O2 sensor and high NOx reading
Thread Starter
Instructor
Joined: Feb 2002
Posts: 164
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From: Doylestown PA
O2 sensor and high NOx reading
Emissions failed miserably today. 3700 ppm NOx. I get an intermittent 'check engine' light when the system hits closed-loop (code indicates O2 sensor). The OBD hook-up at my shop said the O2 sensor's only slightly out of range. They feel it's the cat (which could be true 'cause I think its been running extra lean for awhile which could've over heated the cat and burnt it up). The car's got 49K miles on it (not that that means anything on a 20-year-old car).
My question is, could an O2 sensor, which is on the cusp of failing, rocket the NOx levels that high? The HC levels were fine.
Thanks for any insight.
Peace,
Bill
[Modified by twotone82, 2:24 AM 10/4/2002]
My question is, could an O2 sensor, which is on the cusp of failing, rocket the NOx levels that high? The HC levels were fine.
Thanks for any insight.
Peace,
Bill
[Modified by twotone82, 2:24 AM 10/4/2002]
Pro
Joined: Jun 2001
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From: Quebec
Re: O2 sensor and high NOx reading (twotone82)
If I remember my lesson correctly, NOx results of a combustion happening at over (1200 degrees f)(Not sure how much). That's the main reason they put an EGR valve on the engine. It puts exhaust gases in the combustion chamber to cool the temperature in order to reduce the NOx emission. You could check your EGR valve if it operates correctly. Otherwise, a clogged cat produce a lot of heat and maybe enough to transform the exhaust gases in NOx.
Just a tought
Stephan
[Modified by American Boy, 11:49 PM 10/3/2002]
Just a tought
Stephan
[Modified by American Boy, 11:49 PM 10/3/2002]
Le Mans Master
Joined: Nov 2000
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From: Fort Worth TX
St. Jude Donor '06
Father & Son St. Jude Donor '09
Re: O2 sensor and high NOx reading (American Boy)
If I remember my lesson correctly, NOx results of a combustion happening at over (1200 degrees f)(Not sure how much). That's the main reason they put an EGR valve on the engine. It puts exhaust gases in the combustion chamber to cool the temperature in order to reduce the NOx emission. You could check your EGR valve if it operates correctly. Otherwise, a clogged cat produce a lot of heat and maybe enough to transform the exhaust gases in NOx.
Thread Starter
Instructor
Joined: Feb 2002
Posts: 164
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From: Doylestown PA
Re: O2 sensor and high NOx reading (74-Roadster)
Thanks guys. I did perform a routine check on the EGR not too long ago. No vacuum was applied, but I did a diaphram squeeze w/ the engine warm. The pintle seemed to move correctly. Could be carbon deposits. I'm confused. Sometimes I Hate Newer Combustion Engines!!!
Peace
Peace
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Joined: Sep 1999
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From: Wylie TX
Re: O2 sensor and high NOx reading (American Boy)
If I remember my lesson correctly, NOx results of a combustion happening at over (1200 degrees f)(Not sure how much). That's the main reason they put an EGR valve on the engine. It puts exhaust gases in the combustion chamber to cool the temperature in order to reduce the NOx emission.
