Air Flow Measurement

[Scot A. Sealander]

oecar1 at oec4.orbeng.com.au wrote:

[big snip]

> There's heaps more to be said about this subject but I hope it's
> useful to share this with you guys.  If anyone has any other ideas or
> experience on getting MAF's to work well, I'd love to hear from them.

Andrew, I think you did a great job describing some of the problems!

As to average MAF value with big sample to sample deltas in normal use, I 
have seen OEM code that addresses this.  There is often a delta rate 
limiter (can be asymmetric) that can keep the sample to sample variation 
under control. I have never plotted the Raw MAF to gps tables to see what 
the actual curve looks like. It is very obvious that it is not linear.  
Maybe when I get some time.....

It seems the frequency type MAF (digital) may have better resolution than 
the 0 to 5 V MAF, but that resolution may not be useful :-)  

As far as MAP's, I have also seen OEM code that attempts to keep the MAP 
samples taken about the same time in the engine cycle.  It seems that 
this would make for less sample to sample variation. (That could be all 
wrong....)

 
> Andrew Rabbitt
> Orbital Engine Company
> Perth, Western Australia

Scot Sealander 

In northeast PA....USA