Do I need an Air Flow Meter?

[Jason R. Haines]

Some OE engine management systems have a table that modifies or corrects the
mass air flow sensor readings for changes in intake air temperature.

Jason

>
> > >> You mention that I would probably need a sensor for barometric
> pressure,
> > >> air temp, and RPM.  The stock AirFlow Meter doesn't have any of this.
> > > Doesn't have to, it's figuring mass
>
> > Just picking a nit, but the Bosch "flapper-type" airflow meters (as the
> > original poster was asking about) do have an air temperature sensor
built
> > into them, and provide it along with the flapper position.  The later
> > "hot-wire" type of airflow meters are themselves temperature sensitive,
> > so ambient temperature is accounted for automatically,
>
> It still is calculating MASS, which was the point.
> For proper tuning you need an air temp timing correction, IMO..
>
> > To the first poster, if you know airflow correctly, you don't need to
> > know engine speed.  Bosch K-Jet doesn't have an engine speed input.
> > It does usually have some input related to the throttle position
> > (depending on the type, this is either a MAP reference, or a TPS).
>
> He was talkingabout removing it, and then to approximate the air being
> consumed you need rpm, if designing a system other then AFM, or MAF
>
> > > Just too hard in my opion to get enough resolution in using just a MAP
> to
> > > do it. Hard to tell at times if your actually doing what ya seem to be
> > > doing because of Baro.
> > I would think that MAP would be directly related to barometric pressure,
> > since lower barometric would automatically mean lower MAP for otherwise
> > identical conditions.  Since you want less fuel at altitude, and you'd
> > get a lower MAP value at altitude, a fuel curve matched to MAP, with
> > throttle compensation for acceleration, would be adequate.
>
> Try doing it for a while and check back with me.
> I would be much easier to develope a single table of 10 items then having
to
> do one of 100+.
> To get the *proper* resolution IMP.
>
> > It's funny how many people are suddenly showing up wanting to replace
> > airflow meters with MAP output.  I'd thought about doing exactly the
> > same thing to by L-Jet equipped Alfa.
>
> By no means new.
> Bruce
> >
> > james montebello
>
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