Misc ?? EFI

thergen at svn.net thergen at svn.net
Sat Nov 21 22:12:32 GMT 1998


On Sat, 21 Nov 1998, Bill the arcstarter wrote:

> It was written:
> >>     While in PE it stays closed loop but it no longer is in learn 
> mode,
> >> meaning that the BLM and INT values are no longer being modified, the
> >> same thing happens on closed throttle deceleration, it stays in 
> closed
> >> loop but learn mode turns off.  
> >
> >On Fri, 20 Nov 1998, Scot Sealander wrote:
> >
> >> When in PE, the process is open loop, i.e., the feedback device is 
> not
> >> being used.
> >
> >I've seen both these conflicting viewpoints expressed before.  To me,
> >"closed loop" refers to a control process that is presently using 
> feedback
> >(like an O2 sensor) to maintain some parameter (like AFR).
> >
> >It may be just a question of semantics, but I think it is hindering 
> some
> >of the discussions.  If we can't all be on the same page, knowing what
> >individuals mean by their use of "closed loop" may be good enough.
> 
> So it sounds like there are two different processes to consider:
> 1) The processing of the self-learn, ie, adjustment of BLM, INT values
> 2) The injector fuel delivery is trimmed based on O2 and other sensor 
> inputs.
> 
> I would nominate the term "Closed-loop" to mean item #2.  Any comments?
> 


In my opinion...
All sensor inputs are not necessarily "feedback"  devices.  While TPS and
MAP do provide sensory input that help the ECM make decisions about fuel
and spark delivery, they don't provide this info based on what the
process (AFR) the ECM is trying to control. The O2 sensor does provide
info to the ECM on how succesful the ECM was in reaching its AFR goal
[during closed loop operation], so I would consider the O2 sensor a
"feedback" device that participates in closed loop control of the AFR
[during closed loop operation].

So, fuel delivery is always based on sensory input (even during learn
mode), but sometimes it's closed loop and other times it's not. 

This is my interpretation, I'd like to hear others' opinions.

Thanks,
Tom    





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