Well, got a DMM and measured the output voltage from both sensors.
Nil, zero, zip, nothing. BOTH sensors read nothing. Why?
My Ford (sorry :-) fuel injection book says "the sensor is a dependable
unit. Occasionally it will fail with an internal open circuit. The most
common problem that occurs with EGO [exhaust gas oxygen] sensors is
contamination. Three common sources...are RTV silicone, tetraethyl lead,
and soot."
(1) RTV contamination manifests itself after the fumes coat the sensor
and result in the sensor reacting *really* slow to changes in the
exhaust. Usually results in a lean (low voltage) signal from the sensor.
(2) Leaded fuel contamination will cause the sensor to continually read a
rich (high voltage) condition.
(3) Oil and fuel soot from worn rings or valve guides or rich running
engines will also coat the sensor(s) and fixes the output voltage at a
constant 500 mV or so.
Since BOTH my sensors seem bad, and the output is nearly zero, I'd have to
suspect (1). However, the only RTV silicone I've used on my car is
Permatex Ultra Copper which very clearly says "sensor safe" right on the
package. I'll be really mad if the stuff ISN'T sensor safe. Could the
anti-seize I put on the threads mess up the sensors? Anyway, the sensors
both act like there's a short in the sensor wiring. Wiggling the wires
makes the voltage jump around wildly (kind of hard to tell with a digital
voltmeter). Maybe I wasn't careful with the wires last time I took them
out (I recently dropped the exhaust to remove my starter) and they cracked
or the wire inside broke. I'll do an autopsy (good word!) on them when I
take them out. GRRRR. Those silly things are $40 each too!
Anyway, that's what's wrong with the car. Meantime, has anyone checked to
see if we can buy the bar graph display and driver chip at Radio Shack?
:-) :-)
jim
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