I'm missing something...

[Bob]

Isn't the reason for the MAP is to calculate the % Oxygen in
the air at different elevations?

MAF would still measure just the amount of Air entering the engine
 , even if it's Oxygen content is much lower at higher elevations...

or do I have it all wrong?

----- Original Message ----- 
From: "NickG" <nikog at mediaone.net>
To: <diy_efi at diy-efi.org>
Sent: Sunday, November 11, 2001 8:44 AM
Subject: Re: I'm missing something...


> A flapper door AFM can not compensate for changes in air density. The AFMs
> are 'airflow meters', but not 'mass airflow meters' like the current mass
> air meters. Thus, changes in elevation are not detected. That is why the car
> in question started running rich at higher elevations.
> 
> But, I would have expected the ECU to tempensate and adjust the mixture
> based on the O2 sensor's feedback. Unless, of course, the system is
> programmed to run in open loop or has adaption turned off.
> 
> Nick
> '95 M3 turbo
> 


----- End of forwarded message from owner-diy_efi at diy-efi.org -----
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