Smog equipment basics
Drifting
Joined: May 2001
Posts: 1,630
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From: Brandywine, Chester and Ridley Valleys Pennsylvania
Re: Smog equipment basics (aobrien)
I guess our good friend the cat would qualify as smog equipment. So would the canister which holds gas fumes (I forget the name of the system, Evap/Purge?). So would a gas cap, I guess! :D Heck, properly functioning spark plugs could qualify too, after all the recommended gap is on the VECI label...
Smog or AIR pump sends air to the exhaust when cold, this helps warm the cat up. The air pump also sends air past the cat to aid in completing the combustion of anything that got out of the cylinders "unburnt".
The EGR system, under certain situations, takes exhaust gases and blends them in with air in the intake manifold to help clean up emissions.
PCV is sorta the same thing, just that it is really there to vent the crankcase (duh), sending the blowby back into the intake (via the throttle body on my cars). I guess in days gone by, the blow-by was vented right out the valve covers into the atmosphere. Can't do that anymore with a factory car.
Smog or AIR pump sends air to the exhaust when cold, this helps warm the cat up. The air pump also sends air past the cat to aid in completing the combustion of anything that got out of the cylinders "unburnt".
The EGR system, under certain situations, takes exhaust gases and blends them in with air in the intake manifold to help clean up emissions.
PCV is sorta the same thing, just that it is really there to vent the crankcase (duh), sending the blowby back into the intake (via the throttle body on my cars). I guess in days gone by, the blow-by was vented right out the valve covers into the atmosphere. Can't do that anymore with a factory car.
Thread Starter
Tech Contributor
Joined: Aug 2001
Posts: 472
Likes: 39
Re: Smog equipment basics (TrueBlue ChevyDude)
The air pump is more complicated than I had imagined. I was also thinking the the PCV valve and the EGR valve were different names for the same thing.
Thanks for settimg me straight TrueBlue :)
Thanks for settimg me straight TrueBlue :)
Drifting
Joined: Sep 1999
Posts: 1,411
Likes: 1
From: Wylie TX
Re: Smog equipment basics (TrueBlue ChevyDude)
Smog or AIR pump sends air to the exhaust when cold, this helps warm the cat up. The air pump also sends air past the cat to aid in completing the combustion of anything that got out of the cylinders "unburnt".
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Smog equipment basics (Chris A)
A certain amount of unburned gasoline leaves the combustion chamber. You see these as HC (hydra carbons) on your smog check sheet. By introducing fresh air into the hot exhaust gases, the HC can continue to burn in the exhaust system. The more that burns there, the less that leaves the tailpipe. With a computer controlled car, the heat of the HC oxidizing in the head pipe lights off the O2 sensor. Once the O2 sensor is "on line" the ECM sends the fresh air to the cat where it can help oxidize the polutents is the presents of the catalysts in the converter. Before the days of the converter, the fresh air just did it's thing in the exhaust pipe. Clear as mud?
