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Dano52 · **Posted:** Wed Oct 24, 2012 7:14 pm

I installed the Eco about three weeks ago.....I felt the power immediately. However I wasn't impressed with mt mileage last tank at 18.5 in town.

Joe Romas · **Posted:** Thu Oct 25, 2012 12:39 pm

Dano52 wrote:

I installed the Eco about three weeks ago.....I felt the power immediately. However I wasn't impressed with mt mileage last tank at 18.5 in town.

Your mileage figure may be caused by "winter fuel", it has less BTU's. It happens every year about this time :dizzy:

Dano52 · **Posted:** Thu Oct 25, 2012 3:18 pm

I hope that's the case.....although I would love better mileage.

papaindigo · **Posted:** Fri Oct 26, 2012 8:34 am

Dano52 if you are figuring mpg based on the odometer or the EVIC your figures could be way off. The EVIC is known to be wildly inaccurate although ususally on the high side. The odometer can vary +-5%, per spec, even with stock diameter tires and of course over or under stock diameter tires throw the odometer off even more. In addition single tank fill mpg can vary quite a bit based on pump accuracy, level of filling (only way to be sure of a consistent level is to fill all the way to the top of the neck), and fuel quality (winter fuel as noted cuts mpg, so does high % biodiesel, not to mention just bad fuel).

The only way to be totally sure of accurate mpg is to do a GPS correction factor for your odometer and do several consistent level fills at the same pump at a station with known good fuel or at least one that sellls a lot of diesel so the fuel isn't sitting in the station's tank for ages.

For what it's worth with the GDE Eco and Turbo tunes I've been getting ca. 23-24mpg in town but occasionally drop to 20mpg

Dano52 · **Posted:** Fri Oct 26, 2012 7:23 pm

Papaindigo, I've been using my odometer and didn't consider its inaccuracies. I know my speedo is off so that may affect my odometer too. I use my gps as the speedo. How do you recommend verifying distance with a GPS? Maybe my garmin has a function to do so I'll check. Thanks for your reply. Dano

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Joe Romas · **Posted:** Sat Oct 27, 2012 4:37 pm

Dano

The odometer is reportably 1.25% under reporting and the spedo reports around 6% over :SOMBRERO:

This is somewhat normal.
If the odometer were over reporting our warranty would be slighted and there was a class action against some Honda cars for that.
If the speedometer under reports you could tell the policeman your speedometer said you were not speeding. I think's there's a requirement mandating this does not happen :banghead:

papaindigo · **Posted:** Sat Oct 27, 2012 6:17 pm

Welcome to "electronic" instruments not a CRD specific issue. In today's cars the speedo and odometer are independent of each other in the sense that their error may be totally different or even opposite although in my experience both then to read high (ie. you are going slower than the speedo indicates and traveling further than the odometer indicates) and I'll leave you to speculate as to why. How to correct with a GPS:
1. speedo is pretty easy - find any flat straightish stretch of a mile or two and compare you speedo indication to your GPS. A bit of distance is in order as GPS unit vary as to how often they sample location and straighter is best as "cutting" corners can fool the GPS on speed depending on sampling frequency and how the software is programmed. No real need to use your GPS as the speedo just know that if the gauge speedo reads XX your are doing XX +- YY. In my case the speedo is almost dead on but in stoutdog's case the speedo is 2-3mph high.
2. odometer is similar but I like a longer generally straight and reasonably flat run (25 miles minimum or several runs and average). I use Excel for mpg calculation and just build a correction factor into the formula. FYI OEM tires had one correction factor while my current same size tires have a different correction factor.
3. EVIC has similar problems. Only instrumentation I know of that provides accurate EVIC type MPG figures would be a fuel flow meter integrated with accurate odometer and that's not generally fitted to street vehicles.

FYI I've played this game with a bunch of vehicles, same model or different, and results are all over the map even with the same vehicle and new tires of the same brand and same size. That said all my results are in the "acceptable" +-5% accuracy range for production uncalibrated (not Highway Patrol) vehicles.

jinstall · **Posted:** Sat Nov 03, 2012 8:37 pm

I used the ECO portion of my Garmin GPS to track my fuel usage, it seems on par with what everyone else gets. The odo tracks about 3-5mpg less.

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