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Old 01-15-2008, 02:34 PM   #1 (permalink)
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question about scanguage - how to make an OBD2 tool do MPG calcs

I was wondering if someone can help me figure out what the scanguage uses to display gas mileage, etc. I have a datalogging program that i can use when Im racing my car, and it gives me basically the full OBDII set of info (and then some). I was wondering if I could use this information, then modify an output in some way to let me know instantaneous info like the scan guage. This wont be as easy to look at as the scan guage, but it would be free, so thats always good. I would think that it may be something as simple as engine load( a calculation based on airflow v. engine rpm) against vehicle speed. Any thoughts?

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Old 01-15-2008, 02:53 PM   #2 (permalink)
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If you can get airflow (mass) from the OBD2 port, you should be able to do a simple instant fuel economy calculation based the stoichiometric air fuel ratio of 14.7 to 1. Factor in your speed, and you're good to go.

The SuperMID works by using a (user-programmed) volume for the fuel injector. It counts fuel injector pulses per distance traveled and bases the calculations on that.
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Old 01-15-2008, 06:13 PM   #3 (permalink)
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thanks, I was wondering if it was really that simple or not. This becomes one more reason for me to get an accurate air/fuel ratio sensor, so that I can get it to make exact measurements and then better calculations.
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Old 01-24-2008, 07:15 AM   #4 (permalink)
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Can the Scanguage II's MPH readings be calibrated for different gearing/tire size?
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Old 01-24-2008, 08:53 AM   #5 (permalink)
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Hi Chris - the answer is yes. You can enter an offset in the SG2 to correct for tire size or gearing changes, or a speedometer/odometer that was off from the factory.
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Old 01-25-2008, 12:26 AM   #6 (permalink)
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Are these easy to program?

Do we have any group buy deals rollin?
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Old 01-31-2008, 02:13 AM   #7 (permalink)
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the stoichiometric air fuel ratio of 14.7 to 1. IS NOT WHAT CARS BURN ALL THE TIME.IF YOU ARE WARMED UP AND ON THE LEVIL AND HOLDING THE SPEED OK MAYBE
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Old 01-31-2008, 07:18 PM   #8 (permalink)
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does this scanguage show oil pressue?
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Old 01-31-2008, 09:10 PM   #9 (permalink)
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Chris, that isn't one of the standard things that can be monitored. It may be possible through the x-gauge feature but that would depend on if the ECU for that make actually monitors it.

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