Toyota Repair: MR2 in Texas, nox emissions, high speed test

Question
Subject: Emissions
Question -
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Followup To
Question -
i have a 1992 MR2 nonTurbo. It failed on the Nox by 303ppm. Do you think a tune-up will make it pass or will I need to do more. the HC reading were good but the CO only passed by 7%.


Answer -
new plugs and wires for starters. then test again.
could also be a clogged pcv.

I've replaced the plugs & wires, distributor cap & rotor, cleaned & checked the EGR vacuum modulator, EGR valve & VSV valve. I've found that the VSV valve does'nt appear to work properly. When I jumper TE1 to E1 I have low vacuum @2500rpm whether the engine is cold or hot and the water temp sensor checks OK. (500 ohm with engine warm)

It's also hard to have it checked whenever I want. It's $40 a pop and I have to wait in line.
Do you think the VSV valve not working will raise the Nox 300ppm?



paul p. Answers -
absolutly!!!

Paul,
I failed the inspection.
My 1st readings were 63 HC, .7 CO,.2 O2, 1312 Nox @2104 rpm. @1983 rpm they were 59 HC, .7 CO, .2 O2 & 1367 Nox.
Then I fixed the EGR VSV, replaced plugs & wires, rotor & cap, air filter & cleaned the EGR modulator filter. Vacuum readings matched the manual.
On the re-inspection the readings improved to 36 HC, .3 CO, .2 O2 & 1185 Nox @ 2122 rpm (the Nox failed here)

@1902 rpm the readings were 73 HC, .4 CO, .2 O2 & 1087 HC.  

The high speed standards are: 136 HC, .76 CO & 984 Nox.
The low speed standards are: 141 HC, .79 CO, & 1088 Nox.

As you can see things improved overall but the Nox barely passed the low speed test and failed the high speed test.
I'm wondering what to do next. Re-check the air/gas mixture, the emission system, O2 sensor, replace the Cat coverter, ......

I need some expert help & hope you can help with this one.

It also dawned on me that now that Texas has just started this new standard that maybe my Nox emissions were never low enough to meet this new standard. Maybe I need the rear converter like is on the California models?

Help!!!!!!!!!!!!!!!

Answer
from my experiance being from ny as an certified state inspector as well as a tech i know that the vin is input to the computer so the computer knows what the car is rated to do.
high nox is caused by very high exhaust tempurates. you have done everything so-far that i would recommend. let me reasearch this. hang tight.