I have a 95 accord ex, i took it in for inspection the first time it failed on high nox.
high speed 1615- low speed 2012
I changed the egr valve and cleaned the IAC valve screen, took it back for reinspection and now it failed for higher nox and now co%.
high speed nox 1692- low speed 2363
1st test co% was high speed .21- low speed .08
2nd test co% was high speed 2.58- low speed 1.60
what did i do that made the nox and co% higher?

 

Clean the ports. In the Common DIY Threads there is a how to.

Tune up items are up to date?

 

found the thread and gonna try that thanks. and we got the car in july and i checked the airfilter, had the oil changed, changed the plugs, and had my wife's work check it out. other than that haven't done anything else. it runs great only problem was idle dropping too low when a/c was turned on but cleaning the IAC filter took care of that.

 

Some would suggest new o-rings for the injectors...

At some point you might wat a new cap and rotor just so you have a good base line of when they were done.

Let us know how it turns out....

 

Nothing. Like poorman said, cleaning the EGR ports should take care of the NOx, but IAC & EGR cleaning/replacement shouldn't result in a ten-fold increase in CO. How old is the oxygen sensor?

 

well poorman i just finished the ports and it looked just as bad as the thread pics from the instructions. completely clogged up. Fixing to check the plugs to see how bad they are. your probably right i should go ahead and do the cap and rotor too. thanks for the help.
and Roader not sure we just got the car in july, but i dont understand why the co passed the first time, thats whats confusing me, dont understand why that changed on what i did.

 

Check that all the vacuum lines were put back on & no vacuum leaks. Aside from that, check the O2 sensor output voltage output. Google honda-tech(dot)com, 1110253. You should find a thread called "fuel too rich." Post #6 helped me when I had the same problem with very high CO (and high HC.)

You might want to check the ECT sensor resistance too.

Mine passed with flying colors after putting in a new O2 sensor.

 

While the O2 could be the/part of the issue...I'd check the plugs, decide on them and the cap and rotor, then I would have it re-tested (here there is a small fee for re-tests (~$9).

If it fails, be sure to to the numbers/print out and post them up. With the port cleaning done and it still fails the new numbers will help find what is left to test (O2, exh leak, timing, ect)

 

the plugs had a little carbon on them but the gaps were still good so cleaned them and put them back. And im gonna have it retested tomorrow because i read somewhere that the clogged ports would make it run lean, so im wondering if putting the new egr valve on and cleaning the IAC is what triggered the high co% by having it all trying to work right. If it fails again then i will go with the o2 sensor. And luckily the place i'm going to doesn't recharge for retesting. and thanks again for all the help.

 

Good to hear. Also nice to know there isn't a charge for the re-test, again if it fails. Get the numbers as it will help in figuring out what else might be the issue....but really think you will be fine ...positive thoughts for you.