Misc ?? EFI

[Bruce Plecan]

-----Original Message-----
From: Bill the arcstarter <arcstarter at hotmail.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>;
Sealand at clarityconnect.com <Sealand at clarityconnect.com>
Date: Sunday, November 22, 1998 12:06 AM
Subject: Re: Misc ?? EFI


>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!

Might help explain why some oem's look at crankshaft accleration rates for
miss detection.
Cheers
Bruce


>
>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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