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Help me diagnose my o2 readings

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blackrosenova40

15+ Year Contributor
398
3
Jan 12, 2006
Belle Plaine, Minnesota
Well for quite some time my 1990 eclipse hasnt used an o2 sensor. A long story in itself but I installed a used one back in and I had to rewire the sensor.

After the rewire and installing the o2 sensor my o2 readings are barely coming off very lean so im assuming it is bad.

Another thing I noticed is that it doesnt cycle back and forth like a normal narrow band sensor does when its not under load.

My question is, if the sensor is bad, should it still swing back and forth on my gauge or is there something else wrong besides my o2 sensor, if it is bad at all.
 
If the sensor is new, check your timing. If the CAS is set too far advanced, it'll give the same readings as a dead O2 sensor.
 
Nope its not a new o2 sensor.

Is my air/fuel gauge supposed to cycle back and forth when its not under load, even with a bad o2 sensor?

The reason I ask is that im 95% sure I wired it back in correctly, but it has been unhooked for so long I want to make sure it never shorted and fried a part of the ecu somehow.
 
Is it a standard 50 dollar a/f gauge with a stock o2 sensor? If so, it will always be nothing more than a light show. Our cars need a wideband setup to be worth their salt. I would look into a pyrometer if you want to tune, it will give you much more useable results than your a/f. Hot=lean, cold=rich
 
Dude I need the o2 sensor to work right otherwise my car will always be in limp mode and its getting old having my cel light on.

Will the a/f gauge cycle if the o2 sensor is bad?

I understand using a wideband is far far more accurate and I plan on it in the near future but I want to fix this first since my gas mileage is hideous.
 
Is it a standard 50 dollar a/f gauge with a stock o2 sensor? If so, it will always be nothing more than a light show. Our cars need a wideband setup to be worth their salt. I would look into a pyrometer if you want to tune, it will give you much more useable results than your a/f. Hot=lean, cold=rich

You forgot one too rich=hot again You need a wide band also the EGT is a useful tool but its readings can be misinterpreted with out some reference to the A/F/ ratio.
 
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