Failed Hydrocarbon Emissions
Thread Starter
Instructor
Joined: Sep 2010
Posts: 166
Likes: 0
Failed Hydrocarbon Emissions
Hey guys, just took my newly aquired vette to emissions testing. Replaced the fuel injectors, egr valve, pvc valve, fuel filter, O2 sensor, plugs, and wires. I just missed my HC pass criteria. Fail limit is 2.0 and the vette blew a 3.0904. In their definition on the paper it says "high HC readings are a result of unburned or partially burned fuel." Any suggestions or tricks you could help with me with to get this thing to pass? I'm so CLOSE!!!! 
Racer
Joined: Jun 2010
Posts: 402
Likes: 1
From: Tabernacle NJ
Replace the Catalytic converters.
That's not "just missing", its 50% higher than the fail limit. Something is likely wrong with how the vehicle is running, but if all you're looking to do is pass emissions, replace the cats. Technology has made today's cat converters far better than before and with a new one, you're likely to pass even with some slight engine issues.
That's not "just missing", its 50% higher than the fail limit. Something is likely wrong with how the vehicle is running, but if all you're looking to do is pass emissions, replace the cats. Technology has made today's cat converters far better than before and with a new one, you're likely to pass even with some slight engine issues.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Is the service light on? You could have codes stored even without the light. If you do not have access to a code reader, you can use the search function on this forum to get how-to's on reading codes with a paper clip. If you find a code, that might point you in the right direction.
Thread Starter
Instructor
Joined: Sep 2010
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I'm thinking I may need to replace the Cap, rotor, and coil? Then get the engine timing right? No there has been no service engine lights on since I replaced the EGR valve. I havent checked to see if I have any hidden stored codes either. I will look into getting new cats though. There is 2 correct?
Thread Starter
Instructor
Joined: Sep 2010
Posts: 166
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CO=15.944 fail limit is 20.0
NOx=2.169 fail limit is 3.5
Car runs fine, doesnt chug like the cat is restrictive. Idles fine after you get it started, but does take a few revolutions to get it started. Have to crank on it for 2-5 seconds and pump the throttle a touch. Exhaust doesn't smell funky common with cats going bad.
NOx=2.169 fail limit is 3.5
Car runs fine, doesnt chug like the cat is restrictive. Idles fine after you get it started, but does take a few revolutions to get it started. Have to crank on it for 2-5 seconds and pump the throttle a touch. Exhaust doesn't smell funky common with cats going bad.
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Melting Slicks
Joined: May 2010
Posts: 2,082
Likes: 3
From: Conowingo Maryland
Your Co is also high even though you passed. Paul is right HC is a missfire be it from a simple plug miss to a weak cyl. A high HC can cause a high CO but almost never the other way around. With these reading the first thing I would check is the timing sence you have replaced the normal things that cause a misfire. was this an idle test or was it on a treadmill? I found the best way to locate HC problems is to put the car on a scope. This way you can see what is going on with each cyl at any time. Helps narrow it down.
