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

[Cut Wagon]

Blackbear tune solved my rough idle. AFM is tuned out with idle set at 700. Idles smooth in all scenarios. I highly recommend getting a tune. My Burb is running good and is fun to drive.

 

[Cut Wagon]

Not so fast, it went back to idling rough and was getting worse. Sunday I went to leave and after 5 feet it stalled in my driveway. Traced it to bad camshaft sensor. Replaced with new OEM from dealer and it runs better. In Park, it idles smooth. In Drive at red light/stop sign with foot on brake, it’s rough. Digging deeper.

 

[Cut Wagon]

Thinking motor mounts next move. They probably need to be changed anyway.

 

[Cut Wagon]

So I was able to really sit there and feel the idle yesterday. It’s funny how what you think you feel vs what is really going on. On cold start up, I turned AC off so I could hear and feel. I sat there for 10 minutes observing. Even in Park, I can feel the rough idle. So it’s pretty constant. Also once it’s warmed up and rpm settles down, I would press and hold throttle slightly to raise rpm to like 650 and I could still feel the rough stumbles. It’s faint, but I can feel it. I don’t know what Blackbear did, but I requested idle to be raised to 650 in the tune, however after it warms up, it seems to settle at 500ish. Dunno. At this point it could be a lot of things. Mounts, plugs/wires, injectors, vacuum leak, fuel pump or pressure related, lifters. I’m going to figure it out.

 

[Fless]

Was a CASE relearn done after the cam sensor change? If not, do it just to rule it out.

Might want to look at individual cylinder misfires with a capable scanner.

 

[Cut Wagon]

I finally made it to my friends house for smoke test. Found the boot leaking from duct to throttle body on bottom. I put a flashlight light in it and could see light. I’ve located the OEM duct. Seems there is one with the same exact part number for $186 and one with a new part number for $233. I’m leaning towards the new part number in the hopes of it being updated to fix the deterioration on boot.‍

 

[Cut Wagon]

So I bought the newer part number duct. It’s the same as the old. Still has original part number on the new duct. Anyway it did NOT smooth out my rough idle. Amazing that much of an air leak 3” in front of throttle body doesn’t effect the rough idle. So on to changing motor mounts. May be a few weeks before I get to it, but my offseason is around the corner and I expect to be working on my wagon a lot soon.

 

[mws0019]

I found your thread from a google search and am wondering if you figured this out? I have an 18' suburban with 5.3. Tried all the following below and the idle is NO better. Maybe a little worse at times after the Seafoam because it idles higher now.

inspected air filter-not due for another 20k but will change it anyway when order comes in
Cleaned mass air flow sensor
Changed spark plugs and wires
Fuel injector and fuel system cleaner in gas tank multiple times from multiple brands
Ran sea foam through upper engine
Inspected and cleaned throttle body
Changed PCV valve

Ran smoke test and unable to find a leak. Maybe I am missing a small one and will try again.

 

[Cut Wagon]

No it still idles rough. I’m about change motor mounts, after that, I guess I will look at injectors. Something is causing it.

 

[YukonGold12]

No it still idles rough. I’m about change motor mounts, after that, I guess I will look at injectors. Something is causing it.

Any new revelations on this one? My 07 is doing very much the same thing, and I even changed my engine mounts!

 

[Fless]

Any new revelations on this one? My 07 is doing very much the same thing, and I even changed my engine mounts!

Unfortunately the OP hasn't been on here since last November. Suggest posting your issue in the correct year section.