2019 5.3 Suburban Rough idle at stop No Codes Run good though

[Cut Wagon]

‍Other than some type of additive, Probably never have been.

I’ve just drove to Omaha and back for College World Series. The Burb is very consistent. Runs great every where except when in P, or in D at at stop w/foot on brake.

Is there a test I can do to check for torque converter studder?

 

[91RS]

You will not feel torque converter shudder sitting still.

 

[Jake707]

Isn't this pretty common because of the low idle rpm? Read a lot about it when we got our 15. I picked up a cheap diablo tuner bumped the idle up 100 rpm, if I remember correctly, and it idles smooth as butter ever since.

Did you use the diablosport predator X tuner? I was looking at those and it looks like you can adjust the idle, disable AFM as well as input tunes if you want. Doesnt seem bad for $300

 

[Cut Wagon]

Very interested in this.

 

[15burban]

Did you use the diablosport predator X tuner? I was looking at those and it looks like you can adjust the idle, disable AFM as well as input tunes if you want. Doesnt seem bad for $300

It's an intune i2. A guy was selling it for like $100 if I remember right so I bought it. I haven't messed with it too much besides disabling afm and raising the idle. I only drive it like once a month since it's the wife's dd. The little bit of rough idle has always bothered me even though I barely drive it. Just in my own experience every gm truck, mostly friends silverados with the 5.3 around the same years have a rough idle.

 

[Cut Wagon]

I’m a total noob with tuners. I couldn’t tell you a single brand other than the one mentioned in this thread. Which one offers the most bang for the buck? I’m going to get this running well.

 

[Cut Wagon]

As recommended in earlier in thread, I’m trying the BG 44K stuff. I went a step further and had a full BG Induction Fuel cleaning done this morning with the BG machine etc. Cost me $220. Nothing has changed. Idle still rough. I’ll let the BG 44K Platinum stuff do it’s thing for the rest of the tank before I call the service a complete waste.

I was told that no matter if you are in L5 or D, at idle it will go to 4 cylinders and that is what I’m feeling bc 4 bangers don’t idle as smooth as 8 cyl. That is true in general, but I’m still skeptical. I’ve had a couple 4 cyl vehicles and don’t ever recall noticing a rough idle like this. Of course they were Toyotas, so I don’t know.

So maybe that is how the dongle thingy cleans up rough idle? It doesn’t allow it to drop down to 4 cyl at a stop light etc. Anyone confirm this theory?

 

[Cut Wagon]

I keep wondering about the motor mounts and the TSB. Seems to be making more sense. I checked with dealer about them and was told it’s like 7 hrs labor and $1800 to replace the $130 mounts. Have to remove exhaust manifold etc. That’s a lot of money.

 

[OBSandaNNBS]

I keep wondering about the motor mounts and the TSB. Seems to be making more sense. I checked with dealer about them and was told it’s like 7 hrs labor and $1800 to replace the $130 mounts. Have to remove exhaust manifold etc. That’s a lot of money.

I also am hunting a very similar rough idle in my 2012. Haven't thought to try plugs/coils/wires.

I bought a motor mount but haven't done it.

Have you conducted the motor mount tests?
#1 Pry with a pry bar, vehicle OFF. See how much movement you get.
#2 Vehicle on, parking brake on, brake pedal depressed, shift to D, R, P. Rev engine. Note abnormal movement.
$1800 is a lot for non-moving parts.

I tried injector cleaners because mine are loud, no change.
I bought a cheap China dongle, just to bypass afm. No change in idle, BUT, Different generation, GMT900s do not drop cylinders at idle. It should stop yours from dropping @ idle tho. Whether or not that'll help with rough idle, idk.

 

[Cut Wagon]

Yeah I’m hoping a dongle/tuner cleans it up. I would buy one today if I could figure out which one to get.

You going to swap motor mounts yourself? I’m debating that if the dongle delete doesn’t clear it up. This rough idle drives me absolutely crazy.

 

[PPV_2018]

well I don’t know about a tuner dongle, but afm disabler dongles do NOT disallow afm at idle or dfco from my own observation

 

[Cut Wagon]

That’s what I was wondering. Everyone seems to think it does, but I’ve been told at idle it still goes to 4, unless you have an actual tuner, not a dongle.

 

[OBSandaNNBS]

Yeah I’m hoping a dongle/tuner cleans it up. I would buy one today if I could figure out which one to get.

