Rough Starts when cold out

[s022mag]

Hello everyone new to the forum, use to be a member at ls1.com for my SS but did all I'm ever going to do to it. Now I have a 02' 2500HD 6.0 and only concerned with power for towing. I bought the truck early spring of this year and over the summer havent had any major trouble with the truck. I had a few issues were the eng temp got over 210 just from sitting in traffic or in a drive thru but it has always dropped and never got any higher.

My recent trouble is with the cold starts in the morning after the truck has sat over night. To my knowledge there is nothing as far a power adds to the truck. It starts up fine and runs ok for few seconds but when it idles down it starts and some times stalls. It restarts fine and idles high around 1500rpms for a few seconds and when it drops below 1k rpm it runs rough. I have to keep my foot on the gas for awhile and then it will run a little better. After a while it runs fine and I don't have any problems with it. Never had any issues with it starting in the summer, only in the winter.

I have a block heater on it but haven't used it, didn't think it would make much difference. I believe fuel filter has been replaced in spring ( not sure if that would be the cause) and so have the plugs and wires.

Any help would be appreicated.
Matt

[oleshifty]

I had similar problem.... turned the screw on the tb butterfly a 1/2 turn and everything was fine. I have an aftermarket tb, so i'm assuming the 2 metals expanded at different rates or something with the cold.


If you don't have a check engine light, i'd start there, and maybe throw a bottle of HEET in the tank just to be on the safe side.

[txarkitekt]

Its just the typical carbon build up in the cylinders on these motors. Most people call it "piston slap." It is just years and miles of carbon build up. It doesn't hurt anything.

You could run Seafoam or another type of combustion chamber cleaner.