Odometer Calibration

Upon installing my trip minder, I did a quick check, and found that the tripminder and the trip odometer were both EXACT in their calibration to eachother. Meaning, that when the trip odometer rolled over a tenth of a mile, within a second the trip minder showed another tenth of a mile. And that was after over 30 miles of operation, so they're pretty bleeding accurate.

The problem is, they're both inaccurate when compared to the road signs.

I stopped right next to one of those little blue signs by the side of the highway and set the trip minder to 0. Within 7 miles, it was more than a full tenth of a mile off.

Is that normal? It's only about a 2% error, but still. If it's not a normal margin of error, how would I calibrate it?

Considering the tripminder uses the same pulse signal from the sensor as the speedo, they better be exact! But otherwise I've noted similar readings as you with mine. I've chalked it up to not trusting those "check your mileage next 5 miles" signs. Mine's pretty mich dead on with roadside radars and speed between 40mph and 80mph. So I don't care.

If you go upping your fuel pressure the gallons used start to be behind actual usage also....

2% error is well within spec.