Performance tracking of alternative fuels

The folks at Brevard BioDiesel installed a Linear-Logic "ScanGauge" in their 2004 TDI Jetta to try and help gather additional mileage data for future biodiesel reports.

The ScanGauge scans the built-in car computer to gather and report various engine and fuel data, along with a trip computer function.

The following readouts seemed to function with the Jetta TDI engine: Fuel Economy (MPG), Fuel Rate (GPH), Battery Voltage (Volts), Water/Coolant Temp (degrees), Intake Air Temp (degrees), Engine Speed (RPM), Manifold Pressure (PSI), Engine Load (%), Throttle Position (%). The following readouts were not supported on the 2004 TDI: Ignition Timing, Open/Closed Loop, Fuel Pressure.

Read more at Brevard Biodiesel's website.

The ScanGauge is compatible with most OBD2 equipped gasoline and diesel vehicles using a variety of fuels.

Hi Steve,

I have been using a ScanGauge for several months. Many of us that report in at www.tdiclub.com own ScanGauges or Vag-coms. It has performed well. I talked with the guy that runs the business-- seems very helpful, willing to keep his customers updated as the product improves.

The ScanGauge can be useful in understanding how driving habits affect mileage, or comparing car modifications, like opening a car window for example.

The MPG readout is really a nice feature, and works well at ordinary conditions. I find the best way to understand the mpg output is to put the readout on trip/summary. Then, reset when you start looking at a new situation. The gauge averages the mpgs from that point until you hit the reset button again. When the true mileage gets over about 70 mpg, the ScanGauge isn't able to get a reliable reading, it reads too high. I think that's not a fault of the ScanGauge, just hard to get reliable readings from the OBD port. Also, you need to calibrate carefully for your usual driving conditions. If you make a big change in speed or change to city driving, the calibration needs to be adjusted.

I have run numerous tests in which I compare fuel economy under controlled conditions. A ten-minute average reading (ScanGauge set at Trip /Current) gives reliable MPG numbers if you are sure there is no grade or wind. Otherwise, make two measurements in opposite directions. Frankly, I think there is always enough grade and wind, so make two measurements.

Examples:

1. Measured effects of tire pressure changes
2. Open windows versus closed
3. AC on versus off

You can find reports of this stuff at www.tdiclub.com

Ernie Rogers

VW Beetle wins fuel economy prize: 76 mpg