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dgeist
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Joined: 21/07/2009 10:57:32
Messages: 10
Location: Atlanta, GA
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Based on several reviews, the factory EVIC computer seems to be even LESS accurate after a GDE tune.

With my current tire diameter, etc. , my factory stock EVIC odo setting is pretty close to accurate and I'd like to keep it that way if/when I do the GDE tune. I have to assume that it's calculating MPG from some internal formula in conjunction with some ODB or internal proprietary bus value related to injector firing or fuel-pump sensor foo. Has any work been done related to keeping the EVIC accuracy at least as good as stock (assuming it's something that CAN be altered)?

Thanks.
Dan
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GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 373
Location: Southeast Michigan
We tried to adjust the curve that controls the instantaneous fuel economy, but there are several inaccuracies in the lower end of the fueling curve. With the GDE tune less fuel is used and it operates more at the lower end of the inaccurate fueling curve, thus making the EVIC read slightly higher fuel economy. The software is very limited here.
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dgeist
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Joined: 21/07/2009 10:57:32
Messages: 10
Location: Atlanta, GA
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GreenDieselEngineering wrote:We tried to adjust the curve that controls the instantaneous fuel economy, but there are several inaccuracies in the lower end of the fueling curve. With the GDE tune less fuel is used and it operates more at the lower end of the inaccurate fueling curve, thus making the EVIC read slightly higher fuel economy. The software is very limited here.


So, to summarize, you tried to do some adjustments within the limits of the EVIC's API, but since it's limited, it's still not quite accurate, but better than if you would have not tried at all?

Dan
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GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 373
Location: Southeast Michigan
A couple days ago we released a slight change to the EVIC calibration. The slope was reduced by about 8%. The effects vary based on driving condition. Here are the limited results we have thus far. In highway cruising the EVIC was reading about 1.5mpg high and in city driving it was reading about 1.0 mpg low, so the end result with mixed driving should be more accurate than stock.

The input for the calculation is a non dimensional fuel flow rate, then corrected with slope factor and finally divided vehicle speed. The flow flow rate is based on the injector flow maps from the factory test bench, these are not accurate at low fuel flow rates, so this messes up the overall accuracy. If the odometer is not reading the same as GPS, the accuracy will also suffer. Even with all this, we think the cal change is directionally correct for having the EVIC reflect reality and not be so biased to the high side.
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LOSTCRD

Joined: 18/07/2009 22:51:54
Messages: 26
Location: San Antonio, Texas
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Honestly, I don't know how accurate the EVIC is in general...when you are putting it against hand calculations. You would really need to run thru about 10 good fillups (200 or so gallons) and then compare results to get a good idea IMO.

2006 Jeep Liberty CRD...OME Lift...ASFIR Aluminum Skids and Steps...

DarbyWalters @ L.O.S.T.
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dgeist
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Joined: 21/07/2009 10:57:32
Messages: 10
Location: Atlanta, GA
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GreenDieselEngineering wrote:A couple days ago we released a slight change to the EVIC calibration. The slope was reduced by about 8%. The effects vary based on driving condition. Here are the limited results we have thus far. In highway cruising the EVIC was reading about 1.5mpg high and in city driving it was reading about 1.0 mpg low, so the end result with mixed driving should be more accurate than stock.



I think I was the recipient of one of the first programs after you made that change. The EVIC output looks to be a few ticks higher than what I had been hand-calculating, so that would be consistent with the numbers that others are posting. I'll report back once I have a full tank of fuel with the E-T and some more highway driving for data points.

Dan
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SVO Ryan
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Joined: 20/07/2009 01:07:28
Messages: 10
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My EVIC is ~3mpg off at the end of a tank's life.

Ryan
2005 Liberty CRD
GDE Tune//TransGo Shift Kit//PML Deep Pan//MBRP Exhaust//LoTek Dual Gauge Pod//ProSport Tranny Temp and Boost Gauges
1986 Mustang SVO
WXman
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Joined: 29/01/2010 14:53:49
Messages: 28
Location: Kentucky
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I'm going to miss my EVIC. I use it a lot.


