stuttering/rough idle - frustrated
My 2006 6.0L w/78K miles has lately been plagued with an intermittent rough idle situation. The problems I am experiencing are rough idle, stuttering off-idle, very limited power and extended upshifts.
I can't seem to put my finger on the triggers, but I would swear it was temperature related. I know it sounds silly, but it's really the only thing that has changed. Overnight temps were in the 60's last week, and that's when I started having problems.
I seemed to notice the problem after driving short distances, stopping and then starting again, before the engine fully warmed up.
After more "intense" driving (highway) the problem seems to go away.
One other thing I should mention - the last tank of fuel was 100% biodiesel. The idling problem seemed to be the absolute worst when I was very low on fuel (Saturday). In fact, the low fuel light was on. I filled the tank up (diesel), and still had the idling issue. After a quick bolt down the highway, no more rough running.
Now, I'm no stranger to fueling issues with biodiesel. If my problem weren't so intermittent, I would suspect fuel filters. However, they were both replaced at the beginning on this month.
Over the weekend, temps warmed up (90's yesterday), and this morning, I did not notice anything except a slight rough idle.
I was planning to get the truck into the shop today, but I held off because I didn't want to waste time with a "cannot reproduce" situation.
History: this truck received a new turbo last month. I towed a 4000lb trailer about 3000 miles earlier this month. Performed flawlessly, but toward the end of the trip, I noticed a faint coolant smell. I have since replaced the coolant reservoir cap and haven't really noticed it. Coolant level is at MIN, and I have not tried to find traces of dried coolant anywhere.
Also, I have been running custom SCT tunes from Innovative Diesel. I was running the street tune, which I removed on Friday. This did not seem to make a difference, nor did applying the tune (weeks ago) coincide with the problems appearing.
Thanks in advance for any tips.