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Discussion Starter #1
Are my o2 sensors causing me to only get 180-200 miles on a full tank in a g3 vulcan? And did they kill my cats?
 

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Which sensors? The upstream or downstream ones?

The upstream HO2S sensors determine the A/F ratio.

The downstream HO2S sensors perform two functions:
1. They make sure that the cats are operating properly.
2. They serve as the baseline for the upstream sensors. Th downstream sensors should detect that the O2 levels are steady. The EEC oscillates the A/F ratio back and forth (rich to lean and back) and then checks the upstream HO2S sensors against the downstream HO2S sensors.


EDIT: I totally forgot to actually answer your question. Yes, they will definately hurt your fuel economy if they are bad.

And for reference, there are four HO2S sensors in all.
 

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Discussion Starter #3
what about a non-functioning downstream o2 sensor killing my cat(s)?
 

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Originally posted by silvapain@Aug 5 2004, 05:31 PM


EDIT: I totally forgot to actually answer your question.  Yes, they will definately hurt your fuel economy if they are bad. 

And for reference, there are four HO2S sensors in all.
Does a 3.8l also have 4 O2 sensors, i was told that bad ones hurts fuel economy , maybe that's why i only avg. 300 kms a tank :icon_cry:
 

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I'm afraid that i don't know. I am much more familiar with the Vulcan and somewhat the Duratec. But here is how you can look for yourself:


The upstream HO2S sensors are usually right on the exhaust manifold, or just below them. Look for a ~3/4" diameter metal cylinder that is threaded into the exhaust piping with a bundle of wires going into it. That's the sensor. There will be one on each bank (side of the engine).

The downstream HO2S sensors are going to be either threaded directly into the cat, or right behind it. They will look almost identical to the upper ones; however, they are NOT the same part numbers, and are not interchangible.
 

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Some O2 sensors are interchangable. A buddy of mine has an Integra, and his are interchangable. I don't know about the Essex though. I'm a Duratec guy, and even then, I don't know a whole lot about the emissions system.

JR
 

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I'm reffering to the Duratec and the Vulcan. The upstream and downstream HO2S sensors on those are not interchangible. I'm fairly positive that the same is for the Essex.
 
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