I've searched over an over and can't seem to come up with a definitive answer.

I have a 92 Civic Cx w/ 94 usdm GSR b18c1 engine. I've passed at NJ MVC facilities in the past with my current set up. The car has a carsound high flow converter. This time, I failed NOx, but passed HC and CO%. Numbers were as follows:

NOx standard: 1372 // my car: 2379!
HC standard: 173 // my car: 147
CO standard: .97 // my car: .64

Also, something I noticed when looking at my older inspection reports is that it appears that my HC and CO% numbers have increased each time I've had the car inspected.

Magnaflow/CarSound's website suggested these possible causes: EGR, lean AFR, leaks, run-in converter, use larger converter.

I found this suggestion in an archived article:

This is a suggested order for NOx failure of things to check:
1. EGR System
2. O2 Sensor
3. Timing/Spark Advance
4. Catalytic Converter
5. Incorrect/faulty thermostat
6. Coolant Temp Sensor may be open
7. MAP Sensor
8. MAF Sensor
9. Other sensors/switchs (uhhh yeah, ok)
10. Fuel Injection System
11. Faulty On-Board COmputer
12. Computer PROM
13. Internal Engine Repair

After posting a similar topic in the "hybrid" section I feel like I'm closer to the answer, but still not confident about what I've been told. My goal is to correct the problem without replacing any parts that do not need replacement.

1) There does not appear to be an exhaust leak.
2) I have to look at timing - I'm running lean so I may have to retard the timing.
3) I'm skeptical about the problem being related to the o2 sensor or the catalytic converter as I've read that they have little control over NOx - my car passed for HC & CO, which seem to be converter related issues.
- Does the converter and/or o2 sensor have a bearing on NOx?
4) My car's heat does not work so maybe thermostat could be an issue?


Please offer your best suggestions, thanks!

 

my suggestions:

1. EGR System
2. O2 Sensor
3. Timing/Spark Advance
4. Catalytic Converter
5. Incorrect/faulty thermostat
6. Coolant Temp Sensor may be open
7. MAP Sensor
8. MAF Sensor
9. Other sensors/switchs (uhhh yeah, ok)
10. Fuel Injection System
11. Faulty On-Board COmputer
12. Computer PROM
13. Internal Engine Repair

 

So you just cut and pasted what was written? Thanks...

1) My car does not have EGR system!
2) Nowhere, other than this list have I found ANYTHING about the o2 sensor affecting the NOx - if it does please explain.
3) Timing - as stated in my email I plan to look at this and adjust if necessary...
4) Catalytic converter - this might be a possibility, but like the o2 not much info on this site points to the converter since the CO and HC were okay.
5)Thermostat - this was another question I raised.
..... The rest don't seem too logical.....

Any OTHER suggestions..

 

start with your timing

 

Maybe this will help a little.

NOx destruction in the cat requires the presence of a bunch of excess oxygen. That's why high NOx can sometimes be due to a lean a/f ratio. And THAT is how your O2 sensor plays a role in the NOx levels, since the ECU adjusts a/f ratio based in part on O2 sensor readings.

Regarding timing, in CA they actually put a gun on there and measure it directly. If out of spec, they flunk you right then, and abort the rest of the test. So, since they actually completed the test for you, are you saying that NJ does not directly check timing? What I'm getting at is chances are the smog guy already checked your timing and it was ok. Look on your paperwork and see if the timing measurement is written on there - it is in CA.

Good luck and count your blessings you don't have to deal with EGR. Diagnosing and fixing EGR problems is a serious, serious money pit.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rainmaker &raquo;</TD></TR><TR><TD CLASS="quote">Maybe this will help a little.

NOx destruction in the cat requires the presence of a bunch of excess oxygen. That's why high NOx can sometimes be due to a lean a/f ratio. And THAT is how your O2 sensor plays a role in the NOx levels, since the ECU adjusts a/f ratio based in part on O2 sensor readings.

Regarding timing, in CA they actually put a gun on there and measure it directly. If out of spec, they flunk you right then, and abort the rest of the test. So, since they actually completed the test for you, are you saying that NJ does not directly check timing? What I'm getting at is chances are the smog guy already checked your timing and it was ok. Look on your paperwork and see if the timing measurement is written on there - it is in CA.

Good luck and count your blessings you don't have to deal with EGR. Diagnosing and fixing EGR problems is a serious, serious money pit.</TD></TR></TABLE>

RAINMAKER, i give you props for having the patience to answer this guy. Seems he doesn't know what the search feature is.

in any case, here in milwaukee our emissions do not directly check timing. from what i've seen/read, cali is the absolute most restrictive when it comes to emission regulation.

as far as egr system analysis goes, it's really not that bad. most vehicles, barring obd2 fords, have only the egr valve. when that valve fills with carbon, it's time to replace it. some people believe you can take it apart and clean it, but you can't. couple this with some manufacturers getting away from being purely vaccuum based, but electronis, and yes it can get expensive. fords dont only have an egr valve, they also have an egr pressure sensor and an egr position sensor. but thats neither here nor there. when messing with a vehicle that is obd1 and older, and having an egr issue, all it involves is replacement and cleaning the port the valve mounts to. nothing too dramatic in terms of diagnosis.

again, props for having the patience to answer this guy. i would have as well, but it seems he doesn't handle my sarcasm well.

