Idle fuel mixture setting

[Bohdan.L.Bodnar at att.com]

Dirk, et al.,

Idle actually runs richer than 14.7:1.  There are several reasons for
this (such as longer exhaust scavanging time at idle than off idle).  I
also know that some engines which do not use heated oxygen sensors run
open loop at idle;  this is because the O2 sensor will cool off and present
incorrect readings to the computer which will then cause the engine to
"hunt" as the air/fuel mixture varies wildly.

I have some *good* auto mechanics books at home which cover this topic
qualitatively;  send me e-mail if you're interested in the titles, ISBN,
etc.  I think the particular book I have in mind also has a table
listing approximate a/f ratios for various operating conditions.

Regards,

Bohdan
bohdan.l.bodnar at att.com