Where has MPG gone?

[DGamelin]

My 04. 5 has been losing mpg for awhile now. The loads that I used to hall at 8. 5 to 9 witch I thought was just ok is now down to 5. 5 to 6. It aggravating when I find myself happy with 6. 5. The truck has had plenty of issues but never nothing with the engine. It has had a SJ in and out of it a few times. The empty mpg is good somewhere around 18 it has had a couple of runs that hit 21 with no front drive shaft. It is hard to figure the mpg because it cares a 100 gallons of fuel so it is loaded half of the time.



I am on the fence about buying a 2010 I like the gearing of the new autos and 4. 10 but not the price, and would hope my loaded mpg would be better. My 04 only has a 100k on it. I usually keep them to 250k. I was about to order a set of manual hubs for it when a customer came in with a 2010 so I got a good look at one and it being the last year before the urea is nice.





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93 250 2wd xc 354 auto 274k

04. 5 3500 4wd qc dully 373 6speed 100k

 

[EricBu12]

Could be the injectors are getting a little dirty. . maybe run some cleaner through it... change the FF and stuff like that. Clean the air filter. . (or replace if stock). .

My 2009 is doing pretty good. Getting a little more broke in. . I tow a heavy 5th and it goes now around 8-9 towing... . Around 16 mix city and hwy empty... . If I baby it on the freeway, it can get up to 19 all freeway empty... The 6 speed Auto takes some getting used to but all in all it is not bad. . the built in Jake works wonderful... I am going to add a set of airbags to my rear suspension mainly so the headlights don't point to the signboards.

 

[rscurtis]

Urea will be your friend when it gets here. I also think Cummins should go the was of the Duramax and go to the extra injector for regeneration instead of dosing the cylinders.

 

[BrianJ]

... when a customer came in with a 2010 so I got a good look at one and it being the last year before the urea is nice.

According to the Dodge and Cummins engineers that participated in the Dodge/Cummins Q&A session earlier this year only the C&C's are getting urea treatment, and it is not on the radar for the regular pick-em-ups anytime soon. Not debating the pro's vs con's here, just clarrifying that Urea is not coming anytime soon unless you are in the market for a C&C.

 

[Crunch]

Urea will be your friend when it gets here.

I wonder if that means buying a diesel will get you put on a terrorist watch list... :-laf Maybe the urea tank will have a seal on it that lands you in prison if it is broken by anyone other than a certified federal yahoo.

 

[JBallou]

Only if you are in California, they will tax it and add it to the referee station.

 

[DGamelin]

BrainJ



I didn't see that. I will look for it. I don't need a third tank to fill.

 

[J.BURCHFIELD]

The EPA is mandating lower and lower sulfur content in the diesel fuel. I have noticed the difference in my Ram. As long as we have the EPA we will have problems of one kind or another. Typical inefficient government agency full of corruption. I don't know which is worse the ACLU the IRS or the EPA. They all need to be abolished.

 

[HBarlow]

I agree with the criticism of the federal tree hugger agencies but . . .

returning to the original question, do you have gauges? Gauges help with diagnosis. Will it still develop full boost under full throttle loaded acceleration or grade climbing? Does it smoke?

I'm sure you have changed air and fuel filters to eliminate those causes.

If you know a Dodge dealer with a Level IV trained and certified Cummins diesel tech and sometimes just a good and experienced one who reads and learns, the service department can run an engine diagnostic test for about $100 - $150. The test can identify developing problems. Components like MAP Sensor, and . . . can't think of the name of the other sensor, there are two sensors on Cummins diesels that are important. A failing turbo could also be a problem.

I don't speak the language but I'm guessing the abbreviation "SJ" means Smarty Jr. or other black box? I've never used one and know very little about them but problems could be related to use of a box.

I would consider first the filters, second the two sensors, and third the injectors. Several years ago when my high mileage '06 had a minor problem (turned out to be an FCA) I inquired. A Cummins dealer told me a six pack of Cummins reman injectors sold for $1700. Expensive but a lot cheaper than a new truck.

On Edit: I think you posted this in the wrong forum. Probably should have been in the 5. 9 engine forum where it would get greater visibility.

 

[J.BURCHFIELD]

I have the old 12v and EGT is the only gauge I have. I drove an 18 wheeler from 1966 to 1982. 10 of those years was owning my own truck. Dividing gallons used into miles traveled has always told me all I need to know. I have the good old mechanical Injector Pump and get it calibrated more often than recommended. I only tow 6,000 pounds when I tow. It does not slow down on the N. Carolina or Tenn hills so it is good enough for me. It is when you are going up a hill below the speed limit that you become a road hazzard. I have not gone for any of the gadgets that give more power. Stock is good enough for me. These are not the answers you were looking for but all I know to tell you.

 

[everittak]

I found that my 06 is very sensitive to my air filter getting dirty. Even with my 'filter-minder' reading in the green still, the mileage drops pretty fast when the filter starts to fill up. I'd change the air filter, and run a bottle or two of power service through her and see where you're at...

 

[DGamelin]

Just got back from another run on the way down I got 19. 3 at 68mph very happy. Picked up a new gooseneck had a killer load meaning not to high balanced well, about 15400lbs w/o truck and a little more arrowdynamic. Truck ran away with it no sweat at 68mph then at about 200 miles the new trailer blew a tire. It was 97 degrees outside, so it ****** me off I was changing a tire on a brand new trailer. The other tires were running so hot I drove the rest of the 1250 miles at 60mph. So my mileage was decent about 8. 5, so go figure. The only gauge I have is a exhaust temp and all of the filters had just been changed recently. I don't have the smarty in it anymore. The truck runs great, just the mileage isn't consistent then again nether are my loads. But even with the worst of loads I dont like seeing 6mpg. Wouldn't you think the engine would run a little ruff if it needed injectors?



