Failed emissions -- NOx
12-03-2003, 03:27 PM
#1
Failed emissions -- NOx
I failed emissions today 
I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
12-03-2003, 03:36 PM
#2
Originally Posted by Mizeree_X
I failed emissions today I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.Buy my new EGR for sale
12-03-2003, 03:38 PM
#3
I'm a newbie at emissions stuff, but just thinking about the whole NOx are created when combustion temperature gets too high... whens the last time you flushed your coolant? (i dont know if that will work or not) but also what about spark plugs?
Doesnt the EGR control NOx?
Again, I'm a emissions newbie
Doesnt the EGR control NOx?
Again, I'm a emissions newbie
12-03-2003, 03:56 PM
#5
I've been working with another guy on this to pass his inspection here in TX.. Same problem- high NOx reading on one trip, then on the retest he's got good NOx, but high HC and CO...
He already replaced his EGR, and it didn't make a difference (evidently his old one was functional)...
do a google search on 'High NOx emission' or something like that. I found several good pages that talk about it and list things to do to try to fix the problem.
He already replaced his EGR, and it didn't make a difference (evidently his old one was functional)...
do a google search on 'High NOx emission' or something like that. I found several good pages that talk about it and list things to do to try to fix the problem.
12-03-2003, 04:09 PM
#6
Send me your wheels and we'll talk. 
I'm reading this now.
http://www.wivip.com/3_5_1.PDF
I'm reading this now.
http://www.wivip.com/3_5_1.PDF
Originally Posted by Mizeree_X
I failed emissions today I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
)
12-03-2003, 05:24 PM
#9
Originally Posted by Mizeree_X
I failed emissions today I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.
I had already failed once, but the car had only been warm for about 10-15 minutes and my EGR valve was looking pretty dirty so I chalked it up to that. I cleaned my EGR valve, and drove for 40 minutes before testing. My hydrocarbons and CO levels were much lower this time, but my NOx levels actually increased! I noticed that my NOx levels seem to mirror my CO2 levels, as I have printouts showing them during the speed test (the car is put on rollers, driven to a certain speed, then slowed down). The low HC and CO levels tell me that I am burning fuel pretty efficiently, and am not running too rich (or at least that's my analysis). From what I remember about combustion from thermo, NOx are created when the combustion temperature gets too high. Should I replace my coolant temp sensor maybe? I am probly gonna get a new cat too, though I don't know how mine got poisoned in the first place. I am pretty stumped here, as I didn't expect this car to fail emissions at all. Any advice you could me would be great.You don't need the cat.
the cat is there to dispose of the unburnt fuel.
IIRC NOx levels are elevated because of a lean condition.
So that too could be caused by a faulty o2 but I doubt it (never seen an o2 cause it before)
Pull your plugs and look at them.
http://www.motocross.com/motoprof/mo...lug2/plug2.htm
Read that little tidbit for more info on reading your plugs and how to correct it.
BTW have you changed plugs since your last emission test?
12-03-2003, 05:29 PM
#10
Alright, I've been reading on this a little and it has been encouraging and disappointing at the same time. It looks like the EGR system is the main culprit for high NOx emissions, while the cat is in the middle of the hierarchy to check. I know my EGR valve opens, because I've checked, but maybe one of the components that controls is is bust. Consulting my trusty FSM, I guess I need to check the EGRC-solenoid valve, the EGR temp sensor, and EGR tube. Also, the EGR is controlled by signals from the TPS and coolant temp sensor. Sooo, it looks like its time to locate some sensors and bust out the ol' multimeter. Fun times. Thanks for all your advice guys, its been great.
[edit] Internetautomar, my plugs are less than 10k old but I suppose that one or more of them aren't firing all the time. Argghh. Time to play mechanic. [/edit]
[edit] Internetautomar, my plugs are less than 10k old but I suppose that one or more of them aren't firing all the time. Argghh. Time to play mechanic.
[/edit]
12-04-2003, 07:09 AM
#12
Originally Posted by internetautomar
I'm shooting myself in the foot by saying this but,
You don't need the cat.
the cat is there to dispose of the unburnt fuel.
IIRC NOx levels are elevated because of a lean condition.
So that too could be caused by a faulty o2 but I doubt it (never seen an o2 cause it before)
Pull your plugs and look at them.
http://www.motocross.com/motoprof/mo...lug2/plug2.htm
Read that little tidbit for more info on reading your plugs and how to correct it.
BTW have you changed plugs since your last emission test?
You don't need the cat.
the cat is there to dispose of the unburnt fuel.
IIRC NOx levels are elevated because of a lean condition.
