Poor mileage

[Kornstad]

Just updated from 03 ram 2500 laramie quad cab w/ho 6t5.9 w/6 spd to a 05 ram 2500 quad cab laramie w/ho 6t5.9 w/automatic. My 03 got 16/17 mpg to and from work(14 miles hwy round trip) just checked my 05 and it gets 12mpg!! Needless to say i'm a little perplexed. The o5 does still have the cat in it and a k&n air filter. There are no engine mods that i'm aware of on the truck . Any suggestions what to look for!

 

[p-Bar]

How many miles on it ? Should be getting 15 or so by hand calc.

 

[Kornstad]

How many miles on it ? Should be getting 15 or so by hand calc.

The truck has 110,00 miles on it. One possibility I thought of, is that this truck has a pac-brake and I wonder if excessive use could soot up the cat?

 

[p-Bar]

Haven't heard of that happening . What about injectors? Does it have any extra fuel filtration?

 

[AnOldBiker]

Was it a private purchase or dealer lot ? I'm wondering the prior owner had a programmer on it. My '06 gets 16-17 in town and 19-20 on the highway (empty). It has the 48RE.

Also, when and what was the last time it was serviced ? Or more importantly, when were the batteries removed or replaced ? I ask this since not long a go, I needed to replace my batteries due to age. When I change batteries, I fully trickle charge them and change them out all at once. From what I've been reading, if you do what I did, it sort of clears the computers memory and when you start running the truck again, it has to relearn your driving habits for the auto trans. In the mean time your mpg's suck. My average local / highway mpg's averaged 12 mpg for a little while. But in a somewhat short time, it went up again.

Could this be the issue ?


PS: Your shoud update your signature information, your still showing the '03

 

[Kornstad]

I bought it from a private party, i'm the thrid owner. I'm not sure if it had a tuner on it! The guy i bought it from towed with it a couple times in the 30,000 miles he put on it and just drove it to and from work. He really didnt strike me to be the type of guy to mess with the truck. He really seemed pretty naive when it came to diesels. To my knowledge the batteries are the original! What happens if i disconnect the batteries for a couple hours then reconnected them? Will that fool the computer?

 

[Kornstad]

The engine oil, fuel filter and air cleaner have been serviced or change

 

[AnOldBiker]

... What happens if i disconnect the batteries for a couple hours then reconnected them? Will that fool the computer? ...

Not really. If anyone of the prior owners put a programmer on it and didn't remove it before selling, I do believe the settings will stay there. Like I said, I read, and it has happened to me, when the batteries have been removed and then replaced, the trans memory was gone and it needs to relearn your driving experiences again. MPG's should drop and in a two to three tank driving time it will relearn. If your willing to try, you can see if it will clear the memory and help your mpg's, but I don't believe it will.

Can you ask the prior owner if he remembers the prior owner he bought it from and ask them. And if they didn't, ask them for their prior owners info. It's a very long shot, but worth a shot. I've heard other have bought trucks that had tuner settings left on, but was told of the tuner manufactures name and were able to pay to get it removed.

If not, you might have to talk to the dealership and find out from them what it would cost to have it redone. I don't believe a reflash will work, but someone on here might know.

Do you have a FSM for it ?

 

[brods]

Is the mpg from the overhead lie o meter or hand calc? What size tires are on it? Is there diesel in the oil? Any boost leaks? How does the trans shift? Any brakes dragging? Ebrake cables rusted up?

You will probably get 1 to 2 mpg less than the 03. 15 city 17 highway is average for an 05.

 

[LFalconer]

My truck in sig with Turbo back exhaust and 20's gets 15.5 mpg mixed, 17 - 18 hiway, depending on speed. I have 4.10 gears, this will make a difference in mileage on the hiway.

Luke