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Discussion Starter #1
what does this mean on an emissions test.

not the taurus but the nissan failed with a reading of 6.45 state allows 3.25
here are the other readings:
HC GPM .70
CO GPM 7.85
NOX GPM 6.45
CO2 579.31

Any ideas where to start?
bryan
 

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Are you showing any codes? The O2 sensors should register as being bad, as should the cats.

The likely issue is that the upstream O2 sensors are bad, which is screwing up the A/F mixture, and it's running rich. When that happens, the cat degrades over time, though the downstream cat is supposed to measure the catalyst efficiency.

How many miles are on the Nissan?

JR
 

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IIRC, GPM is Gallons Per Minute.
 

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Discussion Starter #6
Are you showing any codes? The O2 sensors should register as being bad, as should the cats.

The likely issue is that the upstream O2 sensors are bad, which is screwing up the A/F mixture, and it's running rich. When that happens, the cat degrades over time, though the downstream cat is supposed to measure the catalyst efficiency.

How many miles are on the Nissan?

JR
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151g on the nissan. the cel just came on a month ago. after 15 years.
the problem is obd1 so i can't goto az to get it read. the other option is the computer has
a diagnostic mode but to get to it i have to take panels off on the center console. not feeling that right now
especially when the temp is 2 degrees. :( i have heard their is a paper clip trick to get the light to flash
but have not found the steps for it.

ri you have to have test every two years so it passed two years ago on first try.
can the cats degrade without the cel on and it passing until now.

from what haynes says there is one o2 sensor.
bryan
 

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There won't be a downstream O2 sensor measuring the catalytic converter efficiency on an OBD-I car. If the Nissan is a 4-cyl car, there will be only one O2 sensor.

NOx means Nitrogen Oxides - Caused by high cylinder temps. It can be from a bad EGR system, poor cooling system, too hot spark plugs, and also a failed cat. NOx emissions won't come from running rich, as running rich causes low cylinder temps.

High CO emissions comes from the engine running too rich


EDIT: I believe GPM means Grams Per Minute, but I'm not sure.
 

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Discussion Starter #8
There won't be a downstream O2 sensor measuring the catalytic converter efficiency on an OBD-I car. If the Nissan is a 4-cyl car, there will be only one O2 sensor.

NOx means Nitrogen Oxides - Caused by high cylinder temps. It can be from a bad EGR system, poor cooling system, too hot spark plugs, and also a failed cat. NOx emissions won't come from running rich, as running rich causes low cylinder temps.

High CO emissions comes from the engine running too rich


EDIT: I believe GPM means Grams Per Minute, but I'm not sure.
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thanks daniel, so o2 is out of the equation.
from the manual the egr is under the intake and not easily reached.
poor cooling system the water pump is ok not leaking but not sure when the last coolant flush
has been done.
just did a tune up, ngk plugs with new wires and rotor.
 

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Discussion Starter #10
Step one would be finding out what that code is.
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read the code today. not bad to do except for the snow. :lol2:

code 32 came up, which nissan forum says egr function.

what should my next step be.

should i run and get it inspected while the cel is off?
 

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NOx is a EGR problem. If the EGR is working properly then the cats are the problem. Some cats are specifically made to take care of NOx. Usually it is a three way cat.

Nothing to do with the O2s.
 

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I know you can fail if you don't make sure the vehicle is WELL heated up before you get it tested. As in drive it on the highway AT LEAST 15 minutes before doing the test. Also running a can of Seafoam through it could help as well. If it does have a messed up EGR that could also cause it so I'd fix that as well. Another thing that can help is waiting until you are down to about 1-2 gallons of fuel and adding about 3 oz of 100% acetone to the tank along with a FULL container of 91% or better alcohol to the system. It worked for a friend of mine.
 

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Discussion Starter #14
Decarbonize the engine and intake tract. Toyotas and Nissans used to be, fairly bad about that.
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i imagine decarbonizing is the same thing i was told about the egr with carbon build up.
but i've gotten two different stories how to get to the egr. the haynes says yopu have to go from underneath
to get the pipe off from the bottom of the valve. everyone else no to the best of their knowledge
its all from the top.

the nissan FSM is confusing too since it's an online version and mainly goes through testing it but nothing from
what i can tell to replacing.



NOx is a EGR problem. If the EGR is working properly then the cats are the problem. Some cats are specifically made to take care of NOx. Usually it is a three way cat.

Nothing to do with the O2s.
[/b]
i double checked the o2s with the on board cpu and it checked out.
 

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Discussion Starter #15
:banana: i know the people that helped me with this problem are light years ahead of my
mechanics skill but i did it myself installed the new egr and put everything back together.

surprisingly i had no extra parts. :lol2:

i kept spraying pb blaster on the bolts and the jy find to make my life easier.
now i just need to drive it and see if the code comes back and get it inspected.
 
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