Engine "missing" On Start Up

[Mossyoakglock]

When I start my truck in the morning, it has a rough idle for about 4-5 seconds and then stops. It idles like it's missing and is a little rough, but not that bad. It's just enough that I can feel it. It only does this when I start. Once I put it in drive and drive around, sitting in traffic, idling, etc it doesn't do it. It just started this about a week ago so I think it could be bad gas. I'm going to run some seafoam through it on the next tank to see what that does. Any thoughts on what it could be?

[Tsmith]

Brett my brand new GMC 5.3 liter has done this very thing like 5 times. Oddly and it could be a total coincidence if I press the accelerator pedal one time before starting it doesn't seem to do this. I've only put one tank of gas in it myself, BP brand but will keep an eye out and see if it does it anymore.

[Mossyoakglock]

Not sure if yours does this too. I'll leave during lunch and it might do it for a few seconds like in the morning, but when I'm done with lunch, trucks sits maybe 45 min, it will not do it. It only does this in the morning and never does it throughout the day when driving the truck.

[Tsmith]

Mines only done it after its sat overnight. Totally cold engine.

[Silverado4x4]

From what I have heard and read the rough idle is due to the lean fuel/air mixture needed at idle to meet the most stringent emissions requirements.

[bubba33]

mine does it too after it sits over night.And the first shift into second is hard,Then everything is back to normal.

[tdm156]

I am having a bit of that myself. Same type of rough idle then goes away once I rev it up once or start driving. Wonder if the summer blend of fuels that are out now could have something to do with it? Could be the running lean at start up with the active fuel management and it takes it a minute or so to even out? Just a thought and figure I will ask next time I am by the dealer

[slmnow]

Had the same issue on my Nissan pickup a while back. Ended up being a stuck EGR valve.

[hardrock]

I have an 09 Chevy with a 5.3 and it does the same thing almost every morning on startup. It takes about 10 seconds to go away and everything is fine afterwards. Any other time I crank it, its normal, only on a cold start in the AM.

[georgecdisc]

Could be the running lean at start up with the active fuel management and it takes it a minute or so to even out?

AFM is not used at idle

[Tsmith]

Um, starting to seem like its a normal experience ...

[Mossyoakglock]

It seems that way, since mine only does it on a cold start in the morning, or when it's been sitting for 6-7 hours.

[BlackOut V8]

my new truck does this aswell. Sits overnight, a bit of a cold crank start and then it will smooth out. Must me all the oil running down to the pan overnight. I run synthetics. Oil viscosity? Anyone else run synthetics and seem to have this "cold crank start" issue?

[hardrock]

Mine only has 3K miles and hasn't had an oil change and it has done it since I brought it home from the dealer. I think it is just the truck. Everyone I have talked to has the same issue. Its not a big deal, I suppose, it just sounds terrible for a brand new truck to sound like an old worn out old 305 2bbl with 250k miles on it when you crank it, lol.

[crepitus]

It seems that way, since mine only does it on a cold start in the morning, or when it's been sitting for 6-7 hours.

mine has starting doing the recently as well. never noticed it before. just turned 9k miles. i get to work around 7am and goto lunch around 1 so with a 6 hours of sitting time it does it.