emissions help - 92 celica gt

[obpTR]

First of all, thanks in advance for any help.
I'm in a difficult situation trying to diagnose my sister's 92 celica gt (120k miles) that failed CA emissions. The car's thousands of miles away and she cant easily send me pics/sound clips etc so I'm trying to troubleshoot over the phone without any way of hearing or seeing the car .

So here's the deal:
1) failed NOx (over twice the upper limit at low and high rpm)
2) hc, COx, etc are all fine
3) she says exhaust note sounds the same and car idles the same.
4) recently had timing belt changed at dealership
5) had a spark plug blow out (literally shot out) not too ong ago

Based on this I'm thinking the high NOx is due to running lean, timing, or cooling system. I had her have the dealer check the cooling system when the spark plug blew, so assuming they're right in saying its ok and I'm also assuming they adjusted the timing right.

So I'm thinking she's running lean and should:
1) change the fuel filter
2) run some fuel system cleaner
3) clean out the pcv valve
4) run a few gallons of higher octane gas

So my questions are:
1) what else am I overlooking? what else should she do?
2) can someone provide a clear picture of the pcv valve that I can send her? (I told her what it should look like and she is able to locate the valve cover, but she's not totally comfortable working on cars and needs the reassurance)
3) am I correct to assume that given the COx and HC readings and the fact that there is no audible rattle from the exhaust that the cats are most likely ok?

She passed emmissions easily last time and she hasnt noticed any performance differences. No new sounds, car still gets incredible gas mileage, etc. The car was warm when smog checked (10 mile highway drive with some city driving) so the cats were warm but the car wasnt too warm.

CN: Need help passing emissions on a 1992 celica gt that only failed NOx. Need clear picture of pcv valve. Need further advice.

[toyomoho]

I would assume the dealer timed the car OK, but. I have heard about sparkplugs popping out. Was this a defective plug, or just not installed properly?

Some things that seem to come up often with excess NOX are; converter problem, EGR, O2 sensor.

Before you do anything check the link below for info on NOX problems. Each type of gas seems to have its own problem sources.

http://www.troublecodes.net/articles/smog.shtml

[OEMonkey]

Most likely a problem w/ the EGR system. Either the valve itself, vsv, transducer, vac lines, clogged passages, or all of the above.

[obpTR]

Thanks for the quick replies.

Last time I saw her (6 months ago or so) I ran seafoam through her car and removed and cleaned the throttle body. IIRC I ran the seafoam through the brake booster cable,valve cover, and a vacuum hose off the throttle body.

Would this have likely cleaned the egr valve or does her engine have removable egr ports (my old f-series honda motor did) or something similar?

toyomoho - Its possible that the plug was not installed properly, but the plug did not seem defective (threads ok, normal wear, etc...). The tech that looked at her car said something to the effect of "it happens."

[toyomoho]

I have never seen or heard about a complete plug popping out of an engine because of normal wear and tear. They are screwed in too well. This unless the threads on the cylinder head were stripped or close to it, there was something wrong with the plug or the plug was not screwed in very well.

It is also possible just the ceramic insulator portion of the plug popped out, leaving the spark plug steel shell in the head. The plug was defective.

I would assume a mechanic with service info could check out the EGR and 02 system reasonably quickly.