Re: O2 sensors

[QSHIPQ@aol.com]

In a message dated 97-11-11 14:57:01 EST, you write:

<< On turbos are there any real symptoms of a failing or failed o2 sensor?
 >Could my 1.3 bar bog be caused by it? I was under the impression that
 >maybe symptoms of a failing sensor are gradual and you don't really notice
> it until you change the sensor. Do higher boost levels affect it's life?
> Audis are built around the airbox? I say they're (at least turbos) built
> around the o2 sensor.
  >>
The bog is caused by something else, could be fuel related tho.  Remember,
the lamda circuit (O2) goes closed loop at WOT, in other words, it fixes a
value for the O2 circuit (voltage/Duty Cycle).  Not sure I understand the
latter part of the post, but a failing O2 can have the following
characteristics:  Intermittent FV operation at idle, poor idle, poor off
boost peformance, bad mileage (this one is my benchmark).  A DC or dwell
meter can be a good indicator as well.  As an O2 starts to fail, the variance
from it's read start to get wider.  IOW, put in a new O2, set to 42DC/37.5
dwell.  You will get a variance in that DC/Dwell of about +/-5 or less on a
new O2.  Older O2's will jump +/-10 or more as they fail.  

You certainly could have a fuel problem.  System Pressure and Control
Pressures should be tested periodically (change fuel filter first please),
you can save a lot of diagnostic time by making sure you have those correct
baseline.  An A/F meter might help you establish whether you are really
"lean" or "rich" and at what rpm.   Turbo cars with no fuel mods tend to run
a little rich at around 33-3800rpm (torque peak), especially with  boost
upgrades.  "Adj" in your tag line indicates that you have an adj WG spring
preload.  You might have that dialed down a tad too much for the fuel
available.

HTH

Scott