Failed (CA) smog test, ideas?

[gladis]

Hey all, Im' researching online while typing this thread, but hope that I can get some more direct answers.

My Camry (96 2.2) failed its smog test, for NOx, only on low speed (15mph)

Here are the results:

15 mph:
%CO2 - 14.8
%O2 - 0.5
HC - 11 (54)
CO - 0.00 (0.50)
NO - 1636 (430) - FAIL

25 mph:
%CO2 - 15.2
%O2 - 0.0
HC - 4 (37)
CO - 0.01 (0.47)
NO - 284 (717)

Parenthesis are maximum values. So basically I only failed the NOx test on low speed, anything I should check first? I'd like to fix it myself if I could, but I think my dad is gonna send it to the shop, to not risk failing (and thus another $30)

If nothing else, at least I can have an idea of what might need to be fixed so my mech won't be replacing unneeded parts.

So far online I've read that the engine is either too hot or too lean...

Thanks for all the help!

edit: btw, the car has no CEL

[gladis]

k did some reading and apparently a dirty/defective EGR valve/solenoid is usually the culprit?

Would this be consistent with my results (ie, pass everything, except for high NO)

btw, avg values for NO are 57 and 50, so even my passing one is 5.5 times the average, though still way below the limit.

If it is, how do I remove the EGR valve and check to see if its dirty? I know where the valve is, but not sure how to remove/check it.

[fenixus]

check this out, unbolting EGR valve along with it's bottom pipe is not that hard:
DIY : EGR Valve removal

you can clean it up well with seafoam, replace gaskets and it should be fine.

I'm not sure if that's what actually causes high NO levels at low speeds.

[JohnGD]

The EGR flow seems to be working fine at higher speeds. Borrow a MityVac from Autozone's free loaner tool program. Pull vacuum on the EGR valve and see if it makes your engine run rough and/or stall. If so that valve checks out.

You might want to pull a good vacuum and make sure the valve opens fully. Like that "bang" it several times to help shake off loose carbon that you can. This is used by modern digital EGRs.

Then connect the MityVac to the throttle body ports P and R. And read off the vacuum as you increase the throttle from idle to 2500 rpms. They should read 0 to full engine vacuum as the throttle plate opens past them.

Dirty or plugged throttle body ports won't give the system the proper vacuum signals. I wonder if Port P is giving you some problems at low speeds, among other possible causes.

Originally Posted by gladis

Hey all, Im' researching online while typing this thread, but hope that I can get some more direct answers.

My Camry (96 2.2) failed its smog test, for NOx, only on low speed (15mph)

Here are the results:

15 mph:
%CO2 - 14.8
%O2 - 0.5
HC - 11 (54)
CO - 0.00 (0.50)
NO - 1636 (430) - FAIL

25 mph:
%CO2 - 15.2
%O2 - 0.0
HC - 4 (37)
CO - 0.01 (0.47)
NO - 284 (717)

Parenthesis are maximum values. So basically I only failed the NOx test on low speed, anything I should check first? I'd like to fix it myself if I could, but I think my dad is gonna send it to the shop, to not risk failing (and thus another $30)

If nothing else, at least I can have an idea of what might need to be fixed so my mech won't be replacing unneeded parts.

So far online I've read that the engine is either too hot or too lean...

Thanks for all the help!

edit: btw, the car has no CEL