NOx failures

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NOx failures

Evaponly818
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Re: NOx failures

tampered
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I had one of these once or very close to one of these but anyways, same symptom and my inexperienced ass was chasing its tail big time.  Hollow CAT, turned out to be.  I'm sure someone here can point you in a much more likely direction.

Now that I think about it, mine had EGR.

The only thing about wearing a mask that bothers me is that the girls are a lot friendlier.
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Re: NOx failures

Evaponly818
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Re: NOx failures

Moderator
In reply to this post by Evaponly818
We're not required to check base timing on those, but check it anyway, and see if the distributor is cranked to near the edge of the slot.

Does the VIR show unusually high O2 or unusually low CO?  Can you give us Lambda?

Are the HCs above average?

Is there a way you can get access to Mode $06?
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Re: NOx failures

smog frogposter
In reply to this post by Evaponly818
Evaponly818 wrote
A guy I know took his 96 Honda Civic 1.6L (did not bring it to me) and failed for NOx in 15mph. I’m going based off the picture he sent me of his VIR and it says no EGR under visual(I do not have the car here so I can’t confirm if it has it or not). My question is when a vehicle fails for NOx what are possible causes? If the car has no egr
Check the feedback system from the lambda sensor and verify it is not sending a biased signal, or if there is an exhaust leak  before the catalyst. The Rhodium bed in a TWC requires a slightly richer A/F mixture to properly strip oxides of nitrogen and a biased feedback sensor or an exhaust leak in the upstream exhaust may contribute to high NOX. Carbon build up inside the cylinders also contribute to higher than normal NOX, overtime these carbon deposits get so bad it may actually increase the compression ratio increasing temperatures therefore increasing NOX. Verify proper cooling system operation, higher temperatures contribute to higher NOX levels.
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Re: NOx failures

Troll
In reply to this post by Evaponly818
Come on dude-
Smog class hammered that scenaraio.
That's actually smog 101.
Good luck
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Re: NOx failures

Juicebox
In reply to this post by Evaponly818
Lazy front o2 or cracked manifold, super common on those civics with the manifold cat. The o2 doesn't have to be biased to cause high nox, if the switch rate is too slow the cat cant reduce nox emissions.
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Re: NOx failures

Moderator
Agreed.
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Re: NOx failures

dcf1ver
In reply to this post by Troll
Troll wrote
Come on dude-
Smog class hammered that scenaraio.
That's actually smog 101.
Good luck
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Re: NOx failures

BayAreaSmogTech
In reply to this post by Evaponly818
Evaponly818 wrote
A guy I know took his 96 Honda Civic 1.6L (did not bring it to me) and failed for NOx in 15mph. I’m going based off the picture he sent me of his VIR and it says no EGR under visual(I do not have the car here so I can’t confirm if it has it or not). My question is when a vehicle fails for NOx what are possible causes? If the car has no egr
Lack of coolant, overheating, advanced timing, bad oxygen sensor, exhaust leak pre cat, wrong motor/high compression. The list goes on and on.
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Re: NOx failures

Kevin
In reply to this post by Evaponly818
A vehicle with bad internal timing can also have nox issues

On Mon, Mar 9, 2020, 3:29 PM Evaponly818 [via Stop The Star Program] <[hidden email]> wrote:
A guy I know took his 96 Honda Civic 1.6L (did not bring it to me) and failed for NOx in 15mph. I’m going based off the picture he sent me of his VIR and it says no EGR under visual(I do not have the car here so I can’t confirm if it has it or not). My question is when a vehicle fails for NOx what are possible causes? If the car has no egr


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Re: NOx failures

No One
In reply to this post by Evaponly818
Evaponly818 wrote
A guy I know took his 96 Honda Civic 1.6L (did not bring it to me) and failed for NOx in 15mph. I’m going based off the picture he sent me of his VIR and it says no EGR under visual(I do not have the car here so I can’t confirm if it has it or not). My question is when a vehicle fails for NOx what are possible causes? If the car has no egr
Who scared my boi evap away? I liked his questions.