4 mpg drop??

[DocDetonancour]

Friends 03 48RE has suddenly dropped from 19 to 15. New air filter didn't help. He thinks the valves may need adjusting. What do you guys think, seems like a strange thing @ 22k miles. thanks, Doc

 

[Summit]

That's odd for me, i went from 14-17 when i broke 20k mi.

i'll break 25k fri. . a. m. going to I. F. in the a. m. .

i'll let your friend take my truck for a spin to see if there's any diff.

where's the mpg drop? I-15 speed or in town? let me know.

 

[jray]

The air filter would difinitely be the first place to begin. If that didn't help I'd try some stadyne fuel additive. I have seen my mileage drop also. After cleaning my re-usable air-filter I saw my mileage improve. I also noticed that my mileage improved after running injector cleaner for a few tanks.



Something that I've noticed with respect to the overhead MPG gauge is that it's rarely accurate. I've found it to be either high or low and off as much as 2 MPG for my truck. I find that it tends to be a little more accurate when you reset all the resettable items in the overhead console ( I. E. MPG, Distance Travelled, and Time Travelled). If he's depending solely on the overhead tell him to check the mileage by hand. Also if he's resetting the overhead MPG make sure he's resetting it all.





2003 SLT 3500 CC/SWB 4X4 305/555 48RE LIMITED SLIP

 

[CChase]

Bad fuel maybe? I'd change fuel filter and go to a high volume fuel station and see if the mileage comes up. Did he tow anything. Mine I have noticed if I tow, it will seriously throw off the overhead computer. Towing 8k for 20 miles drags my mileage down to the 16s for the remainder of the tank, hwoever hand calcs show it at 19 or so... .

 

[posey-smoker]

I have also noticed a significant drop in fuel mileage. I have lost 3 mpg over the past 3 tanks of fuel. Here are my issues:



Loss in mileage, knocking sound from under the engine only at the last piston, noticable loss in power, hard to start after the engine is warm with white smoke and I have a fuel leak that looks like it's at the furtherst back injector.



3 months ago I hade the fuel pump replaced due to a crack in it.



I will be scheduling a trip to the dealer to look into this. Any thoughts???

 

[geusterman]

MAP sensor dirty. George

 

[R.M.THOMPSON]

DEBRI in a injector ?

 

[DocDetonancour]

Nobody thinks adjusting valves will help??? Thanks, Doc

 

[MCornwell]

Valves...

At 22,000 the truck should NOT need the valves adjusted...



Check all of the boost connections



-Mitch

 

[Vaughn MacKenzie]

I checked my valve adjustment around 20k and it was pretty darn close. I tweaked 'em up to . 008" intake & . 018" exhaust while I was under there.



My '03 was a lot closer than the valves on my '01 was at 50k or whatever it was when I checked them, and other Rams I have seen with valves getting close to being out of spec with less than 100k on them.



Cummins has a very wide tolerance spec for valves, way too wide IMO for guys who want a fine-tuned and top-performing machine



Vaughn

 

[keimmmo]

Still a fairly new truck. Have you recently added any accessories that could affect the aerodinamics? I have seen a bug deflector alone cost 2mpg.



Steve

 

[Jeremiah]

Calculated?

S'cuse me, but nobody has mentioned whether your low mpgs are calculated or taken from the overhead computer. Forget the overhead and go with calculations!