Emissions
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Elder User
Joined: Dec 2004
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From: Las Vegas
Well, I'm a little confused about my truck. It is a 78 that I bought in California (I don't know if thats where it orinigated from). It has the wide open fuel filler necks (Which means non catalist right?) However, it has a catalitic conveter; which is attached to a Flowmaster. I guess someone might have put the cat on later because they thought it was suppost to be there.
The reason I was wondering about the air pump is because I just failed emmisions. My truck does not have any emissions stuff on it (I don't know if it ever did). Then I wondered if having the pump would have made a significant differance. And why does everybody keep remoiving them?
The reason I was wondering about the air pump is because I just failed emmisions. My truck does not have any emissions stuff on it (I don't know if it ever did). Then I wondered if having the pump would have made a significant differance. And why does everybody keep remoiving them?
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Elder User
Joined: Dec 2004
Posts: 892
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From: Las Vegas
Originally Posted by Mike G
What part of the emission test did it fail?
--Mike
--Mike
Last edited by deisele75; Nov 3, 2005 at 09:39 PM.
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Logistics Pro
Joined: Jun 2004
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From: South Central Utah
High CO at an idle should be able to be adjusted lower to pass. The two air/mixture srews below the float bowl in front should be capale of adjusting the mixture lean enough to pass the CO cut point.
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From: Long Island USA
CO (carbon monoxide) is a by-product of an inefficient burn.
Too rich, or too lean, the CO goes up. Bad spark? CO goes up. Anything that makes the burn less-than-optimal makes the CO go up. Timing can effect it, too...
Too rich, of course, the HC's go up too. But lean it out too far, and while the HC's are low, the CO goes back up.
If it's an idle test, chances are the guy can put it in "test" mode and you can read off the CO on-the-fly. Adjust the idle mix until the CO is lowest. Good thing about this is it'll idle the best it ever did in it's life. I've done this and it's almost the ONLY way to get the thing to idle perfectly.
art k.
ps: Imagine a Triiumph TR7 (british 2.0L 4-cyl), with two two-barrel carbs, each barrel with it's own idle screw, and both carbs with their own idle-speed screws. Adjusted like I said above, and it idled and off-idled and ran the greatest it ever did... never could have done it by ear.
Too rich, or too lean, the CO goes up. Bad spark? CO goes up. Anything that makes the burn less-than-optimal makes the CO go up. Timing can effect it, too...
Too rich, of course, the HC's go up too. But lean it out too far, and while the HC's are low, the CO goes back up.
If it's an idle test, chances are the guy can put it in "test" mode and you can read off the CO on-the-fly. Adjust the idle mix until the CO is lowest. Good thing about this is it'll idle the best it ever did in it's life. I've done this and it's almost the ONLY way to get the thing to idle perfectly.
art k.
ps: Imagine a Triiumph TR7 (british 2.0L 4-cyl), with two two-barrel carbs, each barrel with it's own idle screw, and both carbs with their own idle-speed screws. Adjusted like I said above, and it idled and off-idled and ran the greatest it ever did... never could have done it by ear.
Logistics Pro
Joined: Jun 2004
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From: South Central Utah
CO is a rich/lean indicator. CO is "partially" burnt fuel due to a lack of oxygen for the amount of fuel present. Rich=high CO, lean=low CO. A misfire, whether it be caused by a mechanical condition like a burnt valve, an ignition misfire from a bad spark plug, spark plug wire or even "over" advanced timing increase HC, Hydrocarbon or unburnt fuel. An overly lean mixture can cause a misfire also which will increas HC.
If CO is high the mixture is rich, either too much fuel of not enough air, like a real dirty air filter.
If CO is high the mixture is rich, either too much fuel of not enough air, like a real dirty air filter.
Junior User
Joined: Feb 2003
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If in Calif. you'll likely have to have ALL the smog stuff on to pass. Even if the readings are OK, you aren't allowed to remove any smog stuff. If you or the PO ever used leaded gas, the cat is toast. Read the post about Smog Test failure... Mine passed with 0.00 CO just by leaning it out. (was over 5.0) All my smog junk is still there. 79 400M
Senior User
Joined: Aug 2005
Posts: 217
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From: Phoenix
ya in AZ you just register you vehicle to an other smaller town and keep your mailaing address your home one and you never get emmission tested cause its not required except in the large cities so they think your vehicle is someplace else when its where emissions it the strictest