Free ASE PREP – AIR INJECTION
Another segment from my ASE / BAR Smog License Course, which runs once a year in January.
A defective Air Injection System can cause you to fail an emissions test and cause a drivability problem?
A.I.S. has two valves install on the system they are usually located in the air line between the pump and the exhaust manifold. One is a diverter valve, the other a one way check valve.
The diverter valve job is to do what it sounds like, it diverts, and basically it redirects air from the air pump away from the exhaust on deceleration so the vehicle will not backfire when the customer releases the gas pedal.
Also at normal operation it helps direct the air from the air pump to the air pump rail to help reduce Carbon Monoxide, “CO” and Hydrocarbons, “HC”.
Now the check valve job is to prevent the exhaust gases from coming back into the engine compartment while the Air Pump adds additional air into the exhaust to help lower emissions.
Remember the A.I.S. reduces Carbon Monoxide, “CO” and Hydrocarbons, “HC”.
If you ever see the under hood engine components burnt up, especially around the Air pump area suspect a defective check valve.
The check valve is letting the hot exhaust back into the engine compartment and the heat from the exhaust is burning the components.
What is the purpose of the A.I.S.?
This left over fuel is a major source of HC and CO emissions. If combustion could be maintained until all fuel is burned, HC and CO levels would be significantly reduced.
Heat in the exhaust system is sufficient to ignite an air/fuel mixture.
Unburned fuel is present in the exhaust manifold the A.I.S. or Air Injection system job is to help lower the remaining emissions in the exhaust.
The end result will be lower Hydrocarbons and Carbon Monoxide from the tail pipe.
So to sum this up the Air Injection System,”A.I.S” emission system was developed to provide extra oxygen in the exhaust system to complete the burning process?