So that too could be caused by a faulty o2 but I doubt it (never seen an o2 cause it before)
Pull your plugs and look at them.
http://www.motocross.com/motoprof/mo...lug2/plug2.htm
Read that little tidbit for more info on reading your plugs and how to correct it.
BTW have you changed plugs since your last emission test?
12-04-2003, 07:22 AM
#13
NO emissions is mainly controlled by the cat.
I'd reccomend getting a can of liquid Sea Foam, and let the intake slowly suck it in while the enigine is idling (follow the directions).
If you cannot find sea foam, then use regular carb cleaner, unplug one of the vacuum lines running into the intake manifold and spray into the manifold. You can use the whole can (follow the directions).
Both methods will help clean your cat. I've done this before and my emissions are NEARLY ZERO (as good as new!).
Your cat is probably not spoiled, it just aquires a lot of carbon deposits over time making it less efficient.
I'd reccomend getting a can of liquid Sea Foam, and let the intake slowly suck it in while the enigine is idling (follow the directions).
If you cannot find sea foam, then use regular carb cleaner, unplug one of the vacuum lines running into the intake manifold and spray into the manifold. You can use the whole can (follow the directions).
Both methods will help clean your cat. I've done this before and my emissions are NEARLY ZERO (as good as new!).
Your cat is probably not spoiled, it just aquires a lot of carbon deposits over time making it less efficient.
12-04-2003, 07:34 AM
#14
Originally Posted by eric93SE
NO emissions is mainly controlled by the cat.
I'd reccomend getting a can of liquid Sea Foam, and let the intake slowly suck it in while the enigine is idling (follow the directions).
If you cannot find sea foam, then use regular carb cleaner, unplug one of the vacuum lines running into the intake manifold and spray into the manifold. You can use the whole can (follow the directions).
Both methods will help clean your cat. I've done this before and my emissions are NEARLY ZERO (as good as new!).
Your cat is probably not spoiled, it just aquires a lot of carbon deposits over time making it less efficient.
I'd reccomend getting a can of liquid Sea Foam, and let the intake slowly suck it in while the enigine is idling (follow the directions).
If you cannot find sea foam, then use regular carb cleaner, unplug one of the vacuum lines running into the intake manifold and spray into the manifold. You can use the whole can (follow the directions).
Both methods will help clean your cat. I've done this before and my emissions are NEARLY ZERO (as good as new!).
Your cat is probably not spoiled, it just aquires a lot of carbon deposits over time making it less efficient.
http://autos.yahoo.com/repair/htmlfiles/qaemmiss.html
http://www.aircarecolorado.com/repair/fixit.htm
12-04-2003, 07:57 AM
#15
The main issue you're not touching is carbon buildups in the system...
If the EGR valve moves (opens and closes) when you stab the gas pedal, then it's probably not the problem.
If your cat is in good shape, then it's probably not the problem.
If you're running lean (which is still speculation at this point), then the O2 sensor probably isn't the problem.
Is your timing set properly? If not, then it should be set to stock.
The indications point to carbon buildup in the engine causing high combustion temps, as everything else is supposedly good.
Try cleaning the engine with some Seafoam or other cleaning method (sucking a bottle of ATF works well too, but probably not as good for the environment), and see what happens then.
If the EGR valve moves (opens and closes) when you stab the gas pedal, then it's probably not the problem.
If your cat is in good shape, then it's probably not the problem.
If you're running lean (which is still speculation at this point), then the O2 sensor probably isn't the problem.
Is your timing set properly? If not, then it should be set to stock.
The indications point to carbon buildup in the engine causing high combustion temps, as everything else is supposedly good.
Try cleaning the engine with some Seafoam or other cleaning method (sucking a bottle of ATF works well too, but probably not as good for the environment), and see what happens then.
12-04-2003, 09:34 AM
#17
Originally Posted by Jeff92se
When using SeaFoam or whatever, be carefull not to use a big vacuum line. Use a SMALL vacuum source like the little line on top of the TB.
I pulled the plugs, and they are so new (less than 7k old) that it is really hard to analyze them. They look, well, brand new to be perfectly honest. They are NGK Iridium IX's, in the 5 heat range which is the stock range. I called my mechanic, and he told me to pull the EGR diaphram all the way up when idling -- the car should stall. If it doesn't, then the EGR valve or something that controls it or the tube that carries the exhaust to the intake manifold is clogged. I am going to NAPA today to pick up some Seafoam, and I think I'm going to replace the coolant temp sensor, thermostat and do a coolant flush. This is just for peace of mind (at to help combat the heat soak my car has). If anyone can host pics, I have pics of my emissions graphs as well as pics of my plugs. More updates as my "progress" continues.
