02 testing

[philipk65]

What should the time intervals be between switching voltage?

How do I create a rich mixture for checking the 02 sensor high reading?

[MT-2500]

What year and engine?
What are you reading or testing them with?
MT

[philipk65]

'91 4.3 L

I'm testing with a digital ohm/voltmeter.

[MT-2500]

Originally Posted by philipk65

'91 4.3 L

I'm testing with a digital ohm/voltmeter.

That one is a slow 02 sensor switching system.
With engine up to full tempt and on the road testing.
The 02 sensor should switch over and under .5 volts within a minute.
If over 2 minutes it will set a code.

At idle setting still a lot of them systems will drop out of closed loop.
The sensor has to be keep hot and at full engine tempt to work.

Pump the gas or pull map sensor vacuum and or unplug tempt sensor and you should see rich on 02 sensor.
Pull PCV valve and you should see lean on 02 sensor.

If not much switching under and over .5 volts and.
If the senor is old and never been changed you can put on a new one for 29.95 US $.

Are you having any engine running problems or codes or just checking 02 sensor?
MT

[MT-2500]

Originally Posted by philipk65

'91 4.3 L

I'm testing with a digital ohm/voltmeter.

On any sensor testing you need to use a Low impendence volt/ohm meter.
The old resistor type will not read light computer voltage good and can even damage pcm.
MT

[philipk65]

MT-2500, No codes and the vehicle runs fine, but I need it to pass smog so I'm checking everything. I wanted to check out to 02 sensor first, because to get this one out is going to be a chore!

I have a $50 digital volt/ohm meter. Is that low impedence? How do I check?

[MT-2500]

Originally Posted by philipk65

MT-2500, No codes and the vehicle runs fine, but I need it to pass smog so I'm checking everything. I wanted to check out to 02 sensor first, because to get this one out is going to be a chore!

I have a $50 digital volt/ohm meter. Is that low impedence? How do I check?

Hook it into 02 sensor wire and warm engine up good and read voltage.
Watch for switching over and under .5 volts.

[philipk65]

MT-2500, I hooked up the digital ohm/volt meter to the 02 sensor and took it on the road and I got readings from - .20 - .92 volts. Switching back and forth everycouple of seconds.

[MT-2500]

Originally Posted by philipk65

MT-2500, I hooked up the digital ohm/volt meter to the 02 sensor and took it on the road and I got readings from - .20 - .92 volts. Switching back and forth everycouple of seconds.

It is working good.
Go ahead and have them do the emissions test.
If anything is not good it will show up on emission testing.
Good luck
If it is the 02 that came on it it could be a dirty or little weak or/off on 02 readings but still switching good.
If much off a good missions test will pick up on it.
I would make sure the plugs and wires and filters and base timing is good are good
MT