Mark McCulley wrote:

> I've seen the topic of AFM spring adjustment discussed on this list for
> years now and I still don't understand how spring tension can affect the
> mixture in a closed-loop system. The O2 sensor (in conjunction with the ECU)
> ultimately determines the mixture based on the amount of O2 in the exhaust,
> right? So what does changing the AFM spring tension really do?
>
> Mark McCulley
> Seattle WA

I'm new to this topic, but it seems to me that the AFM tension needs to be "in
the ballpark" to give the O2-ECM loop a chance to work correctly.
  If your mpg is respectable and you don't have relevant drivability problems, I
wouldn't mess with it.  "If it ain't broke, don't fix it."
   But then again, inquiring minds want to know...

Larry A.