Most all OBDII vehicles have a flow meter. So far every vehicle I've jacked into has a flow meter (GPH). Only 10% of vehcles report fuel pressure.

Now as for calibrating is easy. Plug in the ScanGauge II and then go fill up the vehicle with fuel. Now go for a ride somewhere and burn a few gallons. Now return back and fill up again. ScanGauage II will show how many gallons was burnt. Now adjust the amount of gallons burnt to match what you filled up with. ScanGauge II will display a offset percentage. Here is a few I know...

2002 Dodge cummins S0 Engine with Edge Comp (2.3% Offset)
1996 Dodge 1500 V8 with Mopar Performance Box (233% Offset)

Now when I plug into either one of my trucks I get a very accurate flow and usage report from the ScanGauge II. You can re-do the calibration everytime you fill up if you want too. But when I roll in to a fuel station I know exactly what I'll spend in fuel...

Current displaying my Mom's 1996 Dodge 1500 (5.9L Gasser)


$11.70 to fill up...


3.23 Gallons worth of fuel at todays prices...


But I've got 21.8 Gallons remaining..


I can report hours of fuel remaining as well... Not to mention Current (actively driving), today totals, yesterday's totals, and totals for the entire tank. Usually when I pull up to a fuel station it right on the money for amount. But there is a bit of error between the measure of the pump your using, slope of ground (incomplete fill), etc. So If I'm +/- 0.2 gallons I figure I'm good for calibration but if it falls outside I re-run my calbration again. Once again this is something stock "Overhead Idiot" can't do..

 

If your lookin to be techinical about all this there's a flaw here. If you fill up then drive a few miles and fill up again and use this as your calibration setting for your scan gauge your gonna be wrong. Unless your filling your tank up to the opening of the filler neck where you can see it, there is no way of telling exactly how full you are gettin the tank. Between the differences on pump sensitivity for auto shut off, expansion differences for fuel temperature and foaming you could have a gallon or more difference in what your calling filled up. This is ok for general purposes but not if your lookin at it from the technical aspect that you are working off of.

 

That why I edited my post because I know there is a bit of error to this but is usually really close to being dead on...

During calibration I fill till it in the neck. so I can get as close as possible to true. But Still afterwards the flow rate is right there. I can do the math MPG again the ScanGauge II numbers and match most of the time.

 

Just because the gauge is close does not mean there is a flow meter built in.

Where is the meter in the VP? Someone has to have taken one apart and found this device.

Dave