Engine Stuttering at ~1500 RPMs

[headala]

Hey everyone I've looked here and not found any definitive answers on what might be causing this. The vehicle is my 2012 Suburban LT 2WD 5.3L. About 185k miles on it. It is bone stock except for retrofitted headlights and an extra engine to frame ground cable. Oil is changed religiously.

The engine idles okay but on moderate acceleration there is a stuttering around 1000-2200 RPMs. Each time it is a slightly different range of approximately 200RPM within that boundary. The RPM's will flutter up and down a little and there will be a slight loss of power. At first I thought it might be bumps in the road.

There were some old P0300 codes but no misfires when it is actually happening. I had the engine mounts replaced about 1000 miles ago. I believe that it could have been happening before that.

On here I've seen folks saying this type of issue could be any mix of misfires, intake leaks, fouled plugs, fuel pressure regulator, or torque converter/transmission issues. What do you think?

I've cleaned out the throttle body already, but I'm not sure what to try next. I need your wisdom! Should I put in some Lubegard Instant Shudder Fix to see if it's the torque converter/transmission?

 

[Foggy]

You could add the lubegard.. it won't hurt anything
I'm assuming that you've serviced the transmission (?)
Plugs and Wires - How old ?? What Brand???
Fuel ?? Which fuel do you usually use? Are you still using that lately??

Give us a little more info and we can def help out as best as possible over the interwebs

 

[wjburken]

Just out of curiosity, does it shudder when you’re coming back down in RPM’s?

Have you looked to see if the AFM is shifting between V-8 and V-4 or vice versa?

 

[headala]

You could add the lubegard.. it won't hurt anything
I'm assuming that you've serviced the transmission (?)
Plugs and Wires - How old ?? What Brand???
Fuel ?? Which fuel do you usually use? Are you still using that lately??

Give us a little more info and we can def help out as best as possible over the interwebs

Thanks. We had it serviced around 60k ago I believe. Plugs and wires could be original, I don't know how old or what brand.

We typically use the cheap fuel but add a bottle of Lucas additive 2x/month

Just out of curiosity, does it shudder when you’re coming back down in RPM’s?

Have you looked to see if the AFM is shifting between V-8 and V-4 or vice versa?

Definitely does it when locked into V8 mode in M5 gear. Typically it's in V8 when it occurs and isn't transitioning in or out of AFM.

I don't know if it shudders when it comes back down. I will try to drive it tonight if I'm still awake when my wife brings it home. She's on the board of our school and they often go late.

 

[Foggy]

Thanks. We had it serviced around 60k ago I believe. Plugs and wires could be original, I don't know how old or what brand.

We typically use the cheap fuel but add a bottle of Lucas additive 2x/month


Definitely does it when locked into V8 mode in M5 gear. Typically it's in V8 when it occurs and isn't transitioning in or out of AFM.

I don't know if it shudders when it comes back down. I will try to drive it tonight if I'm still awake when my wife brings it home. She's on the board of our school and they often go late.

60K is too long between trans services.. I'd get it serviced the correct way : Drop the pan,
clean everything, install new filter, reinstall pan and fill with Dex VI fluid.

 

[Foggy]

And def install new plugs and wires: AC Delco Irridiums and decent plug wires
My guess is that's the issue with being a P0300 if your stuff has more than 50K on it

 

[headala]

60K is too long between trans services.. I'd get it serviced the correct way : Drop the pan,
clean everything, install new filter, reinstall pan and fill with Dex VI fluid.

OK will do. How often do you do this?

And def install new plugs and wires: AC Delco Irridiums and decent plug wires
My guess is that's the issue with being a P0300 if your stuff has more than 50K on it

What are some brands of plug wires you recommend?

Thanks for the help!

 

[wjburken]

Definitely does it when locked into V8 mode in M5 gear.

Putting your vehicle in M5 does not keep it from switching from V-4 and V-8, at least not when I’ve tried it in my 2013 Yukon XL Denali. Not sure where that rumor originated, but I don’t think it’s true.

 

[headala]

Putting your vehicle in M5 does not keep it from switching from V-4 and V-8, at least not when I’ve tried it in my 2013 Yukon XL Denali. Not sure where that rumor originated, but I don’t think it’s true.

On mine, any of the M gears except 6 will keep it in V8 mode; I've verified this with the DIC.

 

[wjburken]

On mine, any of the M gears except 6 will keep it in V8 mode; I've verified this with the DIC.

My mistake. I was thinking of Tow/Haul mode, not M5. I apologize. Carry on.