Chevy lumina 1993 3.8 fail emission due to high hc co mean?

Answer 1

This means that there is too much unburned gasoline coming out of the tailpipe. Possible causes:

1-Low temperature. Check your engine coolant temperature. It should be between 195 degrees and 220 degrees. If it is below 195, replace the thermostat.

2-Misfire. Does the car vibrate when accelerating? If so, do a misfire diagnosis, then repair the problem.

3-Overly rich fuel mixture. If your check-engine/SES light comes on, start there. Otherwise, check for any exhaust system leaks that can fool the oxygen sensor.

4-Damaged or cold catalytic converter. To be sure the converter is fully warmed up before the emissions test, drive the car for at least ten minutes. While waiting for the test do not shut the car off. Immediately before testing, use the accelerator pedal to hold engine speed at about 2000 RPM for 30 seconds to a minute. If you can hit the catalytic converter (when cold) with your hand and it makes a clunk noise, replace the converter and all pipes from it to the tailpipe, and the muffler as well. Beyond that, testing of the catalytic converter requires a gas analyzer which is a very expensive tool.

5-Malfunctioning AIR system, if equipped. This doesn't happen much, so I won't go into detail on it. It's only likely to affect emissions testing if the test is an idle test or 2500RPM test. This will not affect a dynamometer test.