DESCRIPTION
The air injection system is used to add secondary air to exhaust ports for further burning of hot exhaust gases. System consists of an air pump with a built-in relief valve, a check valve, an air injection manifold with air injection nozzles, an air switching valve, and a mixture control valve.
The mixture control valve prevents backfiring in the exhaust system during deceleration. The air system is controlled by the electronic control module of the I-TEC system.
AIR PUMP
Air pump draws fresh air in, pressurizes it and passes it along to the rest of the system. A built-in relief valve will bleed off any excess pressure occurring in the air pump. Normal pump pressure is 2.8-5.0 psi (0.2-0.4 kg/cm 2 ).
CHECK VALVE
This one-way valve is designed to allow air to flow into the air injection manifold. When exhaust system pressure is greater than air pump pressure, check valve closes to prevent exhaust gas from flowing back into air pump system and damaging components.
VACUUM SWITCHING VALVE
The vacuum switching valve has 2 ports. The application of manifold vacuum to the air switching valve is controlled by the electronic control module.
Air Switching Valves (Typical) Normal operating position shown. Scheme 5
The ASV is operated by air pump pressure and by intake manifold vacuum through the vacuum switching valve. The ASV redirects air flow from the air pump to either the check valve or to the atmosphere.
When manifold vacuum is applied to pipe 1, the ASV allows air to flow from air pump to the check valve. When the vacuum switching valve directs air pump pressure to pipe 1, the ASV shuts air flow to air injection manifold, and at the same time vents pressure to the atmosphere (air cleaner).
MIXTURE CONTROL VALVE
This normally closed valve prevents backfiring in the exhaust system on deceleration. The mixture control valve allows atmospheric air to enter the intake manifold during deceleration.
When high intake manifold vacuum is sensed, valve opens and atmospheric air is directed into intake manifold to combine with rich mixture caused by rapid closing of throttle valves.
Mixture Control Valve (Typical) Valve adds air to intake manifold during deceleration. Scheme 6
Apply 12 volts to air pump assembly. Check that air pump motor turns and that air flows freely from intake side to output side of pump.
AIR SWITCHING VALVE
Apply a vacuum of 3.9 in. Hg to diaphragm of air switching valve. Check that air flows freely from air pump side of valve to air check side of valve.
Remove check valve from air manifold. Blow air into valve from both sides. Air should only pass through from air pump side of valve. If air passes through from manifold side of valve, replace valve. A small amount of leakage is normal.
- With engine running, disconnect rubber hose between mixture control valve and intake manifold. Plug intake manifold connection.
- If valve is operating normally, air will flow through valve for a few seconds after accelerator pedal is depressed to floor and quickly released. If air continues to flow after 5 seconds, replace mixture control valve.
Apply 12 volts to vacuum switching valve. Check that air flows freely through valve. Remove voltage and check that air does not flow through valve. Replace valve, if necessary.