Fw: Justa O2 Note

[xxalexx at ix.netcom.com]

> EFISYSTEMS at aol.com wrote:
> > 
> >  This is very true,,,I just spent the last six days datalogging a 99 chev
> > truck and have seen the AFR vary from 14 - 15:1 while in closed loop and is
> > intentional to reoxygenate the exhaust stream to further burn HC's since air
> > pumps would mess up the O2 sensors.....
> > -Carl Summers
> 
> Interesting... My cat is a 3-way type cat and I would assume that 
> they would have just triggered the AIR relay to inject more air 
> directly into the cat...   It bypasses the O2 sensor in this
> case....
> 
Your tube is in the middle of cat,  at begining of 2-way section not 
before in nox section.  A little dangerous to inject air at high 
speed, could cause melt down.  After the 70's radar trap brush fires
a vacuum regulated diverter valve was used, then air  injected 
only at cold start, by computer. this also helps meet the 120K mi. 
durability stds.
If A/F meadured with O2 sensor it could be a liitle difficult to keep 
a warmed up 02 sensor at exactly 14.7 at WOT for any length of time, 
if it was cycling at a constant frequency on a electric engine dyno, 
for 6 days with all parameters measured, is possible. 
alex