Yes it should have been in the 5. 9 engine



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93 250 2wd xc 354 auto 275k

04. 5 3500 4wd qc dully 373 6speed 103k

 

[MAshley]

Tire blew and the rest were HOT. WOW I assume you weren't overloaded for a GN trailer. . was the tire Preasure high enough ... What brand of trailer is this, tires, Really shocked over the tires blowing and the rest being really hot.

 

[DGamelin]

I just got back with another load. The load that blew a tire wasn't overloaded and tire pressure was good, a Freestar Radial S/T 235-80R16 E-Range. The side walls looked soft to begin with, to much flex makes heat. I was actually a little lighter than normal for this size trailer, but this brand of trailer moves their axels 12" further forward on this model, so the trailer axels carry more than the trailer I would normally use. It was 97 degrees outside with a 115 heat index. The front right is what blew on the first trailer. Something I noticed on this trailer I just brought back (a cattle trailer), the front right tire ran hotter than all the rest again, and the right rear was warmer than the two left tires. I believe after checking this again and again, the right front tire is being affected by the exhaust heat. This is probably only a problem when the outside tempature is extremely hot to begin with. This load was a 24' gooseneck cattle trailer, with a dump trailer behind it and two tractors inside of it. If I could figure out how to put pictures on here I'd show you a picture of the two loads and the tire, it blew a hole large enough to put your foot in without touching any of the edges.



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93 250 2wd XC 354 auto 275k

04. 5 3500 4wd QC dully 373 6 speed 105k

 

[befrazier]

I was just wondering about the same thing on my 04. 5, 6-speed. I have a mileage max by edge on it and noticed fuel mileage dropping off by a couple of MPG. I took the edge off and noticed that my mileage has dropped off a couple MPG from what I used to get before the edge product. I will change my fuel filter, air filter and try some seafoam to clean injectors. I change the fuel and air filter when it calls for it in the book. I normally run some stanadyne through the engine but only about every 3 months. Not sure if stanadyne is good for cleaning injectors though, not sure what it does. I know if I can keep my speed down to about 63mph my fuel mileage is best, loaded or empty, but who goes 63 empty.

 

[CoastyAV8R]

I was just wondering about the same thing on my 04. 5, 6-speed. I have a mileage max by edge on it and noticed fuel mileage dropping off by a couple of MPG. I took the edge off and noticed that my mileage has dropped off a couple MPG from what I used to get before the edge product. I will change my fuel filter, air filter and try some seafoam to clean injectors. I change the fuel and air filter when it calls for it in the book. I normally run some stanadyne through the engine but only about every 3 months. Not sure if stanadyne is good for cleaning injectors though, not sure what it does. I know if I can keep my speed down to about 63mph my fuel mileage is best, loaded or empty, but who goes 63 empty.

Dont forget the ez stuff, check your tire pressure, clean filters, boost hoses are tight and simple things like that. I would steer clear of seafoam to clean your injectors as there are many other products out there specifically for diesel trucks. All vehicles get better mileage at lower speeds and you maybe surprised that you'll still get where your going at 63 mph, it just depends how much you value mpg over time. If you go 63 mph and get 20 mpg for 1 hour and then you go 73 mph and get 15 mpg, is that 12 minutes you just saved worth the additional fuel burned?



Just some food for thought, I know there are times that time is the motivating factor for your speed but when it isn't, why not slow down?

 

[RKerner]

My 04. 5 has been losing mpg for awhile now. The loads that I used to hall at 8. 5 to 9 witch I thought was just ok is now down to 5. 5 to 6. It aggravating when I find myself happy with 6. 5. The truck has had plenty of issues but never nothing with the engine. It has had a SJ in and out of it a few times. The empty mpg is good somewhere around 18 it has had a couple of runs that hit 21 with no front drive shaft. It is hard to figure the mpg because it cares a 100 gallons of fuel so it is loaded half of the time.



04. 5 3500 4wd qc dully 373 6speed 100k

How many injectors have ever been replaced in this engine? I've experienced mileage going up and down on my 04. 5 and the last time a fresh #1 injector netted me the best towing mileage I've ever gotten. This was even with reasonable highway unloaded mileage numbers. So far in 110k, I have replaced 6 injectors and places like DDP recommend getting rid of the stock ones and going with the new stainless bodied versions (of course they want to sell them but after going thru so many I'm thinking of doing it to avoid future problems). Anywho, at 15K plus, I've only got 8. 1mpg at speeds slower than 68mph.



I would still get the diagnostic done and an injector balance to at least get the basics checked.

 

[DGamelin]

All the injectors are still stock. I had a front pinion seal go out for the 4th time and had a steer tire go bad on the truck. This isn't going to be my year for tires. The engine runs so good I hate to mess with it, and finding the time. To have the injectors balanced I'd have to take them out and send them out. There's no one any where near here that can do that. We usually send injectors down state for rebuilding, and I just can't have the truck down right now.



____________________

93 250 2wd xc 354 auto

04. 5 3500 4wd qc dully 373 6speed 108k

 

[Crunch]

So far in 110k, I have replaced 6 injectors

Good grief! This is the kind of stuff that worries me when I'm out on the road. Why do you think you had 6 injectors go out with such low mileage?

 

[ktb]

run the valves recently ... when they go out milage drops off pretty fast