mileage question

[LWDUPPONG]

Now that I have the FCA problem fixed and everything is running good. I have a question about mileage. I installed new injectors( reman from Cummins) in January. As soon as I put them in I lost about 5 MPG. I was able to run at 65 unloaded and pull 25 plus average. After I was only able to get 20-21 with the same conditions. Now if I'm pulling my empty 16' flatbed i can only get about 15 where as before i was in the 20's. I talked to several places and noone has a clue why this would happen. The last shop did tell me I could "TRY" a tuner to see if I gain some mileage back. Anyone have a clue why this would happen????? i'm at a loss and I'm sure alot of you are saying 20 MPG... quit your *****in. #@$%! LOL Not *****in just want to try to get the mileage back.

 

[BILLVO]

Now that I have the FCA problem fixed and everything is running good. I have a question about mileage. I installed new injectors( reman from Cummins) in January. As soon as I put them in I lost about 5 MPG. I was able to run at 65 unloaded and pull 25 plus average. After I was only able to get 20-21 with the same conditions. Now if I'm pulling my empty 16' flatbed i can only get about 15 where as before i was in the 20's. I talked to several places and noone has a clue why this would happen. The last shop did tell me I could "TRY" a tuner to see if I gain some mileage back. Anyone have a clue why this would happen????? i'm at a loss and I'm sure alot of you are saying 20 MPG... quit your *****in. #@$%! LOL Not *****in just want to try to get the mileage back.

You answered your own question.



Should have gone aftermarket for better quality on injectors.

 

[jjdiesel]

I should put a set of those in to get UP to 20!... seriously, who loses 5 mile per gallon and does'nt have a spittin, coughing, sputterin engine to go along with it?. . got to be more to this.

 

[RWood]

Was the 25 mpg according to the over head computer?

 

[Prairie Dog]

Poorly flow matched injectors will cause this.

 

[rbattelle]

I was able to run at 65 unloaded and pull 25 plus average. After I was only able to get 20-21 with the same conditions. Now if I'm pulling my empty 16' flatbed i can only get about 15 where as before i was in the 20's.

You have all those accessories installed, and you're getting 25 mpg empty? Or rather, you were? Got a log that proves it?

Your new mileage with the new injectors is on the "lucky" side of just about right based on what everyone else reports.

I wonder if you had one dead cylinder? That might explain the amazing fuel mileage before the replacement injectors. But then, running on 5 cylinders I'd expect you to be complaining about low power.

-Ryan

 

[Prairie Dog]

25 isn't out of the question. Before ULSD I routinely got 24 (hand calc) cruising at 55.

Under those same conditions I only get 22 now.

 

[rbattelle]

25 isn't out of the question. Before ULSD I routinely got 24 (hand calc) cruising at 55.

Yeah, but that's 10mph slower. Speed is a first order effect on drag, if nothing else.



-Ryan

 

[BLNRAY]

25mpg,is that metric miles?

 

[MMeier]

25 MPG with a CR ?? Must be driven on 10-15% downgrades 100% of the time !!!

 

[JBonpua]

Check out this thread I just started on recovered MPG: https://www.turbodieselregister.com...ssion-discussions/225507-lost-mpg-solved.html

 

[rscurtis]

25 MPG is possible on a 305HP CR engine. My last two trips to LI were 23. 8 and 24. 5 MPG hand calculated. This is with a cruising speed of 65, accompanied with the usual traffic on the GWB and the Cross Bronx "expressway". For straight highway driving at 65 with no headwinds, 25 is doable. At 55 MPH, I don't think 28-30 MPG would be off the chart. Look at my updated signature, no pressure or timing boxes on this truck, just the DT and air flow enhancements. Naturally, the most expensive mods give the most benefit.

 

[AMcCormick]

I think my best tank with my last truck was some where in the 22mpg area, daily average was more in the 16-18 range. Very similiar to the above truck. 03 305/555 4x4 reg cab Dyntrac hubs, stock turbo, AFE intake and plenum, straight piped, Bully Dog Torque Dog psi box, Smarty Revo sw3 and Toyo 35 MT. Current truck is much heavier and bombed up a bit more, daily average is in the 14-16 range with lots of short trips and city driving. I do very little extended freeway trips. The next project will be the Dyntrac Hubs for this truck.

 

[RWood]

My best trip was 19 on the freeway going 70-80. My truck is heavy weighing just over 9000.

 

[LWDUPPONG]

I actually was interested in going aftermarket on the injectors but I use the truck daily for my sales routes and needed to get it on the road. I figured the Cummins injectors would be higher quality. my mistake!!



RWOOD..... I questioned the overhead comnputer and calculated it myself and it was almost right on give or take a couple tenths.



RBATTELLE... Yes... all those accessories and I got that kind of mileage. I don't have a fuel log but check it everytime I fill. I run the same routes every week give or take 50-100 miles.



I appreciate all of this input. I'll have to just accept my new mileage and do the little stuff I can to make it better. I'll be getting a tuner and see what happens. I guess if I get a few more that would be great.