You going to swap motor mounts yourself? I’m debating that if the dongle delete doesn’t clear it up. This rough idle drives me absolutely crazy.

My thought is there is the Range brand disabler @$220 and then there a bunch of Chinese ones. I got a $55 China special and it's worked for a month. See @PPV_2018 post tho on idle.
I Have a 2012, so there are differences between generations. Enough similarities though.
I was planning on doing it myself, if I can't smooth it out elsewise. Idk if it's different between our trucks, but on a gmt900 it's not too bad. You can do it without manifold removal on gmt900.

 

[OBSandaNNBS]

well I don’t know about a tuner dongle, but afm disabler dongles do NOT disallow afm at idle or dfco from my own observation

Hey you learn something new every day!
Building up my K2 knowledge for when I get one

 

[PPV_2018]

That’s what I was wondering. Everyone seems to think it does,

it doesn’t. The range unit has led’s that light up when it’s ‘working’ . . .

When at idle in park, in drive w/foot on brake, or during deceleration, the Led’s fade dim ie: afm disable is NOT in effect. It’s barely noticeable unless it’s night at you’re somewhere with no light.

it has been documented by some here that no aftermarket solution other than a mechanical DOD delete + pcm tune eliminates AFM at all times — same could be said for DFM though i have no hands on experience with DFM disable .

My truck had brand new plugs and wires, and everything else was tip top shape and consistently i still had a bit of a rough idle.

 

[Cut Wagon]

I’m going to do a smoke test at my buddy’s place. At least I can rule that out. When I changed the air filter I noticed one of the screws apparently was over tightened and it doesn’t quite seal air all the way. Most of my vehicles have had at least one clip or fastener that wouldn’t clamp down all the way and it’s never been a major issue. So I will do a smoke test since it’s easy for me to access. I’ll let y’all know results.

 

[OBSandaNNBS]

I’m going to do a smoke test at my buddy’s place. At least I can rule that out. When I changed the air filter I noticed one of the screws apparently was over tightened and it doesn’t quite seal air all the way. Most of my vehicles have had at least one clip or fastener that wouldn’t clamp down all the way and it’s never been a major issue. So I will do a smoke test since it’s easy for me to access. I’ll let y’all know results.

I had one missing! I think you are referring to the airbox screws, that air is upstream of the MAF, so shouldn't cause a vacuum leak/rough idle as far as I'm aware. Replacing the missing screw didn't change mine at all.

 

[Doubeleive]

I have the holley superchips flashpaq f5 on the wifes 16 and a bb tune on my 18, most definitely does not go into v4 mode on either vehicle.
I wouldn't call any cleaning a waste, anything helps on these things
I would be looking at the live data at idle to try and figure it out though
when the wifes 2016 was having a cold start issue I was looking for data like in my video below, misfire counts, coil data, fuel pressure, maf data, etc
same applies for a rough idle. Her's would have a bunch of "minor" misfires at startup then they would go away for the most until restarted again, those do not throw a code unless the count hits a certain threshold, but the truck was not running well, sounded ok for the most part but was a dog. I was mostly checking to see if it was something electronic or if it was a sticky lifter or something could not hear any ticking noises. All of the injectors were replaced and the problem is gone.
you can check the motor mounts by popping the hood so you see the engine and basically power brake it forward or reverse and watch for how much the engine moves. Generally a broken motor mount causes a "clunking sound".
but at any rate I would try and see if anything shows in the live data before throwing more money at it.

 

[Cut Wagon]

Man thanks. That is some good information.

So I drove it about 20 miles yesterday. Today I’ve put about 20 on it and it’s definitely idling smoother than before the cleaning service. Which leads me to think injectors maybe the issue. From what I understand as the BG 44k stuff works it way through a tank then it gets better and better as you drive it. So hopefully I experience that too.

Still going to do smoke test bc I want to make sure I don’t have multiple issues.

 

[Cut Wagon]

Well I ran through the rest of the tank. Filled it up with Shell 89 just see what it would do. After 150ish miles since the BG cleaning service the idle is marginally better, it’s still rough IMO. I’m hoping to do smoke test Friday. Today I went ahead and bought the Blackbear tuning package. I want to take the AFM completely out of the equation before I start digging deeper. Maybe if I’m lucky, deleting AFM plus a tune will smooth out my idle and I can go on with my life. Haha