Misc ?? EFI

[Bill the arcstarter]

Hello Scot, list,
Scot wrote:

>This is very true.  And in fact it usually does, except for some
>calibrations.  Sometimes if the ECM learned to remove fuel during 
cruise,
>it won't let it remove during PE.  An example may be someone who raises
>fuel pressure a considerable amount.  The ECM will compensate, and
>remove fuel.  But it may not remove fuel that it learned to remove 
>while in PE.

I'm assuming PE stands for Power Enrichment, as in WOT & ignoring the O2 
sensor, right?

That SAE paper about the O2 sensors was really quite damning.  It 
basically says those sensors are so sensitive to hydrocarbons that it 
can't even detect if one cyl is not even firing!

The amusing thing is that the auto ECU programmers must have known this 
since the ECUs all ignore the O2 under WOT (and possibly other conditons 
such as warm-up etc).  Why is this information so hard to find? (just 
whining a bit...)


>So the fuel equation may be:
>
>AirInCyl/AFR * injector constant * Int * BLM.

Sounds good.  Can anyone verify the accuracy of the above?  I've seen 
discussions of INT, BLM but never much detail on how they work towards 
tweaking the fuel delivery.

I'm assuming the dither is a component of the AFR in the above equation?  
That would allow the computer to look at the O2 voltage and determine if 
the engine is close to the ideal point...

I'm also assuming there are scaling conventions on the INT and BLM 
constants, ie, 128 decimal = "perfect, no adjustment =1.00", etc...  
Does anyone know the total amt of "adjustment" to the calculated fuel 
delivery which the INT and BLM can command?  I wouldn't think it could 
be very large, perhaps 20% or so?? (just a guess)

Comments invited!
-Bill

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