I failed emissions again today. I cleared out a clog in the EGR system and was hoping that would fix it, but I guess not. It did help though, I passed the 15 mph test, but failed the 25. I decided to check my ecu for codes and its 3 long 3 short, which according to ser.net thats my o2 sensor. This really sucks *** I just changed my o2 sensor maybe 6 months ago and my gas mileage is fine. Could a bad o2 sensor make me fail emissions? Could something else other then a bad o2 sensor cause an o2 sensor ecu code? Thanks.

and oh yeah, Iv got a 91', does it have only one o2 sensor or does it have one in the cat too? If its only got one, what is that ground wire on the cat for?

Which part of the high-speed test did your car fail? HC, CO or NOx?
Knowing the above, you can find plenty of information in the SE-R.NET archive (http://www.se-r-list.org/archives/).
You have one O2 sensor and you answered your own question about the strap.

I failed both NOX and HC

ok, I just did a little bit more testing. I think my egr is still not working. I tested the vacuum pressure between the BPT valve and the EGR valve. I got a vacuum when I first step on the gas, but after that the vacuum subsides. It will not maintane a vacuum. When I blip the throttle the vacuum pressure spikes, then it drops down to zero. Testing the pressure just before the bpt valve resulted in the same results (so the bpt valve is ok i assume). Please help me. I couldnt see where that hose went too, it went down to far. I need to pass emissions, I leave for school in 9 days!!! I did search the archives, basicly high nox is from a malfunctioning egr valve and a bad cat, but mainly the egr valve. The question is though is why is my egr valve not working? And also if the o2 sensor is not working right could I be running rich therefor causing a problem with the cat? ug, this sucks. oh, my hc where also high, so could a bad egr valve contribute to this or is that most likely my cat?

I failed the samethings in my se-r too :(.

Originally posted by mpg9999
I failed both NOX and HC

You never mentioned after testing the BPT whether the EGR opened under vacuum. The valve on the bottom of the EGR should pop inward as vacuum is applied to it. Also, you mentioned the ground-strap on the cat. It is indeed for grounding the O2 sensor. AFAIK, the O2 sensor and the cat are more related to the high HC count, whereas the Cat and EGR are related to the high NOX. I believe there is a self-test for the O2 sensor descibed in the FSM(and on SE-R.net I think). Also verify that the EGR is opening under vacuum. If both of these are functioning properly, I would consider replacing the cat(a universal CATCO unit is about $60 from Summit). Also, where is your timing set? I read in the archives that retarding the timing can help with NOX, but I think it may raise HC. Worst-case scenario, I would think about taking to a shop and have them try to diagnose it. Especially if the shop has emissions testing equipment, then they can test-n-tune. Good luck, and keep us posted.

Ben
92 SE-R

Move to Florida. No Testing.

Actually a trick to pass is to pour 1 bottle of Rubbing Alcohol (I'm serious) in your tank about a couple miles before the testing station. The alcohol burns much cleaner than gas alone. I did this with an old van once that kept failing.

Well im not sure if the egr valve is working since its not getting any vacuum pressure. I need to find out why im not getting any pressure. Well actually the shop does since I took it in this morning, if I had more time id do this myself but I leave for school soon and my car needs to be registered. Oh yeah, my timings at 15.

So you're having the shop fix it? If so, I'd like to know what they come up with to fix it. Plus, it'd be great to have in the archives.

Ben
92 SE-R

EGR is not supposed to operate at idle or full throttle.

If you failed both HC and NOx, I'd look first at the cat. It's the most expensive part to replace and there's no test, unfortunately.

I'd look first at the cat. It's the most expensive part to replace and there's no test, unfortunately. [/QUOTE]

I guess that's in the eyes of the beholder. However, you can pick up a Dynomax or Catco cat for under $100. www.jegs.com. I have a Dynomax and it works fine.

Good luck!
Curt B. Shumaker

Yeah, I was wondering if I had a cat problem too just because of the high HC. But I do know for sure that the egr system is not working, but the egr valve and the bpt valve on there own work fine, the bpt valve is just not recieving the vacuum it should. I did have the cat off of the car a few months ago and visually it looked fine. Once the egr system gets fixed ill run my ecu for codes again and see if I still get a code for the o2 sensor, if so, ill replace it then take my car to get it tested again. If it fails again then ill replace the cat, then it better pass. Ill be sure to post my results. The car should be ready tommorow.

I got my car back today, they said they did an "emissions tuneup" and they found a vacuum leak. They did an emissions test and I passed 861 NOX limit is 1072. HC limit is 147 and I got 146. The HC makes me think my cat could be bad. When I got the car home I tested to see if the EGR valve was working and nope, still doesnt work. Vacuum is doing the same thing it was befor. What a bunch of crap, they where supposed to have fixed the egr valve. They even called and told me it wasnt working (when I already told them that when I droped it off). I bringing it back tommorow. I also checked my ecu for codes again and it says my o2 sensor isnt working. I wonder why my ecu isnt giving me a code for a malfunctioning egr valve?

Unless you're OBDII(and I think you said you had a Classic), most OBDI ECUs don't check EGR status. OBDI Cali equipped cars had to have an EGR temp sensor that verified the EGR status, but without that the ECU has no idea if its working or not.

Hey, at least it passed this time. Now you don't have to worry about it for another year. ;)

Ben
92 SE-R

My friend with a 96 GXE just failed CO and nox emmissions here in jersey. I diagnosed it as a bad front o2 sensor. His CO was 3 times the standard and his nox was fairly high as well.

Spent 20 bucks on a new Bosch o2 sensor (don't ask how i got it so cheap..i'm still trying to figure that one out) and now his readings were crazy low, just like they should be on a 60,000 mile car.

iknow this is an old post but have you tried checking the o2 ground on the cat?

yeah. It passed so im not to worried about it right now. In the future im going to have a close look at the cat . Its kinda strang though, im still getting a bad o2 code, and get 35 mpg highway.

-Mike

NismoSER,

Just had my inspection done. I just paid though instead of going thru the hassle. Besides it's for 2 years.

I know for a fact I'm not going to pass, but I'm not even talking about emissions. New JerZ is so uptight about anything aftermarket it becomes a huge PITA. I went with my buddy to get his Jetta inspected. He passed all emissions, but failed the test because he had hyper green headlights (which actually look yellow) and because his exhaust was NOT stock! And not because of the sound, it is actually pretty quiet, but simply because its anything other then stock. What a load of crap. They guy told us to put on the stock exhaust and come back, we just laughed at him. We ended up having a "friend" do the inspection.:D A couple extra $ and no problems.