My 07 5.9 twice now in the last week upon cold start up ran really rough for awhile until warmed up. Kitty ran away prior to this problem, could this have affect on it ??? Is so why and if not any ideas as to why this could be happening all of a sudden. Other mods listed and has approx 3700 miles on it.

 

If it wasn't plugged in for a fair bit of time, its normal. All diesels are cranky when you start them up in the cold and they haven't been plugged in. I know my 1st gen sure lets me know in -25C that its hating life when I start it up cold. I would've plugged it in but I didn't have an outlet. Cold starts are hard on these engines and if you can, avoid them. When you get some more miles on your rig, put in some 15W40 synthetic to help with cold start ups and get the oil pressure up faster. Do that and plug it in when the temps require it and you should have no problems.

 

My dads 07 5.9 has a terrible idle in the morning and it isnt that cold down here. once it warms up its fine. Bone stock and no additives.

 

Could be a problem...maybe take it back to the dealer and see what they say. I've started mine plenty of times in sub-zero weather without being plugged in and it runs and idles smoothly.

 

Taking mine in this week for possible idler pulley replacement. It starts fine when it's cold but squeaks, and dosen't sound quit right through the exhast when high idle kicks in. Only have 1600kms on it. Squeaky belt goes away when it's warm, and it sounds fine at high idle as well.