I have a '95 Civic EX with 187K miles that runs great. Last oil change was 2,500 miles ago. I went to motor vehicles less than 10 miles away on a cold engine with a full tank of gas. My emissions were incredibly high.

Mode: IDLE

HC ppm: 725 (standard 220), CO%: 5.42 (standard 1.20), CO2% 11.4, O2%: 1.2

Mode: HIGH IDLE

HC ppm: 547 (standard 220), CO%: 9.82 (standard 1.20), CO2%: 8.2, O2%: 0.5

I searched in net, but didn't find comparable results to mine. Before heading off to a "registered emissions repair facility", what steps can I take on my own? Any help is appreciated. Thanks.

 

Does the engine warm up to normal temperature-- gauge halfway up?

Was NOx unusually low? (Do they measure NOx there?)

 

The engine does warm up to a normal temperature.

NOx isn't measured in NJ.

 

High HC and CO usually means the engine is running with too much fuel. Take all the spark plugs out and see if they are the same color-- if one is black it could be a bad fuel injector on that cylinder. Check that the small vacuum line on the fuel pressure regulator is hooked up. This is of course assuming the car is stock, and there is no CEL on or codes stored in the ECU. If you saw high NOx as well it could be that the cat converter is worn out, but since NOx wasn't measured you can't tell.