I have a stock -93 Camaro with 60'000 miles on it, and one month ago i failed the emissions test. I live in Sweden and they test CO at idle, CO at 2500 rpm, HC and LAMBDA. The car passed all tests, except CO 2500. These are the results:

(thresholds)/my car

CO Idle (0,5)/0,3
CO 2500 (0,3)/1,4
HC (100)/75
LAMBDA (0,96-1,25)/1,0

Later, i've noticed the a spark plug wire was not attached. So i attached the wire, went to the emissions test again yesterday, and this time, the CO 2500 was a lot better, but still failed, and the HC were way to high:

CO Idle (0,5)/0,2
CO 2500 (0,3)/0,6
HC (100)/158
LAMBDA (0,96-1,25)/0,99

I have access to a "scanner", which can't find any trouble codes. (except AC compressor) I've also captured 14 seconds of data while driving, but i don't know what to look at!

The car has passed the emissions for 4 years in a row before this, and nothing has been modified since then, except new spark plugs, oil, filter.

Its not a usual car in Sweden, so it's hard to find common model specific errors.

1. Is there anything specific to watch for, when capturing data from the "scanmaster"?
2. Does anyone know/have a theory on what's wrong with car?

 

You might try injector cleaner. The pro. stuff you run though the injectors not the stuff you put in the tank. There is also "Sea Foam" which cleans the intake and combuston chambers. Don't know if you have it there, but someone should know of a similar cleaner.

 

If it was just CO that was high I would say put a new cat on it but high CO and HC is telling me that it is runing rich. Either because of a faulty O2 sensor or an ignition problem...