I'm with you drivvven on the instant mileage. I don't think its not there because its not possible but because they don't want us to see what these trucks are able to do. If you went to a lot to by new trucks and were able to see which one got good instant mileage which one would you by? And which ones would set on the lot and never get bought by a informed person anyway? I haven't heard of another make of model of any other vehicle that seems to have such a wide difference in off the show room variance.
They make a aftermarket gauge called tha scan gauge, (scangauge.com) that some owners have used and claim it worked well. I am going get one soon to see what my guessing gauge (overhead ave. thats off +/- 1-4mpg) has not been able to tell me.

 

I'd be surprised if it worked like you think it will...Same as the factory, Dont have the right componenets to do the calculation

 

Herrin821, Thanks for your reply. What you say seems to make sense to me, but,.....

Well,... I'm not saying that your wrong about this, because you sure do sound like you know how they calculate ECO in the gasoline burners, but how then do they calculate AVG ECO in our diesels, and why couldn't they use the same algorithm but with a much smaller divisor in the equation?

We have all done “hand calculated” fuel economy problems, couldn’t they do the same thing just use the last 1/10 mile traveled versus one tank range (350-450 miles).

I know that academically it may not be as perfect an algorithm as one that uses the mass airflow in the equation, but it sure would be better than what is there now,... nothing.

I would love to hear more about this before I can rest this subject in my mind.

JZ


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I'm trying to find where I've read this...I asked the same question before, and found alot of info....


What it boiled down to was the individual engine components report to the ECM,and the ECM uses these values to make economy estimates...Then the ECM reports certain values to the EOM (electronic overhead module) to display instant and average economy....It's all ODBII based....That how the ScanGage works, or doesnt....Not all vehicle report the needed values to do the calculation.....So if ScanGage cant get the needed values from OBDII, it cant figure economy....

The basic problem, like I said before, was components, specifically Mass Air Flow.....Vehicle speed vs. rate of fuel consumption (mph vs. gph) gives you a rough estimate.....Add in mass air flow, and you can determine engine load (idle coasting vs. WOT)

With a Hemi:
Mass air flow
Throttle postion
fuel consumption
vehicle speed
Engine RPM

With a Cummins:
Manifold Absolute Pressure
APPS position
fuel consumption
vehicle speed
Engine RPM

So it all boils down to what diagnostic components are availble to report values, then what the ecm does with that data....


If I can find the stuff I looked at before, I'll post it




I know exactly what you mean about this...My '02 gasser, was best at 67-72 MPH.....I got to the point I could tell my best cruising spot by the sound of the engine....But the best I ever got with that truck was 15 highway Hope to find it with this one

 

I did a search for the scan gauge, didn't find it, but 2nd gen 24v trucks had it from what they were saying. If they had it why not now?

 

It all depends on what it can extract from the OBDII....I dont have one, so I cant say for sure....Try it and see....Its only money

 

...because it's a worthless.

 

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February 6, 2006

Subject: So It Can Be Done!


Here is just one more tidbit of info, about our instant mpg discussion.

In my 2005 Cummins Turbo Diesel (CTD) Owners Manual, page 121, Distance To Empty paragraph, it states, “[DTE] Shows the estimated distance that can be traveled with the fuel remaining in the tank. The estimated distance is determined by a weighted average of the instantaneous and average fuel economy, according to the current fuel tank level.”

So,... it would appear that our Dodge diesel does have the ability to calculate “instantaneous” mpg! Again, I ask, why can’t we display it on the overhead console?

Hey Dodge,... "ya got your ears on good buddy?"

JZ






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Just Hit The Reset Button While Moving...it Will Reset Fuel Mileage And Give You An Instant Readout....

 

That's correct on 03-04.5, but not on the 05-06's. The 05-06's default to the previous avg, then move up or down from there, so you can't get an instant readout like you are getting.

 

my 05 gives me my instant when I push the reset. Maybe you could get the computer to "hold" the reset button when you are in the mpg screen. I too agree that if you say it can't get instant mpg then why can it give us avg mpg??? Obviously the computing is there to give avg. why not shorten the avg mpg to about 1 mile or so. I think that would give me a closer example of my mpg than reseting mine all the time......

On another point if I can't get mine to do instant then How can I get my avg to be correct?? Mine is off normally about 3-5mpg to the high side. Even if I couldn't get accurate instant mpg. I would be able to tell where my best mileage is. I could be off 10mpg for all I care as long as I would know 26 is better than 19. I would shoot for the highest I could get regardless of what the actual number is.

 

I was at the dealership and they couldnt figure it out but if you do hold it down and press it twice in two seconds it does reset it and I did it on my 06.

 

__________________________________________________ _____________
February 7, 2006

Very well put Underwoodtransp! That's what I've been saying. If it can do one calculation then it could use the same algorithm with a shorter mileage divisor and create a “Simulated Instant ECO" output.

Another thing that I have noticed with this string's subject is that; those that like this idea of "Instant ECO” really want it, and those that don't like the idea, think it's not worth the time. I would argue that the same thing could be said about why we have two odometers. One that is not resetable and the other called a "Trip Odometer", in fact many vehicles that have "Trip odometers" have two, "Trip A" and "Trip B"! A lesson we learned from the imports.

But either way there seems to be a strong interest, and it seems to appeal to a good number of us that drive diesels. Many of us drive diesels because we want to and less because we need to. I call that passion.

I love my Dodge diesel for many reasons, one of which is the idea that I can drive this 7300 pound brute AND still get about 20 mpg! The way I look at it, the fewer gallons I have to buy, equalls "Less Ammo for Allah", and that is a good thing. My old Ford Taurus that weighed less than half, burned gasoline, and inspired no passion, got 23 mpg. I'm sure it would get even less if I loaded it down with 2 cords of firewood . My Dodge Ram doesn't even bend a leaf spring with 2 cords behind it.

I would think that Dodge would want to tap into this passion and do what it takes to cultivate and grow it. Adding simple and inexpensive functions to the vehicle, such as "Instant ECO", has a huge ROI (Return On Investment) to Dodge, inspires passion towards our trucks, and adds value to both sides of the equation.

Most of us would agree that we are tinkerers at heart and we like gauges, gadgets, & gizmos. I think that Dodge missed a very easy base-hit by deleting this simple function from the Overhead Console.

Now back to my original posting. How do we fix it so that those that want it, can get it to display "Instant ECO"? Or even "Near Instant ECO", would be appreciated.


JZ




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Well I'm going to find out if these www.scangauge.com things work or not. I orderd one today. They do have a thirty day money back garante. I've got other vehicles to use it on anyway.

 

I see absolutely no reason why an input from a mass airflow sensor would be needed for a fuel mileage calculation. That's greatly overcomplicating things.

The computer needs to know two things to calculate mileage, either average or instantaneous. Those things are: 1) Vehicle speed 2) Amount of fuel being injected

Those two things are easily available-the vehicle speed sensor(s) supplies one, and the other is probably already calculated. The computer knows rail pressure (there's already a sensor for that), and it knows injector pulsewidth. The rest is irrelevant.

The previous year trucks already can display instantaneous mileage. It's not convenient, but hitting the reset button does just that. That proves the instantaneous mileage is already being calculated. It should just be a matter of some reprogramming to display it, updated once or twice a second.