93 3.0 O2 sensor question.

[dniksch]

Should I go with a Ford O2 sensor/s or aftermarket ok and if so which ones are best. I did a search on here for this question and didnt find an answer for me. Thanks for the help.

 

[locovaca]

I use Bosch, never had an issue.

 

[pillen140]

Some bosch stuff sucks, but they're usually the best you'll find at an aftermarket parts store. If you go through ford you pay double probably though.

 

[BRUTUS_T_HOG]

bosch, delphi, ntk, denso- good aftermarket brands

 

[locovaca]

Some bosch stuff sucks, but they're usually the best you'll find at an aftermarket parts store. If you go through ford you pay double probably though.

Bosch has crap spark plugs, but they invented the O2 sensor. They're the best aftermarket brand O2 sensor you can buy as far as I'm concerned.

 

[helpme]

94 3.0 O2 sensor wiring

I wanted to test and see if my O2 sensor was working properly.
Have had trouble with high NOx. Engine does not have EGR valve. I wanted to measure the output with a voltmeter.
What wire do you monitor for that? It has 4 wires coming out of it. 2 white wires (preheater?), a black wire and a gray wire.
Its a 94 with over 200K on it and so far as I know the O2 sensors have never been changed (or even cleaned). Bought vehicle new.
Many thanks.

 

[Rearanger]

http://www.youtube.com/watch?v=vdn4Dk5PSwc

Frankly, at 200k I would just replace it.

 

[helpme]

Thanks Rearanger

Good point. But I hate to throw money at it if it won't help me pass emmissions in January.
Put a new cat on it 2 yrs ago and a year later (last year) it wouldn't pass again (same problem- high NOx). Had to pay some Mexicans $180 to "fudge it through". I was desparate-only had two weeks left. And I HATE doing business with Mexicans.
But I know I can put a new cat on it and it will pass.
Thanks.

 

[locovaca]

The expected service life on O2 sensors is around 60-80k miles. They're three times past due to be replaced, I wouldn't call it throwing money at it.

 

[BRUTUS_T_HOG]

I wanted to test and see if my O2 sensor was working properly.
Have had trouble with high NOx. Engine does not have EGR valve. I wanted to measure the output with a voltmeter.
What wire do you monitor for that? It has 4 wires coming out of it. 2 white wires (preheater?), a black wire and a gray wire.
Its a 94 with over 200K on it and so far as I know the O2 sensors have never been changed (or even cleaned). Bought vehicle new.
Many thanks.

grey wire. test with the engine hot. hold the rpms at about 2500 for a few minutes and check that the O2 sensors fluctuate between 0.2V and 0.8V

then wait till the voltage is low and rap the throttle. if the voltage doesn't instantly jump up to 0.9V then that O2 sensor is lazy and needs to be replaced.

most cheap meters don't have a fast enough refresh rate to keep up with the voltage changes though.

at 200k miles your O2 sensors are no doubt performing less than optimal. just replace them all.

also O2 sensors won't help with nox, but will help with everything else.

 

[helpme]

Thanks all.

High NOx is my problem. I was told that an underperforming O2 sensor will make it run rich thereby creating a high NOx problem.
I found elsewhere on the net it said black was the signal wire. But it makes sense that might be ground.
I have an analog voltmeter which should give faster response times than a digital.
Now, to change them do you cut the wires and splice? Looks like the connector is between the heads and the firewall and is difficult to get to.
Or do you unscrew the sensor (coiling up the wires) and then unplug after you've got it out of the pipe?
Thanks again.

 

[locovaca]

High NOx is my problem. I was told that an underperforming O2 sensor will make it run rich thereby creating a high NOx problem.
I found elsewhere on the net it said black was the signal wire. But it makes sense that might be ground.
I have an analog voltmeter which should give faster response times than a digital.
Now, to change them do you cut the wires and splice? Looks like the connector is between the heads and the firewall and is difficult to get to.
Or do you unscrew the sensor (coiling up the wires) and then unplug after you've got it out of the pipe?
Thanks again.

Unplug and unscrew, usually in that order. They make O2 Sensor sockets for cheap, that will save you a ton of heartache from trying to get a wrench around it. The connector is difficult to reach but it's doable.

 

[BRUTUS_T_HOG]

NOX is caused by combustion temperatures in excess of 2500*F. usually caused by running lean or overly advanced ignition timing.

high compression from carbon deposits could also cause excess NOX.

the EGR valve reduces NOX, but since you don't have one have you adjusted your timing recently?

 

[helpme]

Bouncing up and down...

between .22 and .98 cold and even after warmed up. Should it stabilize out at some point?
The black wire is the signal wire. Gray rings to ground.

 

[BRUTUS_T_HOG]

it should continuously switch from high to low. sounds like they are working just fine.

but you have to be sure they have an instant reaction time