Today I started my truck (in heated garage) drove a few blocks and when I parked my truck was idleing very rough even shaking the truck (audibly sounded like a missfire) not rythmic like the normal cold diesel lope. No smoke or anything. I left it idle and came back a few minutes later and it was running normal. Driving home it would give me a puff of black when I would step on it only. No smoke at idle or driving only when I punch it a bit. Idle was still smooth now.

couple things I'm thinking...could it be the wire to the AC comp shorting? Could it be that it was -5c (30f) could "summer diesel" cause this?

From all the reading I've done it doesn't seem like a bad injector but something goofy for sure!

 

Holy smokes!....No one knows or has any ideas? Guess that means I've discovered something new...

 

There is programming on those trucks that kills cylinders intermittently at idle during cold weather, trying to keep the engine warm. It sounds like this is what you may have been experiencing. Next time it does this, just touch the brake pedal and see if it instantly reverts to a normal smooth idle.

On edit: I just noticed your truck has quite a few miles on it. If you've owned it for most or all of those miles and it's never done this before in cold weather, I'm probably totally wrong.

 

No thats not it...this was different. And maybe unrelated to the smoke. It hasn't had the rough idle since??? I am a little concerned about the smoke though. No loss in power. Certainly no loss in fuel mileage. Couple things I'll check on the weekend when I'm not working-Clean my air filter, change fuel filter, check/clean map sensor. I have a K&N with a prefilter, thinking maybe some filter oil is on the sensor just beyond the filter...Hopefully it's something simple. It just doesn't seem characteristic of a bad injector. Any other thoughts?