well there really isnt much of a maintenance schedule on 13000 miles. He did three oil changes in the time he had it. They didnt another oil change before I got as part of the 100-whatever point inspection bla bla bla.

IF the MDS is not working properly, would the computer diagnostic check show it?

 

I'm not sure how the truck MDS compares to the Magnum version, but I suspect it's all pretty much the same - you should be able to hear the change with aftermarket exhaust on it - kinda like going from 'B' to 'B-flat' as my brother the musician described it.

What's your tire pressures?

Mike

 

Having the dealer reflashing the coumputer is good place to start, disconecting the battery and restting the coumputer is something you can do, remove + and - cables and wait five mim, THe coumputer will realern your driving habits.

Spark plugs ( champions ) need changing every 25,000 miles, but depending on how the past owner drove the truck, plugs may need a change and the TB cleaned out.

Fill up with the 92 octane and take your truck for good highway cruse, nothing hard, just average driving, this might help clean out the engine and than run mid grade.

Winter gas may also be in use in your area and than kills any possible MPG.

Automatics kill any chance of good mileage, perhaps the transmisson is not shifting right, or the TC is not working right, you still should be under warenty and your dealer should be working with you.

MY 06 2500 hemi reg cab 6sp manual 373 ltd slip can average 18 to 20 MPG, 1800 Rpms bang on at 60 mph, only mods I have made is true dual ex, cab high topper.

You truck should be hitting the high side of 15mpg highway.

 

Is there any way to know if the MDS is working/activated on an 07? Will the tranny drop rpm's or anything like that?

 

hook up an MDS indicator light. I did a DIY on it some time ago, should be in the FAQ section...

 

Better read your owners manual before it's too late

5.7L Hemi recommended octane is 89. There have been many cases of engine damage from running 87 octane in the Hemi from detonation.

 

Just an FYI that altitude affects detonation. Higher altitudes can use lower octane gas. Up where I live 85 is nearly equivalent to 89. I do put in a tank of 87 every third fill up or so. I'm assuming the OP is in the east though, just thought I'd bring it up. BTW, no ethenol up here.

 

My 03' 2500 w/35's and 3.92 gears gets 9.4 city and 12.6 highway, has 65K miles. I know it could use a tune up and such and it will get better.

I also notice my mpg's are different depending on where I get gas at, I always use 89oct. but I get better with ZX gas than I do at say a QT or a mobile (midwest local)

 

Sorry for the late reply.
I didn't see your post till now.
The guys on here, have pretty much covered the "cold reset" and other stuff.
All good advice my friend, to hopefully get your MPG's back where they should be.
Good luck and post up what the stealership say.
Al.

 

THanks for all the help. You guys are really good with responses. Kinda like the guys on the motocross forum ive been on for so long.

As far as 89 octane goes, I purposely asked the dealer and he said 87 is fine. I never trust what mechanics/salesmen tell me...I dunno what made this scenario different.

I have an appointment for 730am on Monday, will let you know how it goes.

Im going to do the reset today.