Greetings,
My 1994 Accord LX 2.2L 4 cyl has failed emissions test.
The CO is a bit above the limit, both HC and NOX are well under the limits.
I tried to paste in all the results below from the past several tests but it's a little hard to read.

Interestingly, it failed in a similar manner 6 years ago (3 tests ago, we have bi-annual testing here); the CO was high, and also that time the NOX was highish but still in spec. At that time I replaced the oxygen sensor, as well as a new pvc valve (i have no reason to think it need one, but it was only 2.99!), plus a bottle of "guaranteed to pass" (you gotta love that name!). It then passed with flying colors.

The car had 90,000miles when it failed in 2007. In the meantime it has become hardly used -- it is now at 101,000 miles, so less than 2,000 miles a year. It is used maybe once a week on a 10 to 15 mile trip (so not really really short, but still...). We live in Phoenix AZ, it seems like it has no trouble getting up to temperature.

Fuel economy seems to be holding up very well at ~ 26mpg ; however since it's now driven very little, it's hard to say what it is at the moment.

I had never failed emissions before the 2007 episode, and i am the original owner.

So the question is what to do this time? I have a tendency to want to simply do the same thing I did in 2007 an hope for the best! The first re-test is "free"; but after that it's 30 bucks a crack...

I just realized the plugs have 70K on them (and are 14 years old), and they're just plain plugs (not "platinum" or whatever), the manual says to replace them every 30k miles/2 years -- so I will definitely do that, too.

[Edit: oh, should mention: the check engine light isn't on. It wasn't on back in 2007 failure, either]


date / -Test- / HC , limit / -CO , limit- / -NOX , limit-
2001 / IM147 / 0.18 , 0.80 / 3.04 , 12.00 / 0.90 , 2.00
2003 / IM147 / 0.18 , 0.80 / 4.73 , 12.00 / 0.44 , 2.00
2005 / IM147 / 0.10 , 0.80 / 4.99 , 12.00 / 0.15 , 2.00
2007 / IM147 / 0.37 , 0.80 / 13.18 , 12.00 / 1.01 , 2.00
2007 / IM147 / 0.18 , 0.80 / 4.21 , 12.00 / 0.35 , 2.00
2009 / IM147 / 0.22 , 0.80 / 4.56 , 12.00 / 0.50 , 2.00
2011 / IM147 / 0.13 , 0.80 / 5.17 , 12.00 / 0.46 , 2.00
2013 / IM147 / 0.31 , 0.80 / 14.06 , 12.00 / 0.74 , 2.00
2013 / IM147 / 0.11 , 0.80 / 2.54 , 12.00 / 0.49 , 2.00 *RETEST* *PASSED*

 

1st Update: I replaced the spark plugs today and there appears to be oil everywhere in there (where the plugs are).
I don't know exactly what that means -- but I know it's not good! :-(

I can say it doesn't seem to be using oil (though as i mentioned, it only gets driven less than 2,000 miles/yr. And it doesn't, yet anyway, seem to have any visible smoke in the exhaust.

Edit: apparently my spark plug wells are leaking, a common problem, apparently
I wonder if/how that might affect emissions?

 

Most likely oil in plug wells is not related to emissions failure.

See following link for good info on emissions:

BAT Auto Technical-Professional mechanics giving advice-An Educational Site w/ OBD2 Trouble Codes and Technical info & Tool Store.

good luck

 

thanks. So I haven't gone through the retest yet; I put in the plugs and new O2 sensor, and it seems to me the car runs very well.

BUT now i have a bad feeling that that stuff i did isn't going to help, because...

I just discovered that the detailed graphical test results are available, thanks to the wonders of the internet!
Sorry about the non-standard link (numerical ip) but i promise it's not malware, that's the way AZ MVD does it for some reason.

AZ Drive Trace (test results from failing 7/5/2013 test; image of results is inserted, below)

In any event; what the graphs show is everything seems really good for the first 60 seconds of the test, then when the speed hits like 30mph (and heading up to, say 40mph) --- it's not clear to me what gear it's in --- anyway; the CO goes completely haywire, pegging at 150 (the test limit average must be below 12). Ug. It seems to me this must indicate something -- any ideas?

Edit: here's a picture of the graph (in case the link above doesn't work):

 

High CO occurs only in a rich condition (not enough air for amount of fuel). This might be caused by badly restricted air filter, or too much fuel; leaking injector, leaking fuel pressure regulator, or lazy O2 sensor.

High CO seems to occur under acceleration; too much fuel? check fuel pressure regulator by pulling vacuum reference line and sniffing for fuel smell. Any fuel smell would indicate ruptured diaphragm.

good luck

 

Passed. Passed with flying colors. I suppose this is classic "lazy O2 sensor" behavior?

Below is a link to the graphical result (i LOVE the data. I can't believe all this data has been sitting there all these years and I never knew about it!)... though for some reason the graphs end at 30 seconds and ~ only 30mph. I was in the car with the guy and it did go longer/faster than that, so i'm glad it passed but a little miffed i didn't get all my data.
For the curious / interested: We use the IM147 test in Arizona. I'm a little surprised i can't find the test protocol (they also refer to it as the "drive trace" -- the technician drives the car on rollers at very specific speeds and have to cause very specific gear changes)...

AZ Drive Trace My passing test 7/11/2013

Here, is an example of what a passing test normally would look like, it lasts longer and continues to higher speeds (a friend's car):

AZ Drive Trace passing test of a friend's car

Edit: apparently the test-rig computer is programmed such that if the car is doing really well that it's going to pass the test in any event; so it terminates the test early.