Thread: OBDII Data Logging TP

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2010-09-20 23:27:49

#31

bbekov

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Originally Posted by dfddfd2

Yes, it's the TP used for both fuel and timing maps. the problem you may run into is how the value is reported. Datascan will probably report it as a voltage, but you should be able to take that value * 200 / 256 to get TP as used in the maps. Try it and see.

Dave

Why we have to do the calculation that way (multiplying by 200/256) exactly? Isn't the voltage corresponding to a value from the VQ translation table (0-65535)?

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2010-09-21 00:11:30

#32

OnTheChip

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Originally Posted by bbekov

Why we have to do the calculation that way (multiplying by 200/256) exactly? Isn't the voltage corresponding to a value from the VQ translation table (0-65535)?

Good question. Datascan thinks (I'm guessing) that the 16bit value in the 2 consult registers is the analog to digital conversion of the raw O2 sensor voltage, and will probably divide it by 200 to display it as a voltage. ie; If Datascan shows 8.36V, then the actual 16bit value is 8.36*200 = 1672. Since the value in the registers is total TP (not the value from the VQ table), that value must be divided by 256 (1672/256=6) to get the load TP=6 used in the fuel and timing maps.

Cheers,
Dave

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