Usually when I start my truck, the computer near the rear view mirror tells me I'm averaging 12-12.2mpg. But this morning when I started it, it told me I am getting 11.4mpg. I restarted the computer a couple of times and even turned off and restarted my truck, and it still stayed the same, so it looks like its there to stay. Any reason why it'd change so drastically over night while sitting??

 

Temperature or humidity changes in your area of late? I don't know, I'm reaching.
WC

 

got a low tire or brake dragging?

 

hmm could be...i know that the temperatures have been the same for the last 2 weeks and it always stays in the 12's. Maybe their is a brake sticking though, there is a bit of weird noise i heard today at the atm when i was strolling slow to the atm, i could hear something from the rear axle...could be could be...but the mpg's are def. in the low 11s now...an entire gallon lowe than usual? so damn substantial....

 

Lol, talk to motorbreath about this. He has a highly efficient step-by-step trouble shooting procedure for this! Basically, drive several tanks of fuel through your truck for hundreds of miles and compare your mileage with others on this forum, then try to reason mechanically what where the deficiency is coming from!

 

[sm=pcwhack.gif]

 

You've been running that thing awefully hard, at least I'm guessing so if you drive itlike you didthru the cemetary, or if it gets driven by your brother a lot.

I can't remember if you've said that you fixed it lately, but check the plenum gasket.Then check things that can wear out due to hard running.

And lay off this:

[sm=nxsmile.gif] LOL!

 

They had nitrous balloons at a party I was at saturday night

 

=

Yea, I'm not sure about the problem. Motor ought to be able to give you some advice.

 

It is best to re-set the overhead trip computer at each fill up.

MPG is not a steady thing.
It jumps around a lot naturally,
just like bullet holes in a target.

Even if you are driving very much the same
it is 'natural' for your MPG to vary by 2 or more.

Here's some MPG's I kept careful track of
driving over the same roads with the same behavior:
=====
I have since made 3 more 300 mile long mpg tests in city driving since i
posted the original 6 tests. My test results now look like this:
-----------
OD turned off runs:

7-19-00 14.32 mpg Amoco87
7-29-00 15.17 mpg Amoco87
8-08-00 14.23 mpg Amoco87
9-08-00 13.53 mpg Amoco87
---------------------------------
average 14.31 mpg

OD turned on runs:

7-12-00 14.16 mpg Exxon87
8-17-00 14.25 mpg Amoco87
8-24-00 15.49 mpg Amoco87
9-01-00 15.03 mpg Amoco87
9-12-00 14.35 mpg Amoco87
-------------------------------
average 14.66 mpg

As you can see, so far the OD on/off difference seems to be small with a
slight 0.3 MPG edge to leaving OD on while in city driving. That is about a 2% difference.

Note also how much the MPG jumps around.
All realworld tests have 'random variation.'

The overall average of nine tankfulls is 14.5 mpg
but varies from 15.49 to 13.53,
even though the driving was over pretty much the same streets with the same gasoline.

If I had done just two tests, and had by chance gotten the low 14.16 for the
OD on, and the high 15.17 for OD off, I would have falsely concluded that OD
on really hurts in city driving.

To really find reliable MPG numbers for Rams in city driving you need to do
multiple tests.