01-03-2008, 01:46 PM
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75/Milano manuals for all
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Join Date: Apr 2004
Location: Melbourne Australia
Posts: 1,799
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 Quote:
Originally Posted by Razzo rosso
however there is still the debatable issue of how best to measure air inflow temp.
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Ah, this is an interesting one.
The way I see it:
First off, you don't need to measure the temperature during engine operation as this is already done in the MAF. The ECU requires the temperature when using an AFM as the AFM only provides the volume of air not how much oxygen is in that volume. To calculate how much oxygen the ECU needs the temperature to calculate the density of the air, which with the volume, the ECU can calculate the density and mass then how much oxygen.
Since the output from a MAF (hot film or hot wire) IS mass, the ECU does not need to know the current temperature BUT because the calculation will still be made it needs a fixed value for temperature.
But what fixed value? That is the question.
Probably the current air temperature when calibrating your signal conditioner.
But then it might be something like the ISA 15°C or it might be some value Bosch picked. 
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