Just brought a 1992 3.1L V6 on 9/22/04. I did not pass the NYC Emissions test. So far this is what I have done to the car:
Replaced the air filter, plugs, wires and cap, oil change w/K&N oil filter using Castrol 10-40w, Flushed the raditor, changed the 02 sensor. Ran some Guarantee Pass stuff through my car (did nothing for it) just refilled with 94' Octane and added an engine treament it lowered the test slightly. So, I am now going to replace the Cat and have the ERG checked and see if the is a miss-fire going on this is what the readings where before the cat replacement:

Veh. Readings HC 7.18 gpm FAILED CO 13.47 Passed NOx 1.19
Test Limits: HC 0.80 gpm CO 15.00 NoX 2.00

This is crazy, my readings as of 5:30pm have changed, they did not put on the Cat, instead adjusted the timing, so now instead the HC has passed but now the CO is failing my readings are:

Veh. Readings HC 0.74 gpm PASS CO 15.35 Failed NOx 1.19
Test Limits: HC 0.80 gpm CO 15.00 NoX 2.00

I JUST PASSED :yes:

Thanks TomP for all your postings:rockon:

 

contact tomp, he lives in that area and just had to do some work to make his pass inspection.

 

Don't waste money on premium fuel with the V6. The 2.8/3.1/3.4 are all designed to run on 87 regular gas, and using high octaine will often hurt performance. Likewise, 10w 40 motor oil is too heavy for these engines, and robs power. Switch to a synthetic 5w 30 for better cold starting, smoother operation with the engine cold, and an increase in horsepower. Stay away from engine treatments. There's no such thing as a "miracle in a can".

 

Only miracle in a can seems to work is "Liquid Gumout".
Have used it on all my fuel injected rides since 1979. NOT often with newer style injectors, but, it's a help.
I agree with lower weight oil, but not synthetic.
HAVE HEARD synthetic in an higher milage engine "causes leaks" thru seals.
Yet any combo used to make a car pass smog, was right choice! I chose to use a 3.4 to make my Firebird pass!

Sounds like may need new plug wires, too.

 

Found this on the net. Its from Canada, but should help a little since we get so many "why didn't I pass" questions:

http://www.aircare.ca/index.php?repi...-causes-co.php

High CO is the first thing listed.