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EVIC Error
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=14919		 Page 1 of 1
Author:  litton [ Mon Nov 27, 2006 9:58 am ]
Post subject:  EVIC Error
Does anyone know just where the EVIC gets it inputs from to calculate Avg MPG? I have about a 10-12% error (high) compared to actual and the Dealer can't find out why. We thought it was the fuel sensor and that was replaced but no help....might have even gotten worse. The sensor almost acts likes it's calibrated for the density of gasoline not diesel.....naaa, DC wouldn't do that would they?

I have even tried to get the operting logic but no one in the service loop can answer the question so I'm left to wonder what is going on. One concern is that the fuel consumption is assumed based on either speed or throttle position but my engine is injecting more fuel then it should.

Has anyone else looked into this problem.
Author:  MrMopar64 [ Mon Nov 27, 2006 11:12 am ]
Post subject: 
The EVIC receives the MPG data directly from the engine's ECU. It is calibrated to be approximately the same percentage high as you're reporting. Just the way that DCX requests it to be calibrated...
Author:  litton [ Mon Nov 27, 2006 11:23 am ]
Post subject: 
I was afraid of that. Thanks for the input.
Author:  greiswig [ Mon Nov 27, 2006 1:33 pm ]
Post subject: 
MrMopar64 wrote:
The EVIC receives the MPG data directly from the engine's ECU. It is calibrated to be approximately the same percentage high as you're reporting. Just the way that DCX requests it to be calibrated...


Odd...although I haven't measured in some time, for the first few months I calculated mileage by hand, and found the EVIC to be pretty much on the money...until I changed tire sizes without having the ECU reprogrammed for the new diameter. But even then, it was off by the "right" amount according to the circumference change.

I guess now would be an appropriate time to write YMMV.
Author:  KenJennings [ Mon Nov 27, 2006 4:40 pm ]
Post subject:  Re: EVIC Error
litton wrote:
Does anyone know just where the EVIC gets it inputs from to calculate Avg MPG? I have about a 10-12% error (high) compared to actual...

That's nothing. My EVIC MPG has run from 20% to 25% higher than reality. If you find an answer to it, my Dealer would love to know.

The EVIC usually tells me the mileage that most other CRD owners report (25 to 26.5 MPG) given my driving style -- predominately highway driving and keeping to 1800-2000 rpms as much as possible. It appears as if the EVIC is measuring all the variables properly, but something occurs afterward to put the CRD into some kind of "least efficient" mode and I usually end up with 20MPG (+/- 1/2MPG) when calculated at filll-up.

I did an experiment where I drove it like a granny for a tank, and later drove it like I stole it for another tank, and still the calculated mileage at fillup worked out to the same 20MPG. An interesting point is that when driving it irresponsibly, the EVIC and the calculated MPG did actually agree on 20MPG.

The weird exception is the last tank at 10,000 miles. For no reason I can figure the CRD did a real 23.7MPG average on the tank. (Only 2.4MPG less than the EVIC reported.)
Author:  midwest [ Mon Nov 27, 2006 5:11 pm ]
Post subject: 
No EVIC here, but I usually average 23.5 with mixed driving. Got 25 once going cross country loaded down at 75 mph plus---I liked that!
Author:  Jeger [ Mon Nov 27, 2006 5:23 pm ]
Post subject:  Re: EVIC Error
KenJennings wrote:
litton wrote:
Does anyone know just where the EVIC gets it inputs from to calculate Avg MPG? I have about a 10-12% error (high) compared to actual...

That's nothing. My EVIC MPG has run from 20% to 25% higher than reality. If you find an answer to it, my Dealer would love to know.

The EVIC usually tells me the mileage that most other CRD owners report (25 to 26.5 MPG) given my driving style -- predominately highway driving and keeping to 1800-2000 rpms as much as possible. It appears as if the EVIC is measuring all the variables properly, but something occurs afterward to put the CRD into some kind of "least efficient" mode and I usually end up with 20MPG (+/- 1/2MPG) when calculated at filll-up.

I did an experiment where I drove it like a granny for a tank, and later drove it like I stole it for another tank, and still the calculated mileage at fillup worked out to the same 20MPG. An interesting point is that when driving it irresponsibly, the EVIC and the calculated MPG did actually agree on 20MPG.

The weird exception is the last tank at 10,000 miles. For no reason I can figure the CRD did a real 23.7MPG average on the tank. (Only 2.4MPG less than the EVIC reported.)


10,000 miles? I bet you are just getting broke in, thats why your mileage might go up. Mine is still creeping up at 15,XXX, even with winter fuels coming into play. I cant wait till spring, As my mileage goes up the EVIC seems to agree a little better with my calculations long trips on the highway do throw the evic on the high side though
Author:  Cowcatcher [ Mon Nov 27, 2006 5:55 pm ]
Post subject: 
My EVIC does a great job except that I suffer from the speedometer/odometer errors that we mostly report and need to adjust for that. I think it is more reliable than the variences I would get in my tank fill on a diesel.
Author:  Teleri [ Sat Feb 08, 2014 7:01 pm ]
Post subject:  Re: EVIC Error
Newbie here to ask a question - please be gentle :oops: :oops:

I have an 05 KJ (in the UK it is labelled as a Cherokee) the EVIC shows the MPG somewhere between 2.1 and 2.3 mpg (now I know I'm a mere female known to have a heavy right foot) but in reality am averaging 25 mpg (UK measures)

Now I know in the scheme of things it's not a major issue but it really irritates me.

Any thoughts :?:
Author:  papaindigo [ Sun Feb 09, 2014 9:41 am ]
Post subject:  Re: EVIC Error
I'll have to speculate a bit and you might want to PM someone like Lancer (UK member) who might have a better answer or perhaps Keith at GDE (http://www.greendieselengineering.com/g ... ethod=home)

Thoughts:
1. the EVIC mpg is notoriously inaccurate in most vehicles although its direction and amount of inaccuracy seems to be consistent on each vehicle. That said if you actual mpg is ca. 25 I would expect the EVIC to read in the 22-28mpg range. That makes me wonder if for some strange reason your EVIC has placed a decimal in between the 2 numbers or if you are seeing a decimal that's not really there. Absent a decimal an EVIC reading of 21-22 vs. actual mpg of 25 is not too bad.
2. if not try disconnecting the battery for say 1/2 hour and reconnecting which might "reboot" the EVIC.
3. if not try, see Owner's Manual, toggling the EVIC between whatever unit of measurement settings it has. Here in the US those options are metric and US. This might also reset the EVICs units to get rid of a decimal. In metric mode I'd expect say 4-8 miles per litre. Of course if your hand calculation is using Imperial Gallons and not US gallons and the EVIC mpg is in US gallons that will complicate matters.
Author:  Teleri [ Sun Feb 16, 2014 7:28 am ]
Post subject:  Re: EVIC Error
OK I've done what was advised :SOMBRERO: , disconnected the battery for the required time and had a Math teacher friend do the conversion calculations for me (in both UK and US and Metric measurements) - the bad news it that the EVIC is still giving me 2.3mpg with an actual mpg in US gallons of 17mpg. :shock: I have also realised that when the fuel tank is full (71 litres at the last fill) the EVIC tells me that I have 18 miles left before empty :roll:

Short of replacing the EVIC I think I will just use it for telling me the temperature outside. MY OH says that it is a minor irritation and as the car is running fine to let it be and just enjoy the car.

Many thanks for the advice
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