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thewanderer · 03-16-2015, 06:50 PM

The VSS seems to be perfect between the MPGuino and my 92 Civic VX, but the MPG reported via the MPGuino seems to be off considerably from what I measured at the pump...

I put 309.7 miles on this tank (MPGuino states 309.72, so that matches pretty well) According to the pump, I put 7.719 gallons in the car and on the MPGuino, it states 7.70 gallons.

But the issue is... 309.7 mi / 7.719 gal = ~40.12 MPG (pump) and 309.72 / 7.70 = ~40.22 MPG (what MPGuino should report) but the MPGuino is saying my tank MPG is 50.25 MPG, so it's off by a little over 10 MPG.

I had the uS/Gal set to 258562433 (I saw someone on the forum mentioned that number) so following the guide, I did (258562433*7.7)/7.719=257925992 and set the microsec/gallon to 257925992. But the small amount the gallons were off by (0.019 gallons) seems like the microsecond value was close... but I don't understand why the reported MPG is so much higher?

Am I missing something as to why there's such a discrepancy between MPG but not gallons or miles?

03-16-2015, 06:50 PM	#1 (permalink)
thewanderer EcoModding Lurker Join Date: Dec 2014 Location: PA Posts: 14 Civic VX - '92 Honda Civic VX Thanks: 1 Thanked 0 Times in 0 Posts	MPG accuracy / calibration vs pump MPG The VSS seems to be perfect between the MPGuino and my 92 Civic VX, but the MPG reported via the MPGuino seems to be off considerably from what I measured at the pump... I put 309.7 miles on this tank (MPGuino states 309.72, so that matches pretty well) According to the pump, I put 7.719 gallons in the car and on the MPGuino, it states 7.70 gallons. But the issue is... 309.7 mi / 7.719 gal = ~40.12 MPG (pump) and 309.72 / 7.70 = ~40.22 MPG (what MPGuino should report) but the MPGuino is saying my tank MPG is 50.25 MPG, so it's off by a little over 10 MPG. I had the uS/Gal set to 258562433 (I saw someone on the forum mentioned that number) so following the guide, I did (258562433*7.7)/7.719=257925992 and set the microsec/gallon to 257925992. But the small amount the gallons were off by (0.019 gallons) seems like the microsecond value was close... but I don't understand why the reported MPG is so much higher? Am I missing something as to why there's such a discrepancy between MPG but not gallons or miles?