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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