Is this normal??(aka new guy questions)

[SBilinski]

Bought my first diesel a few months ago. I am still trying to figure out what is normal. It is a 2006 Mega cab 4x4 and has about 43k miles. The only change so far is 285 Nitto tires. I have been using it lately for my pool service truck and have been getting pretty poor mpg. I am only getting around 10-11 mpg. That is hand calculating and adding 3. 5% to the odometer for tire size difference. I drive it very easy..... slow starts, coast before stop lights, the tach rarely sees 2k. Does the multiple short trips each day(20 pools a day) account for the low mpgs? Does the 4x4 keep it down that low? I have not had a chance to do much freeway driving, but my 50/50 driving has only seen around 14. Towing my 8k toy hauler got me 10(maybe low, but a hell of a lot better than the 5-6 I got out of my 8. 1l chevy).

The other thing that I noticed is when cruising down the road, on the rare occasion that I do put my foot down, I get black smoke. Is that normal for a stock truck? I was under the impression that black smoke was lost power/unburned fuel. SHould I start to investigate? If so, where?



Thanks for the input



Scott

 

[JDiepstra]

Hi Scott. Good decision joining the TDR. Let me qualify everything I say by starting off with... In my opinion... The short trips are definately not helping you. The trucks from 2004. 5 and up do not get the greatest mileage. Emissions controls and a third injection event can be blamed for this. The general concensus around here is that 4x4 costs about 1 mpg. I am not suprised that you get some smoke if you are only getting on the go pedal once in a great while. I see the same thing with my truck. I think it is partially a soot build up that gets blasted out. Also black smoke is, as you said, essentially unburnt diesel fuel. What happens is that fuel is supplied to the engine before the turbo spools up to help burn it. Yes, it is a little wasteful, but nothing to worry about in most cases. If you would like to correct that issue you would want to get a faster spooling turbo, but still, probably not worth it just to clean up a little smoke. A lot of people will say get a Smarty jr, they claim up to a 2mpg increase. I don't know cause I don't have one.

 

[B.G. Smith]

Sounds pretty normal compared to my truck which is 06 quad cab 3500 dual rear wheels, 2 wheel drive. I also have a combo 90 gal. fuel tank/tool box in the bed. I get around 9 mpg towing a 12,000 5th wheel and trying to stay below 65 mph. I get about 14 mpg pulling a 5X10 2 wheel trailer with two 4 wheelers on it, probably 1100 pounds. Best I have ever got is around 16 empty and mine will do the black smoke trick too when you get into itquick and hard. bg

 

[MScheiper]

I would definitely invest in a Smarty Jr. IMHO, you will not regret it. Not a radical tuner, but definitely gets your attention. Been running one on my 04. 5 at level 1 with the new beta 4 software and my truck smokes less than when it is set at stock level. Turbo spols up much quicker and I have seen a 1-1. 5 mpg increase on my around town driving. Less turbo lag equals less smoke. Can't speak for highway yet, but summer is now here, so will definitely report back after a few good road trips. Welcome to TDR!

 

[Buffalo]

Any chance you could have a clogged-up air filter? Just a thought!



Joe F. (Buffalo)

 

[Motorhead]

The Smarty jr will also allow you to correct the speedo error.

 

[mberry]

Any chance you could have a clogged-up air filter? Just a thought!

Joe F. (Buffalo)

This is kind of where I was thinking too. When was the last time any maintenance was done? Also, changing everything out to a good, high quality synthetic lube (of your choice) will get you a little better MPG with longer service intervals if you choose.

I easily lose 5MPG or more when I have to run around town and do short trips. Thankfully I don't have to do that very often.

 

[Matt42]

I use an 04. 5 1 ton dually with a drop in service body to haul a service trailer. With a measured GCVW of 20,500 lb, we will get 11 mpg running at the legal speed limits. It's a 4x4 quad cab with the NV 6 speed and 4. 11 axles. Best I have ever done solo is 15 mpg, but it runs nearly fully loaded all the time. We have named the truck "Eeyore" and it's a dream to drive on the highway. Very stable and predictable, and comfortable riding even with standard seats.

 

[CurtLee]

Running around town like you do isn't going to help your mileage any. But you can't be afraid of driving the truck and short shifting isn't going to help. I bet thats the smoke problem everything gets clogged with soot and when you get on to the highway it pushes it out as smoke. Try driving it a little harder. As for mileage at one fill up don't add the 3. 5% because i have the same tire setep as you and found the speedo was slow. Just my 2 cents. Welcome to the TDR.

 

[CDonaldson]

I would change the air filter and the fuel filter. I would also consider getting a RokTeck (sp) crank sensor replacement. Many of the guys with the 2006 trucks reported bad fuel mileage and when the installed the RokTech sensor and could adjust their timing a little, their mileage went up.



My 2006 gets right around 18 mpg with mixed driving in town/open roads. It gets 14/15 pulling a 12K load. Drops to 14 pulling an 18K load.



I drive very conservatively. The larger tires served to keep my rpm's at 2K when going 65 mph. My truck will also give me some black smoke when I get on it, but the amount is minimal, more of a black haze.



When my mileage starts to drop a little like your truck from too much in-town driving, I hook up a heavy load and put some miles on it, mileage comes right back up. I have the RokTeck crank sensor and have a Smarty that I used only to adjust the ties size, not running any power programs. I am using a fuel additive-OptiLube.



If you are taking your fuel mileage off the overhead, it has a tendency to be low in it's information. The best adjustment your dealer can do toward getting it accurate for your tire size is 285 I believe, but that would get your overhead a little closer in accuracy. I got a complete ECM flash done with the latest software/firmware corrections done the first of this year and my overhead is now accurate. The Smarty put it right for the tire size. Your speedo will be running a couple miles per hour slow, and also ticking off less miles overall as you drive, and probably 1-2 mpg's low on the overhead because of your tire size.



FYI, I am located an drive in high altitudes of 7K-9K, so my mileage is not as good on a regular basis as when I am driving at altitudes of 3-5K or less, then my mileage gets a little better by 2mpg's pretty much across the board regardless of whether I am empty or towing. The truck is up and down steep grades a lot as well. Also note that my climate is hot with little humidity. Climate will affect your mileage as well. High humidity drops mpg's.



My fuel mileage was lower with the stock air box, improved by a couple mpg's when I installed the aftermarket cold air box and the Amsoil air filter.



I am running the Valvoline Premium Blue oil in the engine and Amsoil fluids in everything else, 75w140 in the diffs.



Hope all that info gives you some insight, a few changes made a difference in how my trucks performance increased.



CD

 

[SBilinski]

Thanks for all the info and insight. I now have some good ideas of what is normal and what direction I can go for improvement



scott