Air System Operation

Air Pump:

The AIR system is used to reduce Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides Of Nitrogen (NOx), and exhaust emissions during engine start-up when the catalytic converter is not yet hot. By heating up the catalytic converter quickly on engine start-up, the conversion of exhaust emissions to Carbon Dioxide (CO2) and water can occur sooner. The AIR system consists of the following components:
1. Air Pump
2. Air Pump Solenoid
3. Shutoff Valve
4. Check Valve (keeps exhaust gas from entering the air pump)
5. Check Valve (keeps vacuum in the solenoid vacuum line)
6. Air Pipe and Hose
7. Air Pump Relay - located in the Underhood Fuse Block (UHFB).
8. Powertrain Control Module (PCM) - located underhood on the right side front of dash.

The air pump is a permanently lubricated turbine type pump which requires no periodic maintenance. The PCM runs the air pump for a certain length of time when the engine is started within a certain ECT range. When the AIR system is commanded On, the PCM will turn on two internal drivers which pulls the air pump relay coil circuit and air pump solenoid to ground allowing current to flow to the air pump and air pump solenoid simultaneously.

The air pump solenoid is used to control vacuum to the shutoff valve. A check valve is used inline between the manifold vacuum supply and air pump solenoid. The check valve is used to maintain vacuum for a certain amount of time to the solenoid when manifold vacuum decreases. When the PCM commands the air pump solenoid On, the air pump solenoid will energize (internal valve opens) and will allow manifold vacuum to pull up on the shutoff valve diaphragm.

NOTE: The air pump solenoid contains a calibrated vacuum leak and is not designed to hold vacuum for any notable length of time.

When the shutoff valve diaphragm moves up, pressurized air from the air pump flows past the inline check valve to the exhaust manifold. The one-way check valve is used to keep exhaust gas from entering the air pump.