rough idle, white smoke on startup please help
 

Every morning when I cold start the truck it fires up and blows massive amounts of white smoke and the idle shakes the whole truck and it seems to be missing one or two cylinders. during this time I have close to no power. but after the engine warms up it runs fine and smoke disappears and starts fine after that. I have also experienced a drop in fuel economy. I just had the head gaskets done and new valve seats. The truck did not have these symptoms before this. Truck is a 2005 with 172,000 miles. could this just be as simple as losing prime overnight? could it be injectors even though balance rates checked out to be fine? The problem is only getting worse so any help would be appreciated.

is the white smoke water or fuel? they can look very much the same.

if it was mine i would, on a cold engine, remove the glow plugs and pull the FCIM fuse (so it doesn't inject any fuel). then have someone crank the engine over while watching the glow plug holes. if you get water coming out of any of the holes then the gasket was incorrectly installed and leaking. if it is fuel coming out then it is a leaky injector.

cant think of anything else that would go away after warming up. have you inspected the #2 & #7 injector harness and connectors. these are known to be an issue on the LLY. google "LLY ice pick trick".

have you monitored the desired and actual fuel pressure while it is running like this?

It is definitely not water. Smells strongly of fuel. Also not eating any coolant. I don't have anything to monitor rail pressure but when I took it in they said rail pressure was normal. I will check the wiring harness though. Is there a easy way to check for a leaky injector without sending them to be tested? I'm starting to think this is probably the issue.

the above test will tell you what injector is leaking. fuel mist will shoot out of the glow plug hole when there should be none

it is basically what these guys did. make sure you pull the fcim fuse so the computer can't open the injectors.

I have a '97 cummins and it did that every time I started it this winter. Nothing was wrong it just had to heat up.

Apple and oranges here.

Duramax is quite a bit different then the 12v cummins. V8 vs straight 6, upto 26 thousand PSI injection pressure vs a a few thousand and glow plugs to name a few.

a properly running duramax will have no problems starting up cold without any smoke or rough idle.

And with that being said ... even a little puff and then should be clear as day .... if its pumped up .. a lil haze it to be expected @ low temps .... but should go away real soon :c:

Well you ever figure out the issue????????

So I am new to the diesel world and I have a 2013 LML and when I start my truck white smoke comes out the exhaust. When it is warm light blue smoke sometimes puffs out but then it stops when driving down the road.