its a 1995 Lexus SC300.

Here were the results it posted.

Hydrocarbons (HC) Grams/mile 0.33 of 0.80 allowed
Carbon Monoxide (CO) Grams/mile 0.67 of 12.00 allowed
Oxides of Nitrogen NOX in grams/mile 5.85 of 2.00 allowed

Things I did prior to the test.

I reinstalled EGR valve.

Its stock with exception of BFI intake, Lower TOM temperature thermostat. Tune up was done about 12 months ago with TM spark plugs.

they drove the car and they did it with Overdrive off and it hit speeds of up to 55-60 mph. So rpms were above 3000 rpms during this test.

So far my only idea to reduce NOx is to reinstall stock thermostat, and go over my egr install. Although there is no hesistations while driving at all. And all the egr components. And maybe tape the OD button off so that OD stays engaged!!!!

Anything else I could be missing?

So no one else has any idea what else I could do to richen this car out slightly more?

on my cressida, my nox was too much, so i got a new cat and i changed the o2 sensors and passed w/ flying colors.

cant u add some fuel aditive in the gas tank to pass?

Fuel additive don’t do jack (i ran 3 bottles n still faild), get a new cat all pass w/o a problem. I tried just about every thing the only thing that worked was a new catt.

how about a SAFC 2 - add more power and run it rich when ever u need to

btw im only half kidding cuz one part of me is saying it should work.. and the other is like... maybe not cuz it seems too simple.. to me its a bit of a win win situation

Similiar reading of NOx on my SC when she failed inspection. I needed O2 sensors. Are you throwing a CEL?

doubt it's the cat...

we do smog repair at our shop, and have only once recommended the cat be replaced...

other things to look for - EGR lines blocked / passages closed, car not getting to proper operating temperature (a low temp thermostat is not usually a good thing, not even for performance), o2 sensor out of range (working, but not right), incomplete combustion (bad plugs / wires / dist cap / rotor), and more...

if we get more info, I can probably help more, but you are going to need to do some diag work here... might need a code reader (not to read codes, but to watch different systems for erratic readings)...

No sirreee!

Im going to check the timing see if its a little to advanced or not. I put the stock thermo back in there. Rechecked my EGR lines (everything is in the same condition as it was when purchased 2 years ago, since they were not used.) There is absolutely no hesistation, and the egr items are brand new, so I doubt its that.

Ill retard the timing a bit see if that helps?

And I have a SAFC 2 for it, but ... It doesnt work when its inside the glove box. (Ill put it on after emmissions.)

If all this fails, Ill replace 02 sensor, and try again.

It seems to me though that Im running on the lean side, by looking at those numbers. Very low HC and CO but high NOX.

I had high nox once and it was the cat.

Thermostat is cheap and follow up on the EGR install and O2 sensors. Those would be my first steps. I would then look at a possible cat. Any codes?

5 hours after this message. I love how this things take 48-72 hours to appear.

The dreaded code 71 reapeared once again, pinpointing on the EGR. I had replaced every EGR component, except one the VSV valve.

Followed some testing procedures according to Alldata, and for now it appears to be the culprit. Replacing this, and checking my timing will be my next course of action.

have you checked that the EGR lines actually flow?

many many times we get customers replacing working equipment such as EGR valves, only to find out it wasn't faulty, and that it was a blocked passage or a loose vacuum line which cost pennies to fix in comparison...

I still believe the EGR system is not functioning property or it may be an O2 sensor.

However I PASSED!!!!

New results

HC 0.08 out of .8
CO 0.42 out of 12.00
NOX 1.98 out of 2

I barely passed it.

This is what I did. I replaced the VSV valve. Replaced thermostats.
I took it to retest it and failed although it did half the nox readings.

I retarded the timing again, till where the car is still drivable. Which turns out to be its somewhere around -3 degrees before top dead center. Anything less then this and the car runs like poo.

It runs extremely sluggish.

I had it originally around 15-18 degrees btc. Im probably going to reset it to 12-15 degrees btc.

Where I had it before, it was extremely responsive on the throttle so Ill reset it to that.

Crazy to believe that the sr20det has lower nox readings without a need to have an EGR system. However it posted much higher HC and CO readings. it still passed with flying colors though.

Did you try Toulene?