O2 feedback

[James Lawler]

At 09:15 AM 6/18/98 -0700, you wrote:
>Martin,
>	I disagree! When using EFI the fuel flow is the same if you
>don't change the injector timing, and the total non-fuel
>flow is the same if we don't change the throttle or RPM.
>Since the EGR valve replaces some of the air with
>exhaust(usually considered inert) gas the total oxygen flow
>is reduced so the Air Fuel Ratio gets richer.

I would think that the behavour would depend on what type of air sensor is
in use. With MAF the AF ratio should be constant as the MAF sensor is
measuring the flow of fresh air into the engine. When the EGR is opened
allowing a percentage of inert air into the manifold (after the MAF) that
would decrease the amount of fresh air measured by the MAF. The fuel would
be adjusted accordingly.

With MAP the system would have to compensate for the decrease in fresh air
as the MAP would be measuring the total pressure of the fresh air as well
as the EGR gas.


James Lawler james at ccnsinfo.com

84 Mustang SVO E/SP
90 Eagle Talon AWD E/SP (Rain car)