High CO's on emmisions test
Thread Starter
Melting Slicks
Joined: Oct 2002
Posts: 2,106
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High CO's on emmisions test
What can i do to bring them down? I rebuilt my carb and my HC's dropped more than 11 fold but i am still having trouble passing my CO's. I ran the car through the emmisions facility and i failed my CO's on the driving test, i got 1.5% and maximum was 1.32%. I also failed the CO's on the idle test. i got 4.07% and maximum was 3.91%
So my driving test was off by .18%and my idle was off by .16%.
A mechanic at work had told me that high CO's can be caused by high underhood temperatures which boil the gas in the carb and therfore make the car run richer. I then let the car cool down for 30mins with the hood open on that windy day and went through again(this time i didnt let the car run while in the lineup). I passed on the driving this time with .72% and also my HC in the driving went down by 20ppm(to 63ppm). However i failed on the idle test again, i got 4.29% of CO's where i was only allowed 3.91%, the hydrocarbons also went up on this test from 159ppm to 222ppm.
In summary the car failed by .18 ondriving and by .16 on idle and after a 30min cooldown it passed driving and failed idle by.38.
what should i do? I was thinking maybe a carb spacer, i already have a MR. gasket style spacer.
thanks in advance, sonny
So my driving test was off by .18%and my idle was off by .16%.
A mechanic at work had told me that high CO's can be caused by high underhood temperatures which boil the gas in the carb and therfore make the car run richer. I then let the car cool down for 30mins with the hood open on that windy day and went through again(this time i didnt let the car run while in the lineup). I passed on the driving this time with .72% and also my HC in the driving went down by 20ppm(to 63ppm). However i failed on the idle test again, i got 4.29% of CO's where i was only allowed 3.91%, the hydrocarbons also went up on this test from 159ppm to 222ppm.
In summary the car failed by .18 ondriving and by .16 on idle and after a 30min cooldown it passed driving and failed idle by.38.
what should i do? I was thinking maybe a carb spacer, i already have a MR. gasket style spacer.
thanks in advance, sonny
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: High CO's on emmisions test (battsup)
Turn your idle mixture screws in until you get a 50rpm drop in idle speed. Then, crank your idle speed up to the upper limit of the acceptable idle speed for your test (check to see what the allowable idle spec is - run the rpm up to within 50rpm of the idle speed limit).
Thread Starter
Melting Slicks
Joined: Oct 2002
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Re: High CO's on emmisions test (lars)
Lars i forgot to mention that i took it to a mechanic at the dealership i work at right before i went to the test place and he had it up on the machine. He turned down the CO's as much as he could by leaning out the mixture.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Re: High CO's on emmisions test (battsup)
Just turn it a little leaner still. Your idle will be rough that lean, but it will pass the test and you can richen it up once you got the sticker.
The Carter AFB was not intended to be an emissions complient carb so you will always have rather high emissions with it.
The Carter AFB was not intended to be an emissions complient carb so you will always have rather high emissions with it.
Thread Starter
Melting Slicks
Joined: Oct 2002
Posts: 2,106
Likes: 0
Re: High CO's on emmisions test (zwede)
alrite guys now i gotta get my tach working, so are you guys saying i shouldn't put the spacer in? The mechanic at work said that since i am only off by so little that it may do the trick. Also should i get it really hot before i get there?
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Re: High CO's on emmisions test (battsup)
No, I don't see you needing a spacer. Getting it hot is good. Run it down the freeway for 20 minutes or so just before the test. Remember, turn the idle mixture screws in so that it runs a little rough. Turn the idle speed up just under the max they allow (probably 1000 rpm).
