programming for a MAF based system

[socrace at ameritech.net]

    Your correct, RPM is not strictly needed with a MAF based system, if 
you don't mind asynchronous injection, but theres an exception (aint there 
always?).
    The exception comes in during choked flow (pressure drop accross 
throttle >50% or so). Ideal mass air flow will be a constant no matter what 
the motor is doing, because air velocity past the throttle is mach 1 and 
can go no faster. This occurs mainly, as you say during idle, but also 
light cruise, etc. So if air flow is constant and rpm drops, the increased 
air available to each firing causes the mixture to go lean, and MAF is no help.
Bob D

At 09:46 PM 3/14/2002 -0800, les wrote:
>Can someone point me to any hints for how to approach the
>algorithms for fuel calculations, as they apply to a mass air
>flow measuring fuel system?
>
>At first look, it seems that all the 'normal' variables needed for
>MAP systems just drop out of the equation. I suppose that I still need
>a 2d map , to allow for richening under boost, but it just seems too
>simple. I mean, other that for idle speed needs, rpm doesn't even seem
>to enter the equation. Air mass is air mass.
>I understand that the MAF is not linear, but a simple lookup table
>should
>fix that.
>
>-Les

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