Wide Band O2 sensor response to missfire 3

[patprimmer]

In another site we have a debate going on about a miss fire where a rich mixture suddenly shows lean on a wide band as it loses power for a short interval then shows rich again as it regains power.

This is during a dyno tune on a Honda with a roots blower.

They are trying to decide if it is momentary spark breakdown or a hiccup in the fuel map. The map shows no abnormalities on the laptop.

Does completely unburned fuel show rich or lean on a wide band oxygen sensor.

Regards
Pat
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[MacGyverS2000]

Pat,

Since an O2 sensor is essentially comparing the amount of O2 on two sides of a diaphragm (one side in the exhaust stream, the other in the outside environment), you could theoretically shove a baby down the tailpipe and it wouldn't effect the sensor's reading. Bring in a bunch of air, squirt fuel into it, but forget to ignite the fuel, the O2 ratio is going to look (nearly) like 1:1...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[DRWeig]

...you could theoretically shove a baby down the tailpipe and it wouldn't effect the sensor's reading.

OK, I didn't think I was going to smile all day -- so thanks for turning it around!!

By the way, Pat, I agree that it'll momentarily spike up showing really lean if you don't use any of the oxygen because of a misfire. The sensor responds really fast, but I'm not sure how the engine controller will handle it.

Good on y'all,

Goober Dave

 

[mattsooty]

Pat,

Both guys are correct, the reading will show a lean spike.

MS

 

[patprimmer]

Thanks guys. That makes sense.

Regards
Pat
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