I have a 98 contour se w/2.0 engine. Failed calif emission test, high nox. Cooling system, fuel control are working well. LTF is +6% at cruise, well within parameters. Oxygen sensor varies from .1 to .9 volts, with it going from .1 to .9 in less than .1 seconds, which is a good response rate. No egr system on this car. Throttle plates are very dirty, we will clean them but do not feel that will affect nox under load. Has anyone had this problem? It is probably a catalytic converter problem, car has only 48k on it though. Any thoughts??
-
Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.
You can register to join the community.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
High nox
- Thread starter Dupie24
- Start date
I have a 98 contour se w/2.0 engine. Failed calif emission test, high nox. Cooling system, fuel control are working well. LTF is +6% at cruise, well within parameters. Oxygen sensor varies from .1 to .9 volts, with it going from .1 to .9 in less than .1 seconds, which is a good response rate. No egr system on this car. Throttle plates are very dirty, we will clean them but do not feel that will affect nox under load. Has anyone had this problem? It is probably a catalytic converter problem, car has only 48k on it though. Any thoughts??
How do you get away without a EGR system? If it is a catalytic converter problem, you should fail due to a P0420 code (unless you have a mileliminator installed on the lower O2 sensor). Clean the throttle plates. That could affect the proper running of the engine..... No egr system on this car. Throttle plates are very dirty, we will clean them but do not feel that will affect nox under load. .... It is probably a catalytic converter problem, ..
contourspd98
Veteran CEG'er
NOx is produced in an engine by either too much heat or pressure. Or both. Could be a # of things. With you LTFT +6 then the computer is adding fuel for a lean condition. Maybe you have a small vacuum leak somewhere, or a clogged injector. But with the O2 switching that tell me that it probably wont be an injector.
One could be no EGR system.NOx is produced in an engine by either too much heat or pressure. Or both. Could be a # of things. ...
Big Jim
Hard-core CEG'er
That engine does not have an EGR valve. It has variable valve timing on the exhaust valves, which accomplishes nearly the same thing. If the VVT system isn't functioning it can lead to high NOX.
What are the other gas readings from the smog test. That may tell us something.
The cat monitors will not tell you if the reducing catalyst part of the cat is misbehaving, only the oxidizing part.
Cats these days are made to reduce HC and CO emissions by encouraging more oxygen to those molecules (oxidizing), and to reduce NOX by removing oxygen from NOX molecules (reducing). The P0420 code only speaks to the oxidizing function of the cat.
NOX is not generated until the engine is under load (and thus the need to do the test on a dyno). NOX is only generated when the combustion temperatures are hotter than intended. Things that can contribute to that are EGR not functioning (not applicable to your engine), exhaust VVT not functioning (could apply to you), too much ignition timing, air fuel mix too lean. And, it is also possible that the cat wasn't hot enough. It helps to drive the car in a spirited manner for about 15 or 20 minutes prior to the test, but don't let it cool off by waiting in line for another 15 to 20 minutes.
What are the other gas readings from the smog test. That may tell us something.
The cat monitors will not tell you if the reducing catalyst part of the cat is misbehaving, only the oxidizing part.
Cats these days are made to reduce HC and CO emissions by encouraging more oxygen to those molecules (oxidizing), and to reduce NOX by removing oxygen from NOX molecules (reducing). The P0420 code only speaks to the oxidizing function of the cat.
NOX is not generated until the engine is under load (and thus the need to do the test on a dyno). NOX is only generated when the combustion temperatures are hotter than intended. Things that can contribute to that are EGR not functioning (not applicable to your engine), exhaust VVT not functioning (could apply to you), too much ignition timing, air fuel mix too lean. And, it is also possible that the cat wasn't hot enough. It helps to drive the car in a spirited manner for about 15 or 20 minutes prior to the test, but don't let it cool off by waiting in line for another 15 to 20 minutes.
contourspd98
Veteran CEG'er
One could be no EGR system.
Yeah, but zetecs don't have EGR systems. At least I thought that they didn't.
99SEinLivonia
New CEG'er
What he said.
What he said.
EGR is specifically used by OEMs to reduce NOX because it dilutes the fuel-air mixture with burned air (no/less O2 present - hence no extra fuel required). The emmision-benefit to this is that it lowers combustion temps, thereby reducing NOX generation. While I don't know the working part of your EGR system (with VVT it uses internal EGR->no EGR valve) BigJim is correct in saying that either it was tested with a cold cat or something similar. It may be that you have a bad or poisoned catalyst brick.
What he said.
That engine does not have an EGR valve. It has variable valve timing on the exhaust valves, which accomplishes nearly the same thing. If the VVT system isn't functioning it can lead to high NOX.
What are the other gas readings from the smog test. That may tell us something.
The cat monitors will not tell you if the reducing catalyst part of the cat is misbehaving, only the oxidizing part.
Cats these days are made to reduce HC and CO emissions by encouraging more oxygen to those molecules (oxidizing), and to reduce NOX by removing oxygen from NOX molecules (reducing). The P0420 code only speaks to the oxidizing function of the cat.
NOX is not generated until the engine is under load (and thus the need to do the test on a dyno). NOX is only generated when the combustion temperatures are hotter than intended. Things that can contribute to that are EGR not functioning (not applicable to your engine), exhaust VVT not functioning (could apply to you), too much ignition timing, air fuel mix too lean. And, it is also possible that the cat wasn't hot enough. It helps to drive the car in a spirited manner for about 15 or 20 minutes prior to the test, but don't let it cool off by waiting in line for another 15 to 20 minutes.
EGR is specifically used by OEMs to reduce NOX because it dilutes the fuel-air mixture with burned air (no/less O2 present - hence no extra fuel required). The emmision-benefit to this is that it lowers combustion temps, thereby reducing NOX generation. While I don't know the working part of your EGR system (with VVT it uses internal EGR->no EGR valve) BigJim is correct in saying that either it was tested with a cold cat or something similar. It may be that you have a bad or poisoned catalyst brick.
Last edited:
Yeah, but zetecs don't have EGR systems. At least I thought that they didn't.
pre98 zetecs have an egr system.
the post 98 zetec have VCT which adjusts the exhaust cam timing to do the same basic thing.
Thanks so much for all the replies. I will check into the variable valve timing system if throttle plate cleaning and spirited drive before test doesn't work. Info on the cat monitor is great, did not realize cat monitor is only checking the hc/co bed of the cat, thanks for the info. Hopefully I can get this customers car smogged, information here is great!!! Thanks again
Bob
Bob