Edit: With the GDE tune, my EVIC seems to be anywhere from 2 to 4 MPG optomistic at the end of a tank so far.

'05 Liberty CRD Limited
Factory Off-Road Package
Daystar spacer lift/Conduit washers
Skyjacker H7088s in the rear
Renegade wheels
255/70-16 General Grabber AT2s
GDE HOT Tune
EHM
No clutch fan
"Euro" TC
GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 373
Location: Southeast Michigan
Does anyone have additional tank and EVIC fuel economy numbers? We would like to verify the accuracy of the EVIC tune that was implemented late October. We are hoping the trends point to having the EVIC a little closer to reality. Thanks for the feedback.
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TDIwyse

Joined: 01/10/2009 06:58:20
Messages: 54
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GreenDieselEngineering wrote:Does anyone have additional tank and EVIC fuel economy numbers? We would like to verify the accuracy of the EVIC tune that was implemented late October. We are hoping the trends point to having the EVIC a little closer to reality. Thanks for the feedback.


Since getting the new EVIC cal on the HOT tune back in January these are the tanks (plus 2 data points I thought were interesting) where I've left the EVIC alone from one fill to the next.

date EVIC HandCal

1/12/10 23.1 21.7
1/22/10 xx 21.9
1/28/10 26.0 23.9 * Switched from Cooper Discover ATR 215/85R16 to General Grabber HTS 235/75R16
2/3/10 25.1 24.4
2/6/10 27.8 25.8
2/11/10 26.0 24.0
2/16/10 28.2 24.9
3/3/10 xx 27.8 * Started blocking the cold air intake
3/7/10 30.1 27.9 * Continued blocking the cold air intake

The EVIC is much more accurate than the previous ECO tune results. It's still optimistic, but somewhat consistent in its optimism.

2006 Liberty Limited CRD
2004 Ram Quad Cab 4x4 Cummins
2001 VW Jetta TDI
1990 YJ with 2006 Cummins B3.3T
GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 373
Location: Southeast Michigan
How does the accuracy of the EVIC now compare with the EVIC when stock? Based on your measurements we could maybe tweak it a little more. Would you be interested in a replacement ecu with a new setting to test?
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WXman
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Joined: 29/01/2010 14:53:49
Messages: 28
Location: Kentucky
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I'm seeing the same results as him. EVIC is still 2 to 4 MPG optomistic at the end of a tank. On the Interstate, it's closer to 4. Around town it's closer to 2. The good news is that it seems to be consistent. So I can always look at the EVIC, subtract 3, and have a pretty good idea of what I'm really getting.

Bone stock the EVIC in mine appeared to be 1 to 2 MPG optomistic.

'05 Liberty CRD Limited
Factory Off-Road Package
Daystar spacer lift/Conduit washers
Skyjacker H7088s in the rear
Renegade wheels
255/70-16 General Grabber AT2s
GDE HOT Tune
EHM
No clutch fan
"Euro" TC
TDIwyse

Joined: 01/10/2009 06:58:20
Messages: 54
Offline
My CRD didn't come with an EVIC when I purchased it used last August. I wired in an EVIC from an old Grand Cherokee last November which was after I already had your Eco tune. Then I changed to the Hot tune. Next week I will likely contact you about your turbo kit if I can get those turbo housing bolts to break loose . . .

The only other vehicle I own with a computer mpg display is my 2004 Ram Cummins. In the winter it is usually optimistic, but in the summer it's pessimistic. Until I see how your present tweak works in the summer I'm not sure if I would want it changed.

GreenDieselEngineering wrote:How does the accuracy of the EVIC now compare with the EVIC when stock? Based on your measurements we could maybe tweak it a little more. Would you be interested in a replacement ecu with a new setting to test?

2006 Liberty Limited CRD
2004 Ram Quad Cab 4x4 Cummins
2001 VW Jetta TDI
1990 YJ with 2006 Cummins B3.3T
 
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