Bad Gas mileage, secondary O2 sensor to blame?

CivicEx'00

New Member
(2000 Civic EX coupe EM1 D16Y8)

I recently had a shop look at my car for a distributor problem, but they also commented on my exhaust O2 sensors, and told me that my plugs were fouled because the engine was running rich... my car doesn't have a cat... the owner before me took it out, so I have a CEL for that (P0420)
They replaced my downstream o2 sensor, but the light came back after a few days.

Recently I have noticed I'm burning through a LOT of gas.. fill up twice in a week. You could say I'm slightly heavy footed, but I highly doubt it could contribute so much. I came to attribute this to the fact that my engine could be running rich, and in the higher RPM range it's just dumping in gas.

How do I get around this?

Will tricking my secondary O2 sensor do the trick? (Mechanical or simulator)

Do I NEED to buy a $200 cat?

How do I get my engine to not run so rich, and in turn get better economy?

As always any advice is appreciated

Attached below are pictures from the service writeup:




 
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CivicEx'00

New Member
The 2nd O2 sensor is only for emissions.

Do a full ignition system tune up and then go from there.
I've heard this elsewhere. It's hard to believe the auto shop either didn't know that or straight up lied to me about it affecting performance. But thank you for the quick reply

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XpL0d3r

I had a Civic once.
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I've heard this elsewhere. It's hard to believe the auto shop either didn't know that or straight up lied to me about it affecting performance. But thank you for the quick reply

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Shop probably knew. But they got your money...
 


XpL0d3r

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They should have never sold you a downstream 02 sensor if they knew you didn't have a cat

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You mean OP, not me. And yes, but a sketchy shop can easily make $ on that. So that's likely why they did.
 


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