Author Topic: UG's average and instantaneous MPG way off  (Read 12203 times)

Offline Ro3bert

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UG's average and instantaneous MPG way off
« on: January 01, 2012, 08:15:56 AM »
Got the scare of my life the other day. I’d finally installed my UG and was testing it. Worked great.

Set the engine size and fuel tank capacity ( 3.0 L and 25 USG [BTW it is a 2011 2500 MB Sprinter high top 144 inch wheel base]) and when I left my bumpy gravel road and got onto pavement, up a 8% or 9% grade the instantaneous MPG read 1.5 or so, scared the bejesses out of me.

Out on the road on a 400 mile trip the average MPG got up to slightly over 8.6 while the instantaneous MPG ran from about 5.6 to 9.5 (or there abouts).

Now I keep meticulous fuel records so know that over the life (a whole 5900 miles) that the average MPG is slightly over 20 which doesn’t jibe with the UG figures.

I have not yet “calibrated” UG yet but it seems to me those figures are a bit (lot) low. Obviously I’m going to have to get out on the road to do the calibrating but reading the instructions it seems extremely complicated. Added to that I live in Connecticut where there are no straight, flat roads and few mile markers. I will have to go over the border to New York and do a ten mile calibration and see if that works miracles.

So I ask is the calibration process going to bring UG’s figures nearer to the calculated average MPG?

Robert 

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Re: UG's average and instantaneous MPG way off
« Reply #1 on: January 01, 2012, 04:37:40 PM »
Since you have a Diesel, you must calibrate it otherwise UG will be way off.  The calibration process is simple.  Just follow each step listed in the manual.

Offline Ro3bert

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Re: UG's average and instantaneous MPG way off
« Reply #2 on: January 02, 2012, 03:22:32 PM »
Thanks. I'm going to start tomorrow but one question; with a diesel engine (turbo charged) have to do the volumetric thingy first or just the mileage calibration? On the one hand the instruction say to do that first and on the other it says not to bother with diesel engines. So far the instructions (in some places) seem to be confusing.

Robert

Since you have a Diesel, you must calibrate it otherwise UG will be way off.  The calibration process is simple.  Just follow each step listed in the manual.

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Re: UG's average and instantaneous MPG way off
« Reply #3 on: January 02, 2012, 03:49:29 PM »
If you vehicle has a MAF sensor, then the VE is unimportant.  If you do not have a MAF sensor, then I would lean toward enabling the volumetric efficiency first.

Offline Ro3bert

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Re: UG's average and instantaneous MPG way off
« Reply #4 on: January 02, 2012, 03:57:27 PM »
If you vehicle has a MAF sensor, then the VE is unimportant.  If you do not have a MAF sensor, then I would lean toward enabling the volumetric efficiency first.

Thanks again, I'll check for a MAF sensor first thing in the morning then go from there.

Robert

Offline suzieque

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Re: UG's average and instantaneous MPG way off
« Reply #5 on: January 07, 2012, 02:05:27 PM »
your sprinter has a maf

did you get the fuel economy calc to work?

Offline Ro3bert

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Re: UG's average and instantaneous MPG way off
« Reply #6 on: January 08, 2012, 06:07:53 AM »
your sprinter has a maf

did you get the fuel economy calc to work?

Yes I did, unfortunately it didn't bring the average (or instantaneous) up any where near my calculated average. The calculated average is running just over 19MPG (over 6000 miles of fill ups) while the average MPG on the UG is about 10.8. The  (on the highway) runs from about 8 to 15 with the normal about 10 (16 to 21 down hill).

Oddly enough when I first start to decelerate the instantaneous goes way up but under continuous decel ( like long hills) the number starts to drop by a large amount.

The fuel economy calc was over a 20 mile stretch of winding, hilly roads ( I-84 in NY). They aint no straight roads in the north east.

The next time I get to PA going to or from a job on I-80 I'll try for a 200 mile calculation.

Haven't tried the VE enable yet as the UG ADMINISTRATOR suggest so will have to try that, I can always disable it if nothing changes for the better.

Robert

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Re: UG's average and instantaneous MPG way off
« Reply #7 on: January 08, 2012, 08:18:21 AM »
VE is ignored on vehicles with MAF sensors.

Offline Ro3bert

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Re: UG's average and instantaneous MPG way off
« Reply #8 on: January 08, 2012, 06:10:53 PM »
VE is ignored on vehicles with MAF sensors.

So why did you suggest I enable it in an earlier post?

Robert

Offline jan

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Re: UG's average and instantaneous MPG way off
« Reply #9 on: February 02, 2012, 11:46:42 AM »
"If you vehicle has a MAF sensor, then the VE is unimportant.  If you do not have a MAF sensor, then I would lean toward enabling the volumetric efficiency first."
If you did read it all (and it isn't much) you would have known VE is not important in your case.

If you have (or can borrow) a GPS, you can also calibrate the distance via the speed. If the speed on your ultra Gauge is e.g. 3% too much compared to the GPS, you have to correct the distance calibration by -3%. The speed on a GPS is verry accurate.