12-04-2003, 09:46 AM
#19
Senior Member
Join Date: Oct 2003
Posts: 523
maybe the gas ur using. if your running a high octane gas that is bought from some stop and rob, itll make it run at a higher temp. my buddy had the same problem. he changed to shell 83 octane from stop and rob 89. that may help too, just run the car for a few miles before the test and give the ecu time to adjust.
12-04-2003, 09:50 AM
#20
Higher octane actually burns slower
Originally Posted by harrymay
maybe the gas ur using. if your running a high octane gas that is bought from some stop and rob, itll make it run at a higher temp. my buddy had the same problem. he changed to shell 83 octane from stop and rob 89. that may help too, just run the car for a few miles before the test and give the ecu time to adjust.
12-05-2003, 04:51 PM
#23
Hey Mike...sad to hear of your car...did u find the parallel link you were looking for?
Yes your thermo class was right...NO2 is produced at high engine/combustion temperatures. The purpose of the EGR valve is to recirculate the exhaust gases into the air intake which in turn decreases combustion temperatures decreasing NO2 levels... so most likely your internal engine/combustion temp is higher than normal.
Your cat mostly deals with hydrocarbons, converting harmful CO to CO2 . It doesnt do much for NO2 since its not a hydrocarbon. High CO2 levels in your results are fine (which actually means your cat is working, as long as u dont have high CO levels).
Did the ECU throw up any codes? Changing engine temp sensor might help if its not been changed. Colonial Nissan up in Medford has em for 9 bucks, how old is your air filter?. U might also wanna have your antifreeze content checked...if the percentage of antifreeze in your coolant is more than 50%, then that will cause the engine to run at higher temps too, especially if its at or more than 70%. ... .
like the Nox link says, might even be your fuel filter or dirty injectors or dirty valves.
good luck with it
Yes your thermo class was right
...NO2 is produced at high engine/combustion temperatures. The purpose of the EGR valve is to recirculate the exhaust gases into the air intake which in turn decreases combustion temperatures decreasing NO2 levels... so most likely your internal engine/combustion temp is higher than normal. Your cat mostly deals with hydrocarbons, converting harmful CO to CO2 . It doesnt do much for NO2 since its not a hydrocarbon. High CO2 levels in your results are fine (which actually means your cat is working, as long as u dont have high CO levels).
Did the ECU throw up any codes? Changing engine temp sensor might help if its not been changed. Colonial Nissan up in Medford has em for 9 bucks, how old is your air filter?. U might also wanna have your antifreeze content checked...if the percentage of antifreeze in your coolant is more than 50%, then that will cause the engine to run at higher temps too, especially if its at or more than 70%. ... .
like the Nox link says, might even be your fuel filter or dirty injectors or dirty valves.
good luck with it
12-05-2003, 06:41 PM
#24
Originally Posted by drstillpatient
Hey Mike...sad to hear of your car...did u find the parallel link you were looking for?
Yes your thermo class was right...NO2 is produced at high engine/combustion temperatures. The purpose of the EGR valve is to recirculate the exhaust gases into the air intake which in turn decreases combustion temperatures decreasing NO2 levels... so most likely your internal engine/combustion temp is higher than normal.
Your cat mostly deals with hydrocarbons, converting harmful CO to CO2 . It doesnt do much for NO2 since its not a hydrocarbon. High CO2 levels in your results are fine (which actually means your cat is working, as long as u dont have high CO levels).
Did the ECU throw up any codes? Changing engine temp sensor might help if its not been changed. Colonial Nissan up in Medford has em for 9 bucks, how old is your air filter?. U might also wanna have your antifreeze content checked...if the percentage of antifreeze in your coolant is more than 50%, then that will cause the engine to run at higher temps too, especially if its at or more than 70%. ... .
like the Nox link says, might even be your fuel filter or dirty injectors or dirty valves.
good luck with it
Yes your thermo class was right
...NO2 is produced at high engine/combustion temperatures. The purpose of the EGR valve is to recirculate the exhaust gases into the air intake which in turn decreases combustion temperatures decreasing NO2 levels... so most likely your internal engine/combustion temp is higher than normal. Your cat mostly deals with hydrocarbons, converting harmful CO to CO2 . It doesnt do much for NO2 since its not a hydrocarbon. High CO2 levels in your results are fine (which actually means your cat is working, as long as u dont have high CO levels).
