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Alex Marcuzzi

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Since: Nov 10, 2003
Posts: 36



(Msg. 1) Posted: Fri Nov 05, 2004 11:59 am
Post subject: High NOx and CO reading
Archived from groups: alt>autos>honda (more info?)
I just failed my emission test with high NOx and CO readings on a 1994
Accord. Does anyone have any advice as to what could be causing this high
readings.

Thanks
Alex

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michaeltnull

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Since: Oct 30, 2004
Posts: 1722



(Msg. 2) Posted: Fri Nov 05, 2004 7:14 pm
Post subject: Re: High NOx and CO reading [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
That is an odd combo. Timing and mixture factors usually raise one while
lowering the other.

My suspicion is that the catalytic converter is kaput - assuming it is a 3
stage cat. It is a common cause of high NOx and can certainly produce high
CO by virtue of not breaking each of those down. I mention about the 3-stage
cat because the third stage - when used - is to break down NOx.

Basically, NOx comes from advanced ignition or lean mixture, while CO comes
from rich mixture.

Mike

"Alex Marcuzzi" <amarc RemoveThis @aei.ca> wrote in message
news:418ba23d$1_4@aeinews....
 >I just failed my emission test with high NOx and CO readings on a 1994
 >Accord. Does anyone have any advice as to what could be causing this high
 >readings.
 >
 > Thanks
 > Alex
 ><!-- ~MESSAGE_AFTER~ -->

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Chip Stein

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Since: Jul 07, 2004
Posts: 89



(Msg. 3) Posted: Sat Nov 06, 2004 5:52 pm
Post subject: Re: High NOx and CO reading [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Michael Pardee" <michaeltnull RemoveThis @cybertrails.com> wrote in message news:<Wq2dnbWuk-QOuBHcRVn-2A RemoveThis @sedona.net>...
 > That is an odd combo. Timing and mixture factors usually raise one while
 > lowering the other.
 >
 > My suspicion is that the catalytic converter is kaput - assuming it is a 3
 > stage cat. It is a common cause of high NOx and can certainly produce high
 > CO by virtue of not breaking each of those down. I mention about the 3-stage
 > cat because the third stage - when used - is to break down NOx.
 >
 > Basically, NOx comes from advanced ignition or lean mixture, while CO comes
 > from rich mixture.
 >
 > Mike
 >
 > "Alex Marcuzzi" <amarc RemoveThis @aei.ca> wrote in message
 > news:418ba23d$1_4@aeinews....
  > >I just failed my emission test with high NOx and CO readings on a 1994
  > >Accord. Does anyone have any advice as to what could be causing this high
  > >readings.
  > >
  > > Thanks
  > > Alex
  > >


egr ports are plugged, have to slide hammer out the plugs, clean
the ports and replug.
the egr system is in place to reduce nox, which is caused by
pressure and high temps.
Chip<!-- ~MESSAGE_AFTER~ -->
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michaeltnull

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Since: Oct 30, 2004
Posts: 1722



(Msg. 4) Posted: Sat Nov 06, 2004 10:10 pm
Post subject: Re: High NOx and CO reading [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Chip Stein" <chip.DeleteThis@chipanddebby.com> wrote in message
news:5ddcea74.0411061652.2d0e7981@posting.google.com...
 > "Michael Pardee" <michaeltnull.DeleteThis@cybertrails.com> wrote in message
 > news:<Wq2dnbWuk-QOuBHcRVn-2A.DeleteThis@sedona.net>...
  >> That is an odd combo. Timing and mixture factors usually raise one while
  >> lowering the other.
  >>
  >> My suspicion is that the catalytic converter is kaput - assuming it is a
  >> 3
  >> stage cat. It is a common cause of high NOx and can certainly produce
  >> high
  >> CO by virtue of not breaking each of those down. I mention about the
  >> 3-stage
  >> cat because the third stage - when used - is to break down NOx.
  >>
  >> Basically, NOx comes from advanced ignition or lean mixture, while CO
  >> comes
  >> from rich mixture.
  >>
  >> Mike
  >>
  >> "Alex Marcuzzi" <amarc.DeleteThis@aei.ca> wrote in message
  >> news:418ba23d$1_4@aeinews....
   >> >I just failed my emission test with high NOx and CO readings on a 1994
   >> >Accord. Does anyone have any advice as to what could be causing this
   >> >high
   >> >readings.
   >> >
   >> > Thanks
   >> > Alex
   >> >
 >
 >
 > egr ports are plugged, have to slide hammer out the plugs, clean
 > the ports and replug.
 > the egr system is in place to reduce nox, which is caused by
 > pressure and high temps.
 > Chip

Although that doesn't explain the CO. Still, EGR is cheaper than a cat!

Mike<!-- ~MESSAGE_AFTER~ -->
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rickyspartan1

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Since: Nov 06, 2004
Posts: 6



(Msg. 5) Posted: Mon Nov 08, 2004 2:43 am
Post subject: Re: High NOx and CO reading [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
"Alex Marcuzzi" <amarc RemoveThis @aei.ca> wrote in message news:418ba23d$1_4@aeinews....

 > I just failed my emission test with high NOx and readings on a 1994
 > Accord. Does anyone have any advice as to what could be causing this high
 > readings. Thanks Alex

CO is high, could be an inoperative O2 sensor. NOx is high, could
be an inoperative EGR valve, carbon deposits, over advanced timing,
cooling system too hot, lean mixture, cat-converter, or any mixture of
the above. An inoperative O2 sensor could have worn out the cat-
converter.<!-- ~MESSAGE_AFTER~ -->
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