OnBoard Diagnostics: Also known as OBD. Mandatory since 1981 on U.S. cars. There are two kinds of OBD systems. OBD1 is for cars made from 1981 to 1995. OBD2 is for 1996 and newer vehicles. Since the first one falls within the smog-era, that’s what we’re covering here, through ’83. General speaking, OBD is a […]
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Evaporative Emission Control: Also known as the EVAP system. Common starting in 1972. Gasoline is always evaporating! The idea behind this system is to catch some of those vapors when they escape from your fuel tank. Early systems such as those found in smog-era cars catch only part of the evaporating fuel, but later systems […]
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Air Injection Reaction: Also known as A.I.R. or ‘Air Injection Reactor’. Became common in 1974, but not all manufacturers utilized an A.I.R. system. The A.I.R. system is probably the number one ugly thing that was done to engines of the smog-era. The core of the system is really not that ugly and is usually tucked […]
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Exhaust Gas Recirculation (EGR): Exhaust Gas Recirculation System. Became common by 1973. On an EGR engine, there are extra exhaust ports inside the cylinder heads that exhaust gases flow back into the air/fuel intake stream. The flow of these gases is controlled with a vacuum actuated piece called an EGR valve. It completes a connection […]
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Catalytic Converter: Debuted in 1975. These devices get red hot on the inside and essentially burn the carbon monoxide and hydrocarbons left over from the engine’s combustion process. They are also known simply as a ‘catalyst’. ‘Pelletized’ was the early style of catalyst. Exhaust gases flow through thousands of pellets which are coated with platinum […]
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Positive Crankcase Ventilation (PCV): Also known as a PCV valve. These became common around 1967. Simply put, it’s a one-way valve that keeps engine ‘blow-by’ gases from entering the outside air. All engines, no matter how new or how efficient they are, allow some unburnt gases past the piston rings and into the oil pan. […]
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