It only runs rough for about 3 to 4 sec. with white smoke coming out the exhuast then clears up. does anybody have any guess to why or better yet the answer to solve this. Thanks in Oregon

 

Take it to the dealer.... They are seeing alot of different things causing this. One being a dirty/stuck injector and the other actually being the valve cover gasket. As crazy as it sounds it holds the wires for the injectors. The easiest way to tell which cylinder is doing it is to take a IR temp gun and measure all the cylinders cold... Atert it and right after the rough idle stop cut it off. Measure again and the cold one is the one with the problem.

 

Dump a 16 oz. bottle of grey Power Service in the tank and run it like you stole it and preferrably with a 10k trailer on the back. That should clear it up.

 

Not usually a "fuel" problem... More of a electical problem most the time.

 

He said it clears up after startup though. A couple of things here. One is that injectors can't fix themselves and the other is an electrical problem can't fix itself either. Diesels smoke. My truck did it until the time it finally got around 30k on it. Fuel conditioner and some hard running would take care of it. If he takes it to the dealer they will tell him he isn't working the truck hard enough. Cummins are notorious for smoking. They are called rag burners in the industry for a reason. I had a small cam 290 once turned up to a 335 in an old dump truck. That thing would white smoke the entire state upon startup in the mornings. Had over 500,000 miles when I sold it. Most other of my Cummins in the big trucks white smoked at startup and some were worse then others and then some wouldn't at all. The white smoke is caused by raw fuel sitting in the cup of the top of the piston. Upon startup the unburned raw fuel causes white smoke. Most likely what's going on is fuel is being slobbered in there at shutdown or drips a couple small drops of the end of the nozzle at shutdown. No big deal but it can be early signs of an injector failure if not treated properly. Keep an eye on the smoke and your oil level and run the snot out of it a couple times with fuel conditioner and I bet it clears right up.

 

Personally, white smoke at startup is nothing to be worried about. 3 to 4 minutes is a little long but generally not a big deal. Now, if it were white smoke under acceleration, that's an entirely different matter.

 

Mine's doing the same thing...sometimes it acts like a stuck injector and knocks, raps, smokes bad. Injectors were just tested (they are Flux 1s), and were fine...that's exactly what it acted like, a hung injector. Now it just puffs smoke upon cold startup, then clears up...acts like you cold started at temps under 0*F.

I have good rail pressure, everything is normal (idle, cruise, and WOT)...

It just started this recently...

---AutoMerged DoublePost---

One other thing, this is a CR...it should not smoke at start up (other than the initial puff), it should not sit and smoke at warm temps.

Can't really compare to a 2nd gen...

 

This is normal on cold start ups. What causes is it is there is raw fuel in the cylinder after shut down. When you start it up the cylinder temps are not at opperating temp yet so its doesn't burn completely.

 

Rough running/starting is not normal operation, unless it is 10*F or less out. Since the OP originally posted in July, I doubt his temps were anywhere close to that.

I cured mine, my injector bodies were bad (weak solenoid in the mix). I have started at 0*F unassisted (only one cycle of the grid heaters) with nothing more than a single cough and puff of smoke.

IIRC, there was also a ECM flash for white smoke at startup...

 

there is a fix for this, i noticed your truck is a 2k6, there is a flash for rough starts and idles, but also a known problem with this year model is injector failure, its just now showing up and bosch is catching it, keep your eye on that also, white smoke like stated is raw fuel sitting on cylinders, this passes through to the exhaust once it reaches it burns off, causing white smoke from raw unburnt fuel particles, and yes on a cr 3-4 mins is a little lenthy, mine never smokes white at startup and even on a few mornings its been around 10-18* here lately, she fires right up, no smoke, idles up for about 15 mins then back down to normal, also when it does it after it stops smell the exhaust if it smells like raw unburnt fuel, or she gets a little white under acceleration, then its injector problems, could be a leaky injector, may also want to try and perform an injector leak down test, also check oil level, does oil smell like raw fuel? is your oil level rising, oil getting thinner? leaking injectors can cause fuel to pass to crank case causing serious damage, i would get it checked out as soon as possible to see whats wrong, if you have a friend with a smarty, does the cylinder test, you can shutdown one cylinder at a time, to see which one the culprit is...