Update on this. This issue seemed to get worse as far as cold start rough idle on both e-85 and 87 octane. Got a decent scan tool and noticed cylinders three and four had misfires. Took it to the dealer and they tested the injectors. They ended up replacing injectors to the number three and four cylinders due to low fuel pressure. So far no more issues.

 

Gonna bump this thread back up...I have a 2014 6.2 with LTs/ory to a 22" magnaflow, airaid MIT with k&n drop in filter, and a khp tune. After its been sitting a while, over night or during the day before I go in on nights, I can start the truck and it will pop through the exhaust. A pretty loud audible pop, now after 30 seconds or so, it'll go away and I get no indication of anything wrong. The CEL will come on and I got it ran last night, it's the P050D code for rough idle on cold start. I fill up at 2 different stations, chevron or shell, since they're the ones that offer 93 instead of 91. The truck runs absolutely amazing, I have no complaints with it except this popping noise it does. Tryin to wrap my head around what it could be but finding info on this code is rather difficult. Any help is appreciated. Here's a video of it

 

I am getting the same thing here, 2014 5.3L Sierra. K&N CAI, and a street tune. The street tuner is going to disable the dual-pulse mode and see if it will fix the issue.

 

every time I run E85 my truck is a little rough on cold starts but never anything crazy, certainly no codes, it just has a rough idle for a minute. I think it's pretty typical of E85 cold starts though

 

Like I found with mine, check for misfires in a specific cylinder and you may have a faulty injector. Most scan tools have this capability., I have read about higher mileage direct injection engines having the issue due to carbon build up, but that was more on bmw's and audis.

 

I have a few misfires at start only, all at 2 or below and goes away after a few seconds. Street tuner did not detect any misfires during normal driving conditions and WOT.

 

Same as mine, I only had misfires on start. Once the cylinder was warm, no issues. It seems in my case and probably yours the injector is flowing, but not enough to light a cold cylinder.

 

you are effing saint!!! monitored my truck today when it was -2c outside, it is the cylinder 7 misfiring like crazy!! as high as 22 from the torque app!

Now... to the dealership... sigh....

 

Hopefully its just that injector then. Have fun at the dealer, lol, let me know what they do.

 

They saw misfire count on cylinder 7 as I have diagnosed from my OBD2, they are replacing the injector now.

Fingers crossed, hopefully this is it!