premium was gone we refilled with shell 87 octane and the stumble came right back. This isn’t just a little flutter either, it feels like the truck just shuts off for a second or two. Everything is bone stock and the truck has low miles. I called the dealership and of course they told me this is the first they have heard of a problem like this?. When I asked the wife about it she said,” oh it’s always done that”... anyone else experience this? Feels like it’s fuel or timing related, not a transmission issue. I do not like the idea of having to pay for premium fuel for the life of this truck when the owners manual recommends 87 octane....

[BriDroid]

My 18 5.3 runs way better on 89. It’s not quite as bad as your wife’s on 87, but I can tell a huge difference when I run mid grade. Idle is WAY smoother and takeoff is much smoother too.

[CamGTP]

Try mid grade is I'd do too. I only run 89 or sometimes 88 because it's E15 (have a sensor in my truck) or just E85.

[Sierra Dan]

13 hours ago, BriDroid said:

My 18 5.3 runs way better on 89. It’s not quite as bad as your wife’s on 87, but I can tell a huge difference when I run mid grade. Idle is WAY smoother and takeoff is much smoother too.

+2 on 89 octane over 87. I see no difference when running premium over 89 other than higher cost.

E85 for me April through October. My Sierra loves it.

[Supersonic]

But does anyone have any idea why this is happening? It has to be something that’s adjustable. Timing? Fuel curve? An almost new $60,000 truck shouldn’t be doing this on its recommend fuel. 

[BigBadSierra]

Use a can of CRC GDI  the stumble will stop.

[jay webb]

On 6/13/2019 at 6:42 PM, Supersonic said:

My wife drives a 2016 GMC Sierra with about 15k miles on it and I almost never ride in the truck but the other day I hopped in it and noticed once it was warm it would stumble hard, actually fall on it face right about the time it should shift gears from 1st to second. It’s even worse when it’s hot outside or if the air conditioner is on. I then decided to fill the truck up since I had run some gas out of it and filled it with premium and all the stumbling went away. Once the premium was gone we refilled with shell 87 octane and the stumble came right back. This isn’t just a little flutter either, it feels like the truck just shuts off for a second or two. Everything is bone stock and the truck has low miles. I called the dealership and of course they told me this is the first they have heard of a problem like this. When I asked the wife about it she said,” oh it’s always done that”... anyone else experience this? Feels like it’s fuel or timing related, not a transmission issue. I do not like the idea of having to pay for premium fuel for the life of this truck when the owners manual recommends 87 octane....

1st off do you have a 6.2 engine? if so it requires premium fuel.