2006 Excess Smoke, rough, low-ish mpg

[Red Rocket]

Hey everyone, I have some issues to get your input on. I've had large-ish amounts of smoke, since the truck was new. I've also battled a rough idle, not too bad, just enough to make you think. Now with high fuel prices, I'm worried that I could be doing something to improve these couple things, and I'd save at the pump. Realistically, I never get much more than 15 or so on the HWY, less in town. I burn a WHOLE tank in less than 400 miles. Seems like it's slowly gotten worse.



The only thing I constantly hear about are injectors. I ran it up to 1500 and took some temps at the exhaust manifold off each cylinder. 4 of 6 were 175 and two of them were only 150, and I checked them all more than once, so it was consistent, and it was cylinder 2 and 5.



What should be my first course of action, should I send the oil off to be sampled? Should I replace those two injectors. Truck has 90,000 on it, would the dealer warranty this? Any ideas are appreciated.



Nick

 

[MChrist]

If it's bone stock, is there still some warranty on it? Your mileage seems low, even with your 4. 10s. I have 3. 73s and on one of my worst tanks this winter, I still got 416 miles on 32. 8 gallons. I routinely get 450-550 per tank, and I rarely get on the highway, and rarely even get into OD.
If still under warranty, I would get it checked out by dealer. Something ain't right!!

 

[Scooby]

Your user name suggests you may drive with a heavy foot!



If your mileage has been changing, however, then something is going on. You've checked fuel filters, etc... , correct?



My 06 will do 19-20 on the highway and 15-16 in city driving it easy. I'll drop to 17-18 on hwy if I consistently use the right pedal more aggressively.

 

[Red Rocket]

Yes, I know what my name suggests... That was ten years ago. I am not expecting to see a 19-20 tank, I don't do enough highway for that, but I just feel I'm off by 1 or 2... . I've owned three cummins trucks, and I'm getting lower than either of them got. I guess I'll call the dealer and see about getting it in for warranty on injectors or whatever that may be.

Is there any validity to my temp probe test for cylinder temps?

I've got about 8,000 on the fuel filter, I change that pretty regular. Truck still runs good, just not as nice as others I ride in like my brother's 05. His is smoother, quieter, and he gets crazy mileage.

 

[Scooby]

I was just giving you a hard time about your user name.



I feel the same way about my 06- its not as smooth or quiet as my 04. 5 was. I also "feel" like there is more restriction in my truck - like something is holding it back a bit.



My 04. 5 was a dually with the NV5600 transmission and the best I ever got empty on the hwy was 17. 5

 

[MChrist]

Regarding your temps, I've done that once before, and they seem to fluctuate about 20 degrees. I'll do it again today if I remember, and post my temps for you.
I don't know if injector cleaner works for these trucks, but have you tried that?

 

[MChrist]

I took 2 readings and here are the averages:
#1 200
#2 215
#3 240
#4 240
#5 200
#6 195
These make sense, since outer cylinders don't share heat with adjacent cylinders.

 

[DClark]

Are you guys looking at the computer mpg or are you calculating it? My '05 shows 20+ on the trip computer but actual is more like 15 mpg.

 

[MChrist]

Hopefully, everybody on this website knows that they should not trust the overhead "lie-o-meter". I hand calculate every tank. I even use the same pump unless I'm out of the area and I can't fill up at home.

 

[Red Rocket]

Yeah, my mileage numbers are third in line of concern, and I rarely even look at the overhead meter. The engine on occasion stumbles and shakes, but overall it's not near as smooth as my brother in law's 05. It also smokes like a freight train. Tomorrow, I'll take a video clip of the smoke, you guys can tell me if it's close to normal.

 

[MChrist]

"Bone stock, stumbles, shakes, and smokes like a freight train"??? Something's wrong, my friend. .

 

[cerberusiam]

"Bone stock, stumbles, shakes, and smokes like a freight train"???

Injectors, injectors, injectors. Sad to say but thats the normal problem. :{



Rather than a temp test on the cylinders, its not very accurate, get a shop or dealer to run a cylinder contribution test. That will tell you way more than any heat gun test.



It is quite likely 1 or 2 injectors causing the issue and you should be able to see that on contribution test.

 

[CDonaldson]

The first two years of owning my truck (bought it new) I had a little haze/black smoke and slightly rough idle in the winter with my 2006. I used an injector cleaner and that seemed to straighten out both problems both winters. Then I installed a 2-mic fuel filter between the canister and the cp3. I have not had the problem since. Keeping the air filter clean is important also, when it's dirty, it will cause smoke too.



I still got a little haze on winter fuel after the 2-mic fuel filter, but I added a lubricant to the fuel and the haze went away. Since the ULSD fuel came about just before the winter of 2006, I cannot say whether it all might have been caused by the ULSD. I did have a little haze on the LSD fuel, we were still using it when I bought my truck.





CD