[urq] Running Rich issue solved!

Louis-Alain Richard larichard at plguide.com
Mon Feb 26 16:08:51 EST 2007


Bravo Mike ! One less to worry about. Now, Keith, a little effort 
please :-)

Mike,
2 questions come to my mind:
- Did you sealed any engine parts (valve cover, water pump, etc.) with 
RTV silicone recently ? The standard silicone was responsible for O2 
sensor failures in the eighties, IIRW.
- Did you test the dead O2 sensor to confirm that it is indeed dead as 
a doornail ? If not, you can do it easily with a propane torch. Read 
this procedure from this site: 
	http://www.gnttype.org/techarea/ecmsensors/O2sensors.html


Testing O2 sensors on the workbench.

       Use a high impedance DC voltmeter as above. Clamp the sensor in a 
vice, or use a plier or vice-grip to hold it. Clamp your negative 
voltmeter lead to the case, and the positive to the output wire. Use a 
propane torch set to high and the inner blue flame tip to heat the 
fluted or perforated area of the sensor. You should see a DC voltage of 
at least 0.6 within 20 seconds. If not, most likely cause is open 
circuit internally or lead fouling. If OK so far, remove from flame. 
You should see a drop to under 0.1 volt within 4 seconds. If not likely 
silicone fouled. If still OK, heat for two full minutes and watch for 
drops in voltage. Sometimes, the internal connections will open up 
under heat. This is the same a loose wire and is a failure. If the 
sensor is OK at this point, and will switch from high to low quickly as 
you move the flame, the sensor is good. Bear in mind that good or bad 
is relative, with port fuel injection needing faster information than 
carbureted systems.

       ANY O2 sensor that will generate 0.9 volts or more when heated, 
show 0.1 volts or less within one second of flame removal, AND pass the 
two minute heat test is good regardless of age. When replacing a 
sensor, don't miss the opportunity to use the test above on the 
replacement. This will calibrate your evaluation skills and save you 
money in the future. There is almost always *no* benefit in replacing 
an oxygen sensor that will pass the test in the first line of this 
paragraph.


Louis-Alain

> Finally figured out my "super rich" running problem. It was the Oxygen
> sensor! I replaced it last year just as a "preventative maintenance" 
> thing, so I
> didn't think it would be bad. Luckily I try and stock extra parts for 
> times
> like  this and I had a new OX sensor. I was ready to replace the 
> injectors and
> the  WUR!. So perhaps if someone else has a rich (or maybe lean) 
> condition, try
> the  ox sensor. It's a bitch to get at too.
>
>


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