calling all tuning gurus, failed emissions
Thread Starter
Pro
Joined: Jun 2000
Posts: 569
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From: phoenix az
calling all tuning gurus, failed emissions
help. I passed all but one catagory. Loaded HC and CO2 were good, Idle HC was good. Failed idle CO. was allowed 200ppm and I had 293ppm. what do I do? I go through this every year. fail, take it and have it adjusted, passes. Is ther anything I can do myself short of taking it in to reduce CO? Any help would be appreciated.
Le Mans Master
Joined: Nov 1999
Posts: 5,768
Likes: 3
From: San Diego CA
Re: calling all tuning gurus, failed emissions (BubbaJJ)
Carbon monoxide (CO) is a product of incomplete combustion and occurs when carbon in the fuel is partially oxidized rather than fully oxidized to carbon dioxide .
As to solutions...wish I could help
As to solutions...wish I could help
Melting Slicks
Joined: Nov 2000
Posts: 2,663
Likes: 3
From: Palm Harbor FL
Re: calling all tuning gurus, failed emissions (BubbaJJ)
Would leaning out your idle mixture help?
I had to do this on an old car of mine and it passed. Just don't forget to set it back after the test. Caused MAJOR problems for me, but that's a long story.
[Modified by 79MakoL82, 10:06 AM 8/9/2001]
I had to do this on an old car of mine and it passed. Just don't forget to set it back after the test. Caused MAJOR problems for me, but that's a long story.
[Modified by 79MakoL82, 10:06 AM 8/9/2001]
Melting Slicks
Joined: Jan 2000
Posts: 2,386
Likes: 3
From: far, far away
Re: calling all tuning gurus, failed emissions (BubbaJJ)
I'd try setting the timing back a bit. That has made the difference for me on other vehicles. Obviously, if the car's not running clean at idle, you'd look at idle mixture, float levels, dirty oil, bad PCV valve, or anything else that would tend to dirty it up at idle. Most of those, tho, should show up as excessive HC levels, rather that CO, so you're probably pretty close. Retarding the timing will heat up the exhaust, I'd bet enough to make the difference. You don't need much. If it's set at, say, 10 degrees BTDC at idle now, setting it back to 6 is probably enough to do it. It's easy enought to adjust. Be aware that your engine torque will drop off, so the car won't feel nearly as powerful as it usually does, until you set the timing back where it should be.
Burning Brakes
Joined: Feb 2001
Posts: 866
Likes: 1
From: Peabody,MA,USA
Re: calling all tuning gurus, failed emissions (BubbaJJ)
Retarding the timing is the way to pass. Do not be afraid to excessivly retard the timing. The engine will have no power but should pass the test. When you retard the timing allot the exhaust will have enough unburnt fuel and O2 to keep on burning as it travels down the exhaust pipe.
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Re: calling all tuning gurus, failed emissions (BubbaJJ)
You're running too rich at idle. Try leaning it out with your idle mixture adjustment screws. If that doesn't work you may have to take a closer look at a carb rebuild, especially your idle mixture circuit. Retarding your timing won't do anything for CO. CO responds to air fuel ratio not spark advance. CO is the product of combustion with an insufficient amount of oxygen (too much fuel).
Retarding timing will work to reduce HC and NOX, though.
Good Luck!!
Retarding timing will work to reduce HC and NOX, though.
Good Luck!!
Thread Starter
Pro
Joined: Jun 2000
Posts: 569
Likes: 0
From: phoenix az
Re: calling all tuning gurus, failed emissions (BubbaJJ)
well, I made it through!!! :D what I did was retard the timeing way down from where it was. I had it set at about 14 BTDC from when I went to the track. Never bothered to set it back down cause it seemed to run better that way. I set it back to 8 and I left the advance unplugged. CO went from 2.93% (its measured in %, not ppm, OOPS) to 1.99, just under the 2.00 standard. WOOHOOO!! now I get to drive it for at least one more year. Thanks everyone for your help.
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