Replacing the O2 sensor...

takza · Post by **takza** » Mon Aug 30, 2004 5:46 pm

With my '83 wagon, the O2 sensor was looking rather poor....rusted and so forth. Could have tested it with a voltmeter...but I just went ahead and replaced it.

Mainly because replacing the one in my other car resulted in an 9-10% gain in MPG.

Found one at AdvanceAP:

Bosch 2031 Oxygen Sensor: Single Wire $29.98

Check/Replace Interval 50K Miles; Universal Type w/o Connector; 1 Wire; Unheated

It's best to try and get to it from underneath the car...and even then it's a little hard to get to. I put PBBlaster on the 2 bolts holding it several times over 24 hrs before the actual removal.

After the bolts were out...I then needed to disconnect the connector...the release on this does not work the way you might think it would..try the opposite way.

After the old sensor is out, you will need to cut the old wire in order to reuse the old connector (keep as much wire length as you can). I crimped the wires and then soldered the connxs. There is some shrink tubing supplied to cover this splice.

Then you need to clean off the old gasket from the manifold. I used some copper anti-seize on the studs before putting the new sensor on...VERY important to keep this stuff OFF the end of the sensor.

Results?

* I enabled the EGR again and found that the new O2 sensor caused the EGR to make the car buck from idle up to around 1500 RPM to the point where the car was undrivable...then I disabled it again. Probably a defective "gizmo" somewhere under the hood...maybe the vac modulator...which on my car didn't test out all that well.

The car had run just fine before with the EGR enabled....though there was a loss of power and MPG.

* After shutting down the EGR, the car now runs real well...no noticable loss of power...and it will idle pretty well down to 500-600 RPM (need to set this back up to 700-800).

* the idle was improved previously by snugging down most of the 9 manifold bolts...about 1/2 of them being loose.

>> Will check the mileage after running thru one tank...and it's possible there will be some gain.

<span style='color:blue'>Found no mileage gain from installing the O2 sensor.</span>

Lateer · Post by **Lateer** » Mon Aug 30, 2004 10:38 pm

What aspiration system for the '83 Tercel has an O2 sensor?
I've not seen anything like that on mine, which has the 3A-C engine...

takza · Post by **takza** » Tue Aug 31, 2004 2:39 am

1983 <span style='color:blue'>*KAL-EYE-PHORN-EAAAH*</span> model.......not sure what other 3AC engines had them.

Lateer · Post by **Lateer** » Wed Sep 01, 2004 7:06 pm

Ah. Sorry.

I was under the impression that the C in 3A-C meant the Califonrian emissions control measures, which include an O2 sensor.

It's just I've never seen one on my machine, and I've been looking since you mentioned it.

takza · Post by **takza** » Thu Sep 02, 2004 8:00 pm

Finally got to check the mileage with the new O2 sensor.....NO CHANGE from recent average.

But....there were 4 different things changed for this tank of gas....new roof rack (greater wind resistance)...new trans/diff oils (?)...timing set back to 12 BTDC (?)...new O2 sensor.

So hard to say what the O2 sensor did for the mileage....does make the car idle better (without the EGR) and it has good power and runs good.

Lateer · Post by **Lateer** » Thu Sep 02, 2004 10:36 pm

Takza,

Where was the O2 sensor mounted?

I'm thinking about putting in an aftermarket oxygen gauge, something like a Halmeter AF30, to monitor the air/fuel mixtures of my Weber as the various circuits within it come into line.

It'd make my life easier if there was already a drilled and tapped hole in the exhaust manifold for me to use...

Thanks.

takza · Post by **takza** » Fri Sep 03, 2004 5:19 am

As I remember, it's bolted into a flange situated towards the front right before the manifold goes into the downpipe.

For what you want...since this car has a double-walled downpipe, maybe insert that gauge in the single-walled pipe right before the convertor if you have one?