Failed smog. High %o2 at 15mph?

[e30serg]

So, my car has been sitting for about 1.5 years and I finally took it in for the ol' smog test. Well, it failed the 15mph test. I changed the following before the test:

-Intake manifold gaskets
-Throttle body gasket
-Water pump
-Timing belt
-Thermostat
-Re-built injectors (Witchhunter)
-New O-rings on oil drain tube below intake manifold
-All cooling system hoses
-Radiator
-Valve cover gasket
-Front crank and cam seals (I know it doesn't matter for smog)
-Air filter
-Spark plugs
-Oil and filter

I didn't replace the cap and rotor, or plug wires. Also didn't replace the o2 sensor. The cat is 3 years old or so (I think). Also had half a tank of old gas and half of new gas.

Here's the result:


The thing that stood out to me was the high %o2 level at the 15mph test. What does this mean? Is my o2 sensor dead?

[Cabriolet]

im thinking you you need an O2 very bad and and have an intake leak. do you have a mildly rough idle?

[bddog]

Change your oil. Fix all intake leaks. New o2 sensor. Only new gas in half tank- add some additive for passing smog test. Drive at high speed for twenty minutes( freeway). Pull into uncrowded smog station. Make sure your cat is hot. Do not turn it off.- works for me

[rhE-30]

I kinda of got similar results, what did you do to pass? Or what can I do? The smog tech, kinda thought it was an issue with the fuel system. I'm currently changing the fuel filter but i doubt that is the problem.

[e30serg]

My idle is more or less ok. I'll try a new o2 sensor I forgot to add that I drove the car for about 1 hour through traffic in the city and highway. Also, my car was idleing while waiting at the smog station.

rhE-30-our results are similar but my %o2 at mph is way high. Not sure why....
Did you fix yours?

[rhE-30]

Nah, haven't fixed it yet, I have replaced the fuel filter and put injector cleaner in the gas tank(doubt it works tho). It still smells bad on acceleration, just like the smog tech pointed out when he was testing it, even though I'm on the second gas fill after the additive. I think it may be a leaky injectors, but that's my e30 mechanical novice theory. I'm gonna remove and clean the injectors and replace the cat before taking it back to smog.

and just to note I had a one month old O2 sensor.

edit: another suspect, is the platinum plugs that are in there now, I have seen post that copper is the only way to go.

[BMWamongJDM]

Change the cat end of story mine failed hc bad 5yo cat got a new one ran 91 and passed. It barely was on the charts

[jlevie]

High HC & High NOx are most commonly from a bad catalytic converter, but partial misfires from bad ignition wires/plugs and or an aged O2 sensor can contribute to the problem.