How can I test my oxygen sensor?

[Decolliber]

How can you tell if an O2 sensor is working properly? I tried unplugging mine after engine had reached operating temperature, expecting that I would notice a change in idle (higher, because mixture would go rich?), but there was no change in the idle. (The idle is actually a bit high anyway, at about 1000, because I just installed a Dansk premuffler and a Steve W chip, and have been gradually adjusting the idle back down to 880).
This is a brand new O2 sensor, so I am wondering if something is wrong with it. Is there any easy way for me to test the sensor, such as checking voltage at the plug?

[Tinker]

See if this helps: http://home.flash.net/~lorint/lorin/fuel/oxybench.htm

Tinker

[Lorenfb]

You might want to ask your chip supplier why your idle is too high.
Did he advance the ignition timing too far? You shouldn't have to foul
with the idle setting. If the chip is working properly, the idle control
circuitry should keep the idle at the correct value.

"How can you tell if an O2 sensor is working properly? I tried unplugging mine after engine had reached operating temperature, expecting that I would notice a change in idle (higher, because mixture would go rich?), but there was no change in the idle."

Could it be that the chip has the O2 sensor disabled to achieve more performance?
A working O2 sensor on a 3.2 is VERY noticeable at idle.

[jpahemi]

I was told removing the O2 with a modified chip will yield substantial HP increase, like the the Euro 3.2 with 231.
Regards,
J.P.

[Early_S_Man]

To test the sensor you need a high-impedance DC Voltmeter [10 MegOhms or greater input impedance] or multimeter. You need to use the 'test port' connection and be ABSOLUTELY SURE there is no chance of shorting out the sensor leads!!!

When fully warmed-up to operating temperature and connected to the ECU ... the Voltage should vary on both sides of stoich., i, e., 0.2 - 0.3 Volts to 0.8 - 0.9 Volts ate a fairly slow rate ... 2 to 5 times per second. An oscilloscope with high-impedance 10:1 probe can also be used to monitor the Voltage fluctuation.

[rzepko6194]

Originally posted by Lorenfb
Could it be that the chip has the O2 sensor disabled to achieve more performance?
A working O2 sensor on a 3.2 is VERY noticeable at idle.

Yeah, and coupled with a stock chip the idle is pretty crappy.

Decolliber, email Steve Wong directly, I sure he'll be able to answer your question.

[ausgezeichnet]

When you are testing make sure your are testing the correct wires. You probally have a 3 wire O2 sensor. If so, the two white wires are power to the heater circut and ground. The Black wire is the signal wire.

[Decolliber]

Thanks for all the interesting and helkpful responses. I did email Steve W and got a quick reponse. He tells me that if everything is adjusted properly, that the idle should not change when the O2 sensor is unplugged. Nevertheless, I will test the O2 sensor. If I am understanding correctly, I would connect the multimeter to the black wire and to the ground and look for a voltage fluctuation between 0.2 and -0.7 volts?

[scarceller]

Originally posted by Early_S_Man
To test the sensor you need a high-impedance DC Voltmeter [10 MegOhms or greater input impedance] or multimeter. You need to use the 'test port' connection and be ABSOLUTELY SURE there is no chance of shorting out the sensor leads!!!

When fully warmed-up to operating temperature and connected to the ECU ... the Voltage should vary on both sides of stoich., i, e., 0.2 - 0.3 Volts to 0.8 - 0.9 Volts ate a fairly slow rate ... 2 to 5 times per second. An oscilloscope with high-impedance 10:1 probe can also be used to monitor the Voltage fluctuation.

I have an 84 Carrera 3.2L and I have scoped my O2 sensor at idle and see .3V to .8V swing on the o-scope but it swings only 1 cycle per second. In otherwords, it takes 1 second to go from .3V to .8V then back down to .3V then it repeates this cycle every second. Also, it looks like it misses a cycle or 2 every so often at idle but at 2000RPM the cycles are constant at about 1 per second.

What does it mean when it responds slow? BAD O2?

Thanks.