I think my o2 sensor's dying.

[LaureltheQueen]

Ever since the turbo swap, the mileage has been slowly but surely going down the shitter. I'm down to about 11mpg. I AM doing only city stop and go driving currently, but it still shouldn't be this bad. I got new plugs that I need to put in still, but if those don't bring it back to around 16 I think I'm gonna try and track down an o2 sensor. That is, unless a wideband o2 sensor would replace a regular one, and you guys can talk me into it. Suggestions?

If it helps at all, things that were changed in september are:
TD05 16G
Perrin DP
AWIC
K&N filter

[Legacy777]

You can't replace the narrow band unless the wideband has a narrow band output to go to the ECU.

Also, going to move this to a tech forum.

[Matt Monson]

Try unplugging your O2 sensor for a tank and see what happens. I ran my wagon for most of the time I owned it without the O2 sensor plugged in. I used to get 16mpg and no CEL, but I also didn't have a 16g or AWIC...

[Fishy]

My turbo gets ASS for mileage too. I wonder if my O2 sensor is getting old and lazy. At last count it was mid-teens on the highway

What do we recommend for a replacement these days? bosch? walker?

[555BCTurbo]

Laurel-

If you have the $$ a WB02 would be the way to go...you can get the Zeitronix setup for $279 for the sensor, brain, and computer cable so you can datalog on a laptop. The brain has a simulated Narrowband output that you run into the ECU...works totally awesome...

Plus the sensors are no more expensive, or even cheaper to replace down the road, at ~$69.

[LaureltheQueen]

That's not so bad. I'm looking at about $160 for a regular 02 sensor, ugh. So expensive!

[sammydafish]

That's not so bad. I'm looking at about $160 for a regular 02 sensor, ugh. So expensive!

3 wire O2 sensors run about $50

[biggreen96]

I asked the techs at the ford stealership I worked at if there was a way to clean up the 02 sensor because I was worried that mine was dying too. The techs I asked all said that unless you are throwing a CEL not to worry, as long as its voltage is still oscilating sp? once warm it should be good.
John checked my apexi turbo timer which also reads O2 voltage and right away said "yeah its fine"

I think the voltage will oscslllateee sp? very slowly or not at all when its dying/dead. Why spend $160 if you dont NEED to.

Im glad I have the ability to talk right to the techs, cause im sure the service writers would try and sell me tons of crap.

[vrg3]

I disagree with your techs.

Even a good oxygen sensor will oscillate only slowly with Legacies using Hitachi engine management. The ECU doesn't update fuel trims as fast as more modern ECUs do. While that does somewhat mitigate the problems caused by slow sensors, it doesn't fully, and does mask a common symptom of a slow sensor.

There are some more insidious ways a sensor can be bad. If it is contaminated with silica (from using room temperature vulcanizing silicone that isn't sensor-safe, or from the engine ingesting silicate-laden coolant) it can read lean but otherwise appear to function correctly. If the contamination is only slight the sensor might even seem to be oscillating correctly even though the ECU is making the mixture rich.

A new 1-wire sensor can cost as little as $20. At least on turbo models, a 1-wire sensor works just fine.

The few wideband setups I have been exposed to all can be used to replace a stock narrowband sensor. What happens is the control unit has a "simulated narrowband" output that you can hook to the ECU to simulate the signal it would have received from the stock sensor.