I am getting very poor fuel milage and looking for input. While pulling a 20ft enclosed trailer at average speed of 60mph w/o cruise I can only get 9.5mpg. The only mods are a 5" exhaust from turbo to tail, K&N Cold Air, and Mileage Max Chip. I have since disconnected the Mileage Max to see if that improves anything. So far no improvment with the gpm. W/o the trailer I can get around 14mpg. The funny thing is when I am towing the computer shows 14.5 and when empty it shows 27mpg. I know they are typically 2-3 mpg off but wow...

I also notice when you accelerate (sit and rev the engine in park) the throttle has a slow response in returning to idle. That does not seem normal.

Any ideas would be great. I have already changed the fuel filter.

I should include it is a 2006 Ram w/5.9L diesel, quad cab, 4x4, short box, OEM tires, no bug shields, no cab visor, and 125,000 miles.
Thanks

 

I'll move this to the Diesel section where you may get better answers.

 

do you have any white smoke? excessive black smoke? poor turbo lag?
gotta know more about it

 

With regards to you revning it and the RPM'S taking there time to come back down this sounds like your injectors. I had the same issue with my truck. Apparently they spray fuel 3 times per injection cycle of fuel, and they have a tendency to stick and stay open when the gas pedel is released thus allowing fuel through which would give you your hesitation with thr RPM,S coming down. If its not too bad you may get away with taking your fuel filter out, draining all the fuel out of the filter housing, thoughroly cleaning it, poor straight additive in to where the filter sits, replace the fuel filter with a high quality low micron filter and run your truck. You will at the very least see an improvement but may not cure your problem.
My two cents worth. Worst case scenario you may have to replace the injectors.

 

there does seem to be some additional smoke. black. but not too bad. espically when i removed the mileage max. but i do expect to see alot of black smoke when mashing on the throttle.

 

OMG!!! i checked pricing on injectors themselves and wow. is there a way to test and see which one could be causing the problem or do they all have to be replaced? thats just 5k in injectors. Is that something I can do? I am somewhat mechanically inclined...

 

Sorry for the late reply i went away for the long weekend, oh and my newer 2006 dodge truck broke down, and i just tested it and number 3 injector has gon bad.
Anyways the best way to test your injectors is this, take your valve cover of(6 x 10mm bolts) unplug the wiring harness to the injectors, there are two of them, the front one is bank A and the one to the rear is bank B. These are located on the right side of the Head. Get a quality automotive tester and set it to measure in Ohms (resistence), now test each one of your injectors by placing your automotive tester wires on both terminals of the injector solonoid. You shoul be reading 0.3 ohms is very good, anything above 1.0 ohms is not good. ideally they should all read the same. My bad injector reads 4.5 ohms so ime of to spend a large sum of money to replace it.
As for doing it yourself only you know your skill level, the back injector furthest away from you is a complete pig if you got big hands like me.
hope this helps you and please let me know how you get on with this problem.

 

Little update. Took into Dodge for diagnostic, they found NOTHING!! Big Surprise there. They found no codes for the low fuel mileage or with the slow throttle response. Could it be the throttle itself? The reason I ask is the dash gets it reading for fuel milage for the throttle pedal and that is so far off it has something to do with the throttle pedal. I see that cost just under 400 and if that dont work wont be able to return it.

A buddy said he changed out a bad transmission and he went from 9 to 14mpg granted thats on an old chev blazer.

I have written a post about a shutter in the transmission when accelerating from a stop in forward and reverse, and of course the transmission shop found nothing when diagnosing that. They even changed the valve that increased pressure but that did not make any difference. He basically said unless they tear it apart they wont know what it is until it breaks down.

Still cant believe this thing only get 9.5mpg while towing the trailer.

I have not tried ppc25's trouble shooting yet but it looks like i may have to.

Thanks to all, any other ideas let me know.

 

as far as the rpm's being slow to drop during a free rev, that is normal for 03 and newer engines, they all do that, but something does seem to be a little off with the milage, what it is, i'm not to sure but you should be ruffly around 18 mpg's with no load

 

I believe I am in the ball park when empty. Maybe around 15 or so? I bought the truck used w/125000 miles.