Its gonna be off either way, I think they all are.

 

:ditto:Mine reads 17 mpg but when done by hand 13 mpg a round town.

 

They read in US Gal..............SRXtreme

 

light throttle driving seems to confuse it more than when your working it hard

 

Interesting thought. If the overhead were using Imperial gallons and not US gallons in it's computations, it would certainly be off. (Pause while I go to my handy units converter.) Yup. If I convert the MPG my overhead is reading, it comes out remarkably close to what my hand-calculated MPG has been. Could the lie-o-meter problem be this simple?????

 

Mine reads 22.5 highway and hand calcs 18.5

 

I know its not right, I usually calculate better then the console. But I use 4.54L per gallon...

 

Mine says 21.8 and hand cal. I get 15. That center console MPG thing is pointless they should have just left them out of the trucks when they built them. How are ya'll hand calculating?? what is your method?

 

How are ya'll hand calculating?? what is your method?

Record the number of miles between fillups. Miles divided by gallons. From my fillup last night:

489 miles
25.2 gallons

489 miles / 25.2 gallons = 19.4 miles/gallon

The lie-o-meter was reading 22.7 MPG, which comes out to 18.9 MPG if it was calculating based on an Imperial gallon and not a US gallon. Still not an exact match to the actual mileage, but a whole lot closer than the number displayed by the lie-o-meter.....

 

I managed to bury my lie-O-meter on a recent road trip.

 

:confused013:My 06 was imported to Canada from West Virginia. It reads Us Gallons and liters per 100 kilometers. Now tell me that doesn't throw a wrench in to the calculations.

 

Ummmmmmmmmmm Thats how they all read..............SRXtreme

 

Does anyone know of a built-in, hidden diagnostics mode in the overhead console? You know, hold down one or more buttons while turning the key on, get into the secret factory test menu. Just wondering.....

 

Test mode for what? If you want to check for codes turn ignition key on/off 3 times and codes will display at odometer. I am not too sure how new of a vehicle this still works on but it works on my '03.................SRXtreme

 

This still works for retrieving codes.

A lot of electronic components come with "hidden" factory tests in them, if you know how to activate them. It usually involves turning on the power with one or more specific buttons being held down. The reason why they do this is so that the installers on the assembly line can verify that all of the display segments are working, check sensor readings, etc without the engine running.

Some instrument clusters in other brand cars will go into test mode if you hold down the odometer reset and turn the key on. Once in test mode, you can cycle between different tests (all LED segments on, all analog gauge needles at 1/2 reading, instantaneous sensor readings, etc.) The factory radio in my Audi will even display a hexadecimal signal strength meter for whatever radio station you've got tuned in while in diagnostic mode.

Anyway, I was just wondering if anyone knew the secret button sequence to trigger this in the 2006 overhead display.....

 

I think he means to calibrate the overhead MPG display

 

Ok. Now that I finally got my truck running properly I checked the mileage... The overhead console was right on. I did the calculations using imperial gallons (4.54L). I think now that our lie machine is calculated in imperial gallons...

 

Sorry, it may work out that way for the US mpg option but that just shows you that your overhead is off by 20%. Hence, the nick-name ... "lie-o-meter". The options you have are US and Metric ... there is no UK or Imperial gal. option.
All you have to do to determine which ratio the overhead is using (3.78 US or 4.54 Imp.) is to compare the end result to the L/100km figure ... correct?
We know 100kms = 62 miles.
hollingass has shown you the way.

Here's my actual O/H readings as an example. It is now reading:

16.6 mpg and 14.2 L/100 kms

Using 3.78 US ... Divide 14.2 by 3.78 = 3.76
which means 3.76 US gals per 62 miles = 16.5 mpg

Using 4.54 Imp. ... Divide 14.2 by 4.54 = 3.13
which meaans 3.13 Imp. gals per 62 miles = 19.8 mpg

So, the US option on the O/H means just that ... 3.78 US gals per Litre. Your O/H is telling you that you're getting 20% better mileage than you actually are. Mine is all over the place depending how the truck is being driven ... it's useless to me. Hand-calculating is the only method we can take seriously ... period.
Go out and grab the 2 readings (US & Metric) on your O/H and convert then compare them like shown above and you will see. They must equal one another

 

if the lie o meter was accurate, you could convert the indicated reading mp(us gallon) simply by adding 20% or multiplying the reading by 1.2
or the metric conversion by dividing the reading by 4.54, then dividng 62 by that number ie: 10L per 100km = 100km = 62 miles, 62/(10/4.54) , 62/2.2 = 28mpg cdn

 

wow... you have no idea how much my head hurts trying to understand those calculations

 

Same here haha, But that was the canadian MPG reading

 

thanks for clearing up what i was trying to say. as a Canadian ive always hand calc my mpg on a 4.54L gallon, but since the lie-o-meter is USgallons i am actually getting 20% better than indicated, thats if it was accurate. hand caulculating is still the only reliable way. the meter can be used to determine optimum cruise speed etc. as a side note, i think any pressure box's will throw the meter off even more, when i had my edge EZ on i could get a indicated 9.2L per 100km which would be 30.7mpg cdn. I wish!!
its been a while since i did a good hand calc, last rough estimate i did was filling up in Calmar AB driving through Edmonton and to regina. 800km, filled up in Regina put in exactly 90liters, hand calc'd to 25.25mpg cdn, and my meter said 27.1mpg US. so my edge EZ through it off enough to flip the us/cdn error around. not sure if my Smarty throws it off

 

If the lie-O-meter reads 20% less then actual then why did it calculate dead on?

 

I use my gps to caclulate miles/kms, driven, most ppl have changed their tires sizes which throws out any milage calculations, even with stock tire sizes factory odometers have been known to be out.

 

So how does the overhead MPG gauge work? Does it use the the fuel gauge and odometer? Does tank profile play a major role (From full the 1/2 mark takes more time than 1/2 tank to empty) in calculating the MPG? It really sucks when you read 20 and hand caculated gets you only 16.5 MPG. Looks good when I show off my gauge to gassers... LOL - I guess it really has a purpose... LOL

 

hey bobser, it is a coincidence. Sorry I can't think of a better, more clear way to explain it than above . The next time you do a hand-calc. of your mileage, compare you L/100 km numbers to your US mpg ... that should clear it up. They MUST convert to the same # as I have shown above. Otherwise your truck would be obtaining 2 different fuel economy rates at the same time ... which is impossible ... correct? :thumbsup:
FYI, I did up an Excel spreadsheet to track my fuel usage, economy, costs, etc and have verified every tank of fuel since new off the lot. It is US gals.
Please let us know what you come up with.
later

 

some people say it's close....others not so much....mine have all been pretty close to hand calculated...maybe I get lucky

 

back when i drove a hemi i had asked the question of how it calculates the mpg, i was told by somebody at DTW and by a mopar mech that the computer actually counts the injector cycles, and with the known fuel pressure and known duration of the cycles it could accuratly measure the fuel consumption. i know with my truck anyways, if i put my edge EZ in on its highest level my indicated mpg will jump up 3 or 4.