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Old March 15th, 2018, 14:12   #16
Vince Waldon
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Join Date: Apr 2009
Location: Edmonton Alberta Canada

ODB2-port gauges can only display sensors that are:

a) installed on the vehicle
b) monitored by the ECU
c) reported by the ECU via a PID

So, no oil pressure, oil temperature, or EGT on a 2004 BEW, for example, 'cause no sensors.

Because there's a MAP sensor boost can be reported, although it's slightly susceptible to the weather, since the MAP reads absolute atmospheric pressure, which varies a bit with the weather, altitude, etc. Actual analogue boost gauges read relative pressure... the manifold pressure relative to whatever the current barometric pressure is.

Also worth noting that the refresh rate over OBD2 can be a bit slow... maybe 1-2 Hz. Some find that a problem as a boost gauge.
Vince Waldon Edmonton AB Canada

Note: The above is to the best of my knowledge- but at the end of the day simply interweb opinion, worth EXACTLY what you paid for it, and if used done so at your own risk.

Last edited by Vince Waldon; March 15th, 2018 at 14:17.
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Old March 15th, 2018, 17:15   #17
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Join Date: Aug 2004
Location: Northern Minnesota-55744
Fuel Economy: 52+ average lifetime '01

My ScanGauges have been overall very accurate for mileage and I record/log all fuel fills/use from day one. The only big variances come when the driving routine changes drastically, such as a lot more in city or towing, etc. In those situations it's best not to "recalibrate" and just let it ride until you get back to a normal routine, or if/when you do calibrate only go half as much as the difference is or you get a big change. Another thing that causes the mileage to report off a bunch is to use VCDS to make an egr cycle chance, injection timing adjustment, etc. Anything the ECU "sees" and/or controls if altered will affect the mileage reported and affect accuracy until gradually calibrated to compensate.
Other than that they are usually within 1-2mpg of actual and often less than 1mpg variance. Much closer than most any factory built in trip/mileage calculator in any vehicle I've owned.
I did not like the UltraGauge. Buttons on the back made it hard to change data and check/clear codes while driving and the windshield mount was a joke in cold cold temperatures. I had it in the Suburban towing vehicle until it once again fell off the windshield glass and into the door hinge area as I was shutting the door. In testimony to its durability, it still "works" but the screen is shattered and unreadable. RIP...

2001 Jetta TDI GLS Silver-current driver (salvage)permanently vented-Panzer Plate-Sprint 520s-ScanGauge-CheckTemp III-ZeroStart heater-CAT 2 filter
2003 Jetta GLS Black w/leather (New Project Car) fixer-upper w/broken TB
2004 Cadillac SLS (wife's)
1999 GMC Suburban (It's MN-you need one)
197? Shibura 2cyl diesel 4WD tractor-loader/brushhog (very handy unit)
196? International TD340 Dozer-w/Drott 4-in-1 bucket/back ripper attachment
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