roomylumy Posted October 19, 2007 Report Share Posted October 19, 2007 I changed spark plugs, wires, PCV valve and O2 sensor in preparation for my emission test, and just as standard maintenance. I drove the car for two weeks since and it was running like it was brand new, but as bad luck would have it, today the day of my emission test, it was running rough all day. Kind of stuttering during low rev driving. If I stepped on it, it went fine. It failed badly on HC and CO. It is a 1990 Lumina, 3.1L with 154 000 KM. Any idea where to start looking? Quote Link to comment Share on other sites More sharing options...
Euro Posted October 20, 2007 Report Share Posted October 20, 2007 How's your cat? I failed emissions in my Lumina cause of a bad cat. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted October 20, 2007 Report Share Posted October 20, 2007 Could you type out the full results of the test? HC & CO reading too high mean it's running rich. Do you have any other issues with the car such as hard starts, etc.? Quote Link to comment Share on other sites More sharing options...
1990lumina Posted October 20, 2007 Report Share Posted October 20, 2007 I changed spark plugs, wires, PCV valve and O2 sensor in preparation for my emission test, and just as standard maintenance. I drove the car for two weeks since and it was running like it was brand new, but as bad luck would have it, today the day of my emission test, it was running rough all day. Kind of stuttering during low rev driving. If I stepped on it, it went fine. It failed badly on HC and CO. It is a 1990 Lumina, 3.1L with 154 000 KM. Any idea where to start looking? My 90 Lumina runs the same way and we have similar mileage as well... I've pretty much ruled out everything but the fuel injectors. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted October 20, 2007 Report Share Posted October 20, 2007 what brand O2 sensor did you put in? Quote Link to comment Share on other sites More sharing options...
roomylumy Posted October 21, 2007 Author Report Share Posted October 21, 2007 No hard starts or anything like that. I don't recall the brand of the O2 sensor, but I bought it at a dealership, OEM replacement. Here ar the actual readings from the etest:(40 km/h): HC - 390ppm, CO - 1.39%, NO - 23ppm. (CURB IDLE): HC - 401ppm, CO - 1.04%. Quote Link to comment Share on other sites More sharing options...
GOT2B GM Posted October 21, 2007 Report Share Posted October 21, 2007 try installing a new cat. Quote Link to comment Share on other sites More sharing options...
Olds W31 Posted October 24, 2007 Report Share Posted October 24, 2007 I don't know if it is possible to alter the timing on our cars (old to cars, new to W bodies), but if you retarded the timing, it increases the heat in the exhaust and forces the cat to work harder. My 1993 'burb would not pass emissions here in Texas, til I retarded the timing so far it almost WOULD NOT run....tested cleaner than a new one! Quote Link to comment Share on other sites More sharing options...
roomylumy Posted October 24, 2007 Author Report Share Posted October 24, 2007 I found the problem. It was a bad spark plug wire. Didn't expect that with them being new and all, but at least I got it. Thanks for your time. Quote Link to comment Share on other sites More sharing options...
GutlessSupreme Posted October 24, 2007 Report Share Posted October 24, 2007 I don't know if it is possible to alter the timing on our cars (old to cars, new to W bodies), but if you retarded the timing, it increases the heat in the exhaust and forces the cat to work harder. My 1993 'burb would not pass emissions here in Texas, til I retarded the timing so far it almost WOULD NOT run....tested cleaner than a new one! It's not, these cars don't have distributors/rotors. You'd have to do chip mods. Quote Link to comment Share on other sites More sharing options...
Olds W31 Posted October 25, 2007 Report Share Posted October 25, 2007 Gotta search for options regarding chip changes. My 3100 NEEDS more umph! Quote Link to comment Share on other sites More sharing options...
Euro Posted October 25, 2007 Report Share Posted October 25, 2007 Gotta search for options regarding chip changes. My 3100 NEEDS more umph! Contact Ben at http://www.60degreev6.com. He does chips for the 3100 that actually help. The others like the Hypertech or whatever don't do anything. Quote Link to comment Share on other sites More sharing options...
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