Air flow measurement
kleenair at ix.netcom.com
kleenair at ix.netcom.com
Tue Nov 26 21:27:08 GMT 1996
Todd Knighton wrote:
>
> > Through all the discussions regarding air flow measurement, I think we have established that using a MAF sensor
> > as the main input generally results in some error due to air flow reversion. I have two questions:
> >
> > 1) What is the best way to quantify the error on an actual engine?
>
> We typically just let the mass air flow sensor think whatever it wants
> and write in a trim map, just like you would a pressure sensing system
> to compensate for the volumetric efficiency curve. As long as the
> condition is repeatable, who really cares if the computer thinks it's
> getting 10% more flow at a given rpm because of reversion effects, as
> long as you can trim the fuel quantity repeatably to a good output fuel
> number. If you're trying to use a maf for high resolution data
> aquisition however, you'll have to put a very large plenum between the
> engine and the maf to dampen out any reversion or pulsations and read
> only incoming airflow.
>
> Todd Knighton
> Protomotive Engineering
Thank you, this confirms my thoughts.
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