Did the ECU throw up any codes? Changing engine temp sensor might help if its not been changed. Colonial Nissan up in Medford has em for 9 bucks, how old is your air filter?. U might also wanna have your antifreeze content checked...if the percentage of antifreeze in your coolant is more than 50%, then that will cause the engine to run at higher temps too, especially if its at or more than 70%. ... .
like the Nox link says, might even be your fuel filter or dirty injectors or dirty valves.
good luck with it
12-05-2003, 09:54 PM
#25
Honestly, I would try to get it retested after driving a little while after the seafoam treatment.. see where that gets you before you start spending $$$$ on new parts ($9 ain't much, but still)..
There's a LOT of people having problems passing inspection due to high NOx, and I think it would be beneficial to everyone here to see how your car does after the seafoam treatment.
There's a LOT of people having problems passing inspection due to high NOx, and I think it would be beneficial to everyone here to see how your car does after the seafoam treatment.
12-31-2003, 01:13 PM
#26
Finally passed!!!! (long explanantion)
UPDATE:
So I had to pass inspection by 1/3/04, otherwise my registration would void and I'd be in big trouble. So I went against instinct and bought a cat from NAPA (sorry internetautomar, the NAPA one was cheaper after you factor in shipping and it was already in stock). I had it installed as the front bolts weren't coming off without the aid of a torch. I had also treated my engine with Seafoam. My car still failed! The NOx were about 2x too high, and the HC and CO were almost non-existant. This showed that the hi-flow cat is not as good as a regular one, and that my EGR system was still somehow busted. So I went to my mechanic (who by the way is the coolest and nicest guy in the world, as he dropped everything to help me even though he was completely backlogged due to the holidays). What we FINALLY figured out was this:
- My EGR valve was fine
- My EGRC solenoid valve appeared to be fine
- The vacuum source leading into the EGRC was NOT fine.
What was happening was that the vacuum would pull the EGR valve open briefly under load, but then die out and close it 1 second later. Under sustained loads, the valve would not remain open. My fatal mistake was assuming that this was normal because the car was being revved in neutral, so the load on the engine was not high enough for the computer to tell the solenoid to kick in. We had originally diagnosed the problem as a faulty EGRC solenoid valve (which is an EXTREMELY hard to find dealer part, only 1 dealer in the state had 1 in stock). But I removed it and tested it as per the FSM, and it seemed to pass air through it properly (though I have a feeling the test procedure in the FSM is wrong, based on the explanation of what the solenoid is supposed to do). We then checked the vacuum source to the solenoid, and presto! -- it was not pulling at all, at idle or under load. So, we just routed the vacuum source going to the power valve solenoid directly into the EGR valve, I drove immediately to the inspection station and passed with a 1.75ppm / 2.50ppm max! So, in actuality the problem hasn't been fixed, but I don't give a **** because I dropped $120 on inspection fees and $105 more on a catalytic converter that I didn't need. So I guess the moral of the story is to check your vacuum lines, even if other ones appear to be working perfectly.
So I had to pass inspection by 1/3/04, otherwise my registration would void and I'd be in big trouble. So I went against instinct and bought a cat from NAPA (sorry internetautomar, the NAPA one was cheaper after you factor in shipping and it was already in stock). I had it installed as the front bolts weren't coming off without the aid of a torch. I had also treated my engine with Seafoam. My car still failed! The NOx were about 2x too high, and the HC and CO were almost non-existant. This showed that the hi-flow cat is not as good as a regular one, and that my EGR system was still somehow busted. So I went to my mechanic (who by the way is the coolest and nicest guy in the world, as he dropped everything to help me even though he was completely backlogged due to the holidays). What we FINALLY figured out was this:
- My EGR valve was fine
- My EGRC solenoid valve appeared to be fine
- The vacuum source leading into the EGRC was NOT fine.
What was happening was that the vacuum would pull the EGR valve open briefly under load, but then die out and close it 1 second later. Under sustained loads, the valve would not remain open. My fatal mistake was assuming that this was normal because the car was being revved in neutral, so the load on the engine was not high enough for the computer to tell the solenoid to kick in. We had originally diagnosed the problem as a faulty EGRC solenoid valve (which is an EXTREMELY hard to find dealer part, only 1 dealer in the state had 1 in stock). But I removed it and tested it as per the FSM, and it seemed to pass air through it properly (though I have a feeling the test procedure in the FSM is wrong, based on the explanation of what the solenoid is supposed to do). We then checked the vacuum source to the solenoid, and presto! -- it was not pulling at all, at idle or under load. So, we just routed the vacuum source going to the power valve solenoid directly into the EGR valve, I drove immediately to the inspection station and passed with a 1.75ppm / 2.50ppm max! So, in actuality the problem hasn't been fixed, but I don't give a **** because I dropped $120 on inspection fees and $105 more on a catalytic converter that I didn't need. So I guess the moral of the story is to check your vacuum lines, even if other ones appear to be working perfectly.
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