FC 45

[JTesta1966 at aol.com]

In a message dated 5/20/99 8:28:48 AM Eastern Daylight Time, 
m.s.bower at cummins.com writes:

<< Hey guys,  I could use some advice on this.  I have a 93 s10 blazer with
 cpi.  It's setting a fualt 45.  Using the scan tool I am seeing that
 when I cruize at highway speeds the O2 sensor voltage will hold at .85
 volts and after a couple of minutes it will set the code and kick it out
 of closed loop.  It then holds O2 volts at .92 and will stay usually
 until I go back to start stop driving at which point the ecm goes back
 to closed loop and the O2 sensor starts swinging from .1 to .8 volts. 
 Any ideas as to what I am not seeing here?
  >>

Check for a ported vacuum leak, check EGR operation, check that you havent 
set up a "too lean" lean cruise mode in the calibration.

Jim