At 09:25 PM 11/2/01 -0500, you wrote:
>--SNIP--
>Big sale at Sears this weekend, I think Andy's buying a new toy :) Are
>the specs
>for the O2 sensor test in the FSM? andy
Andy
I think that I wrote a digital voltmeter before. I meant to write Digital
Multi-Meter
or Digital Volt-Ohm Meter. Hope that is included in the Sears sale.
The most straightforward test of a typical oxygen sensor is to
unplug its lead, attach a digital VOM to the pigtail, and read voltage
output. Don't use an analog meter because it won't have enough impedance
to insure against blowing something. Also, with electrically-heated sensors
make sure you use the signal output wire, which is usually color-coded black.
Check your FSM.
With the engine warmed up (the sensor has to reach 600 deg. F.
before it starts working, see what your meter displays. You should
see something between .1V and .9V. Zero volts is a sure sign of
a dead sensor.
Next, cause a rich condition for a moment by blocking the air cleaner's inlets
or pulling the CTS (Coolant Temperature Sensor) lead. The reading should
rise rapidly. Pull a vacuum line (e.g. one from the pcv valve) to produce lean
running, and the meter should show falling voltage.
You can also leave the sensor's lead attached to the harness, and
probe the connector with your meter to find out what the system's
up to. Voltage should vary rapidly and continually. The rule of
thumb is ten trips across the rich/lean line of 450 mV every ten
seconds. This is basically what an afr gauge does.
HTH. Bob
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