Mass airflow sensors.

[Andrew Brownsword]

Hello again,

I am looking at how to replace my car's stock airflow sensor (a VAF, or vane
airflow sensor) with some other kind.  I've worked out most of the logic
changes that are required in the ECU.  The main reason for doing this is the
highly non-linear nature of the VAF's output -- at high airflow rates the
device saturates and large airflow changes results in tiny voltage changes.

One possibility is a device made by Link Technologies called the Link AFM.
It is a computer with a MAP sensor and an RPM interface that generates a
voltage signal that can be hooked to the stock ECU's airflow input.  It is
programmable, allowing extensive tuning.  Its also expensive, and Link won't
part with an information about the shape of its output curve.

The other possibility is to install a MAF.  Unfortunately I know almost
nothing about MAF's and their output characteristics, and that is why I'm
writing to the list...

If I use a MAF, should I just ignore the IAT input?  What kind of MAF should
I use, and where should I get it from?  What are their output voltage curves
like?  What kind of processing should I do on the value from the MAF, or can
I just convert it straight into the internal airmass representation?  What
level of boost can a MAF sense? (my car has an aftermarket turbo, which is
the whole reason for doing this).

Thanks,
  Andrew



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