 

Do a complete tune up, oil change, and like said, try to advance your timing, but doing so may increase your HC. If you can find some, run some methanol with you gas, or use some "Heat" fuel antifreeze/water remover, it got some methanol in there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rainmaker &raquo;</TD></TR><TR><TD CLASS="quote">Maybe this will help a little.

NOx destruction in the cat requires the presence of a bunch of excess oxygen. That's why high NOx can sometimes be due to a lean a/f ratio. And THAT is how your O2 sensor plays a role in the NOx levels, since the ECU adjusts a/f ratio based in part on O2 sensor readings.

Regarding timing, in CA they actually put a gun on there and measure it directly. </TD></TR></TABLE>

Thank you that does help. I do not believe they measure timing in NJ. But I have passed before with correct timing, so my goal is to do the same. I may adjust my timing but will keep it within the specified range.

- so realistically the issue could be the o2 sensor or cat, correct? is that more likely than just changing the timing?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GRAF-FITI &raquo;</TD></TR><TR><TD CLASS="quote">

RAINMAKER, i give you props for having the patience to answer this guy. Seems he doesn't know what the search feature is.

again, props for having the patience to answer this guy. i would have as well, but it seems he doesn't handle my sarcasm well. </TD></TR></TABLE>

GRAF-FITI please do a bit of your own research and look up the definition of sarcasm. I don't think you have a handle on that word yet. The bulk of what I wrote in my post was derived from the search feature.

Why don't you try using the search feature and prove me wrong - find something solid that answers my questions. If you can, please post it... If you can't don't try to contribute. We've already established that there is no egr on my car so your rant about "egr analysis" was completely unnessary rhetoric.


Thanks again Rainmaker and others who have offered suggestions. I will start with the timing and if that's not enough will look at replacing the o2 or cat.

Any suggestions on which is more likely if it is not fixed with timing adjustments?

 

Im going through the same situation with my hatch right now. except i have a high NOx and a high HC. i have a jdm itr in my 98 civic. i live in milwaukee and atempted to pass emissions once. my result was 4 times the NOx amount and 3 times the HC amount. 2 things that i can already tell you that are wrong with mine is that my o2 sensor is pretty bad, and I do not have a cat on my car. i have an egr and evap and pcv hooked up but i dont know how well they are actually doing for me since i bout the car wiht the motor in it and it seemed that the evap off the top of the manifold was internally plugged. Im replacing the o2 sensor and puting an apexi n1 cat back on today and trying my luck again. my time is a bit advanced and if i fail again ill retard that. but anyways good luck with the cali smog testing cuz i know its pretty intense over there.

 

jlsmi2 - I wouldn't toss your cat just yet. If your cat was bad your HC would be high as well. It may very well be less efficient than when new, but chances are it's still ok.

B18C_Powered_EK - you're funny. You don't have a cat or an O2 sensor - pretty sure your problem is somewhere in there

"toss your cat" - sounds rated PG-13...

 

NO lol its not that i dont have one well i dont have a cat but my o2 sensor is bad. and i only went and tried so i could get the extension

 

I had the same problem. Just retard the timing a bit and make sure your cat is hot as hell when they test it.

this image was taken from the team-integra.net forum

hope this helps




here's the thread on team integra with the same problem

http://www.team-integra.net/fo...earch

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TemjinX2 &raquo;</TD></TR><TR><TD CLASS="quote">I had the same problem. Just retard the timing a bit and make sure your cat is hot as hell when they test it.

this image was taken from the team-integra.net forum

hope this helps




here's the thread on team integra with the same problem

http://www.team-integra.net/fo...earch
</TD></TR></TABLE>

Nice. I read the thread from team-integra.net and found another possible suggestion: "I was reading my tech training manual i have from uti, and it says that the only cause for high NOX is temperature. so meaning its only one of 2 things or worse both lol.

inefficient cooling system or a lean condition..." (Robywolf from team-integra.net)

 

[QUOTE=Rainmaker]jlsmi2 - I wouldn't toss your cat just yet. If your cat was bad your HC would be high as well. It may very well be less efficient than when new, but chances are it's still ok.[QUOTE]

That's what I've been thinking. Looks like its either timing, a leak or faulty cooling system. I hope its that easy. Thanks for all the help. I will check in once I make a change and inspect.